. 14.0 . n... E4... tin-9.2.6: N. F} Iliazkfic nnvh’l .11.? 3:1 I: a . run-2:11. .3: , ‘iiunlsuuuw. i.) mm u .m guns... $43.. 3 =21 Nam .. .Ifi n..l.~..x2.... ggmmuounwr mm W . _ 1.1.853; 311’)! .15. {ti-.IEZ-i‘. . . 50:15:22. (.1). I .ollfil‘II. Ilse-Pi‘I-lhl‘lr m. m m . , I u M'Fgmfi‘ . 13!? x} .5! taifiv 71:); (3):... 305.....1'}: 15.1.5.1)?! gar. o-mxmtvmwva.vymn my: THESIS 2607/ This is to certify that the dissertation entitled THE TOTAL SYNTHESIS OF THE ASSIGNED STRUCTURE OF AMPHIDINOLIDE A presented by Lamont R. Terrell has been accepted towards fulfillment of the requirements for Ph.D. degree in Cheml Stry W W (\A/ Major professor \) Date August 17, 2001 MS U is an Affirmative Action/Equal Opportunity Institution 0- 12771 LIBRARY Michigan State Unlverslty PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before date due. MAY BE RECALLED with earlier due date if requested. DATE DUE DATE DUE DATE DUE 6/01 c:/CIRCIDateDue.p65~p.15 THE TOTAL SYNTHESIS OF THE ASSIGNED STRUCTURE OF AMPHIDINOLIDE A BY Lamont R. Terrell A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Chemistry 2001 ABSTRACT THE TOTAL SYNTHESIS OF THE ASSIGNED STRUCTURE OF AMPHIDINOLIDE A BY Lamont R. Terrell We initiated a synthetic venture aimed at the construction of the anti- leukemic macrocycle amphidinolide A (1). A synthetic target of considerable interest, amphidinolide A has marked biological activity and several striking structural features, including the contrast of lipophilic and hydrophilic moieties as well as the presence of both conjugated and non-conjugated dienes. Issues guiding our retrosynthetic plan, included the formation of multiple stereocenters early in the synthesis, the development and evaluation of new synthetic methods, and maintaining a flexible approach to the target molecule. Indeed, the successful construction of the subunits in our first generation retro-analysis allowed for the investigation of multiple coupling strategies and provided valuable information as to which coupling sequence was employed in our final approach to the total synthesis of amphidinolide A. ACKNOWLEDGMENTS I would like to express my deep appreciation to Professor Robert E. Maleczka, Jr. for his guidance and encouragement throughout the course of my Ph.D. studies. I could not have asked for a better advisor. I would also like to thank Professors Greg Baker, Babak Bohran, Paul Mantica and Paul McCracken for serving on my guidance committee. I wish to thank Professors William Reusch, Mike Rathke and Peter Wagner for the helpful discussions throughout my Ph.D. studies. I am very grateful to the NMR staff, Le Long Dinh and Kermit Johnson, for without their support my work would be impossible. On a personal note, I must thank my parents, Thelma and Larry, for encouraging me throughout my life. Without your support, all of my achievements and successes would not have been possible. This one is for you. Upon my arrival at MSU, I only had one family but upon my departure l have been blessed with a lovely wife, Susan, and son,Tyrus. You both are the love of my life. I will be forever grateful for you’ll acceptance and understanding of the long hours that I spent in the lab. I will make it up. Thanks to all my colleagues in Professor Maleczka's group for their friendship and help, especially Joseph Ward and Feng Geng, who have worked so hard to finish the total synthesis of amphidinolide A. I would like to thank all my basketball buddies from Tuesday mornings and Friday afternoons. It was fun. If you’ll practice a little harder, maybe one day you will win. TABLE OF CONTENTS LIST OF TABLES vi LIST OF FIGURES vii LIST OF SCHEMES viii LIST OF ABBREVIATIONS xiii INTRODUCTION AND PRIOR WORK 1 CHAPTER 1 IST GENERATION APPROACH - SYNTHESIS OF FRAGMENTS 6 Synthesis of Fragment A 7 D-glyceraldehyde Acetonide Approach 7 Triol Approach 8 Payne Rearrangement Approach 9 Improved Synthesis 16 Synthesis of Fragment B 18 Synthesis of Fragment C 21 Synthesis of Fragment D 22 CHAPTER 2 COUPLING AND ELABORATION OF 1ST GENERATION SUBUNITS 24 Coupling of Fragments A and B 24 Hydrostannylation of Skipped Enyne and Subsequent Cross-Coupling 31 Hydrolysis of Advanced lnterrnediates 39 CHAPTER 3 2ND GENERATION APPROACH - APPLICATION OF ROM 47 Total Synthesis of “Z-amphidinolide A 48 Total Synthesis of the Assigned Structure of Amphidinolide A 63 Total Synthesis of an Epimer of Amphidinolide A via L-arabitol 69 CHAPTER 4 39° GENERATION APPROACH - APPLICATION OF ALDER-ENE RXN 73 CHAPTER 5 INDIUM MEDIATED REACTIONS 78 Investigation of an Indium Mediated Macrocyclization 78 Generation of Vinyl Indanes and Subsequent Addition 82 CHAPTER 6 IN SITU FORMED BU3$nH AND SUBSEQUENT HYDROSTANNYLATION 86 CONCLUSIONS 94 EXPERIMENTAL SECTION 95 Materials and Methods 95 REFERENCES AND NOTES 240 LIST OF TABLES TABLE 1. Cytotoxicity Data of Various Amphidinolides vi FIGURE 1. FIGURE 2. FIGURE 3. FIGURE 4. FIGURE 5. FIGURE 6. FIGURE 7. LIST OF FIGURES Retrosynthetic Analysis of Amphidinolide A Felkin-Ahn Model Diene ABCD Acetal Hydrolysis By-products Semi-symmetrical Intermediate Hoveyda’s Catalyst Possible Structure of Amphidinolide A or its enantiomer vii 24 38 42 45 66 68 SCHEME1. SCHEME2. SCHEMES. SCHEME4. SCHEME5. SCHEME6. SCHEME7. SCHEME8. SCHEMEQ. SCHEME 10. SCHEME 11. SCHEME 12. SCHEME 13. SCHEME 14. SCHEME 15. SCHEME 16. SCHEME 17. SCHEME 18. SCHEME 19. SCHEME 20. SCHEME 21. SCHEME 22. LIST OF SCHEMES Several Amphidinolides Williard’s Approach Pattenden’s Model Study Pattenden’s Retro-analysis Amphidinolide A Retrosynthetic Analysis Synthesis of 1,2-epoxy—3-ol (11) Synthesis of 2,3-epoxy-1-ol (14) Attempted Moffatt Epoxidation Model Payne Rearrangement Non-aqueous Payne Rearrangement lntramolecular Sulfide Displacement Investigation Synthesis of 2,3-epoxy-1-ol (21) Payne Rearrangement and In Situ Opening Isolation of 1,2-epoxy-3-ol (23) Optimization of the Oxidation and Wittig Olefination Preparation of a-acetoxy sulfide 27 Isolation of Fragment A Streamline of Fragment A Synthesis Super-Hydride" Workup Attempts Toward Known Diyne 39 Unsuccessful TMS-acetylide Displacement Phase Transfer Conditions Toward Subunit B viii 10 11 12 12 13 14 15 16 17 17 18 19 19 SCHEME23 SCHEME24. SCHEME25 SCHEME26 SCHEMEZZ SCHEME28 SCHEMEZQ SCHEME3Q SCHEMESL SCHEME32 SCHEME33 SCHEME34 SCHEME35 SCHEME36 SCHEME31 SCHEME38 SCHEMESQ SCHEME4Q SCHEME4L SCHEME42 SCHEME43 SCHEME44 SCHEME45. Synthesis of Fragment B Synthetic Approach to Fragment C Synthesis of Fragment D (I) lsomerization of Acids Attempted Grignard Formation Coupling of Fragment B and Valeraldehyde Mechanism of By-product Formation Coupling of Fragment B and Aldehyde 33 (A) Synthesis of the PMB Derivative of Fragment A Diastereoselective Coupling of Fragment B and Aldehyde 58 Optimization of Chelation Addition Investigation into the Deprotection of TMS-alkynes Pd-Mediated Hydrostannylation Attempted Bromo-alkyne Synthesis PMB Protection of Model Skipped Enyne Attempted Hydrozirconation of TMS-alkynes (I) Attempted Hydrozirconation of TMS-alkynes (ll) Attempted Hydroboration of Skipped Enyne 65 Stille Cross-coupling of Model System Pd-mediated Hydrostannylation of Enyne 68 Synthesis of Fragment ABD PMB Protection of Fragment AB Hydrolysis of ABD Ester 70 20 21 22 23 24 25 25 26 27 29 31 32 32 33 34 35 36 36 37 38 39 SCHEME46 SCHEME4Z SCHEME48 SCHEME49 SCHEMESQ SCHEME5L SCHEMESZ SCHEME53 SCHEME54 SCHEME55 SCHEME56 SCHEME51 SCHEME58 SCHEME59 SCHEME6Q SCHEME6L SCHEME62 SCHEME63 SCHEME64 SCHEME65 SCHEME66 SCHEMEGI SCHEME68 TBS Protection of Fragment AB Acetal Hydrolysis of Fragment AB Derivatives Functionalization of AB trial 78 Hydrolysis of Early lnterrnediates Hydrolysis of Acetal 54 to give Biol 84 Attempted Fragment B Displacement 2"d Generation Retrosynthetic Analysis Selective Protective Group Functionalization of Diol 84 PMB Protective Investigation of 2° Alcohol 87 Vinyl Magnesium Bromide Addition (I) Conversion of Phenyl Sulfide 89 to Aldehyde 95 Vinyl Magnesium Bromide Addition (ll) Preparation of E-vinyl Stannane 102 Cross-coupling of Vinyl Stannane 102 and (Z)-vinyl Iodide 300 Attempted RCM (I) Preparation of RCM acyclic diene 107 Preparation of Alcohol 109 Preparation of Alcohol 109 via D-arabitol Vinyl Magnesium Bromide Addition (Ill) Preparation of Aldehyde 122 Preparation of (E)-viny| Stannane 125 Recycling of 1-bromo-alkyne by-product 4o 41 43 44 45 45 47 48 49 5o 51 51 52 52 53 53 54 55 56 56 57 58 Cross-coupling of Vinyl Stannane 125 and (Z)-vinyI Iodide 300 58 SCHEME69 SCHEME7Q SCHEME7L SCHEME72 SCHEME73 SCHEME74 SCHEME75 SCHEME76 SCHEME77 SCHEME78 SCHEME79 SCHEME8Q SCHEME8L SCHEMESZ SCHEME83 SCHEME84 SCHEME85 SCHEME86 SCHEMEBI SCHEME88 SCHEME89 SCHEMEQQ SCHEMEQL Attempted RCM of Diene 126 Preparation of (Z)-macrocycle 127 via RCM PMB Deprotection Investigation (I) PMB Deprotection Investigation (ll) Synthesis of the (Z)-amphidinolide A analog Cross-coupling of Vinyl Stannane 125 and (E)-vinyl Iodide 301 RCM of Diene 136 to give Truncated Ketone TMS Protection of RCM Diene Dimerization of Diene 138 via RCM RCM of Diene 136 to give (E)-macrocycle 140 Synthesis of the Assigned Structure of Amphidinolide A Preparation of RCM Substrate via L-arabitol (I) Preparation of RCM Substrate via L-arabitol (II) Preparation of RCM Substrate vial L-arabitol (III) Preparation of Diene 162 and Subsequent RCM Synthesis of 166, an Isomer of Amphidinolide A 3'd Generation Retrosynthetic Analysis Preparation of the Alder-ene Ruthenium Catalyst Preparation of Alder-ene Vinyl Stannane 174 Cross-coupling of Vinyl Stannane 174 and (E)-vinyl Iodide 302 Ruthenium Mediated Alder-ene Cross-coupling Investigation Ru-Mediated AIder-ene Cycloisomerization Investigation Indium Mediated Cyclization xi 59 60 60 61 62 63 64 64 65 65 67 69 70 71 71 72 73 74 74 75 76 78 SCHEME92 SCHEME93 SCHEME94 SCHEME95 SCHEME96 SCHEMEQI SCHEME98 SCHEME99 SCHEME1OO SCHEME101 SCHEME102 SCHEME 103 Proposed Stepwise Indium Diallylation Retrosynthetic Analysis of Model Macrocycle Synthesis of Model Vinyl Iodide 177 Synthesis of Model Vinyl Stannane 178 Cross-coupling of Vinyl Stannane 178 and (Z)-vinyl Iodide 177 Indium Mediated Cyclization Tin — Indium Transmetallation In Situ Buaan and Subsequent Hydrostannylation (I) . In Situ Buaan Stoichiometric TBAF . In Situ Buaan and Subsequent Hydrostannylation (II) . In Situ Buaan via Red-Sil . In Situ Meaan xii 79 79 80 80 91 92 Ac Acac AIBN AgNOa aq CH2C|2 Cl CSA DCC DBU DMD DEAL DMAP DME DMF DMSO a eq FAB hr LIST OF ABBREVIATIONS acetyl acetylacetonate 2,2’-azobisisobutyronitrile silver nitrate aqueous dichloromethane chemical ionization camphorsulfonic acid cyclohexyl dicyclohexylcarbodiimide 1 ,8-diazabicyclo[5,4,0]undec-7-ene diisopropyl azodicarboxylate diisobutylaluminum hydride 4-(dimethylamino)pyridine dimethoxyethane N,N-dimethylfonnamide dimethyl sulfoxide electric ionization equation fast atom bombardment hour xiii HMPA HRMS HWE lMES-Hz KHMDS LiHMDS m-CPBA mL mmol MS NaHMDS NBS NMP NOE Ph PMB RCM TBAF TBS THF TMS PTSA hexamethyl phosphoramide high resolution mass spectrometry Homers-Wadsworth-Emmons reaction 4,5-dihydrO-1 ,3-bis(2,4,6-trimethylphenyl)imidazoI-2-ylidene potassium bis(trimethylsilyl)amide lithium bis(trimethylsilyl)amide m-chloroperbenzoic acid milliliter millimole molecular sieves sodium bis(trimethylsilyl)amide N-bromosuccinimide N-methyI-2-pyrrolidinone nuclear Overhauser effect phenyl p-methoxybenzyl ring closing metathesis room temperature tetrabutylammonium fluoride t-butyldimethylsilyl tetrahydrofuran trimethylsilyl p-toluenesulfonic acid xiv Introduction and Prior Work: Marine microalgae are of considerable interest as new promising sources Of bioactive substances. The amphidinolides (A-V),1 isolated by Kobayashi from the marine dinoflagellate Amphidinium sp, represent a novel and significant class of natural products which originate from such algae. The amphidinolides have marked biological properties especially activity against L1210 marine leukemia cells and human epiderrnoid carcinoma KB cells in vitro as summarized in Table Table 1 - Cytotoxicity Data of Various Amphidinolides lactone Cytotoxicity Amphidinolide ring size (leo, pg/ml) L1210 KB A 20 2.0 5.7 J 15 2.7 3.9 K 19 1 .65 2.9 P 15 1 .6 5.8 N 26 0.00005 0.0006 1. Amphidinolide A (1), Scheme 1, isolated in 1986 was the first polyolefinic macrolide of this unique series of compounds to be identified.2 Since 1986 there have been over twenty-two of these unique macrolides isolated with the complete stereochemistry of only a few elucidated. The absolute stereochemistry:3 of amphidinolide A was elucidated in 1991 by one- and two-dimensional NMR; however, to date the proposed stereochemistry has not been verified by X-ray crystallography. In addition to its impressive anti-cancer activity, the 20-membered lactone (1), has several striking structural features, including the Scheme 1. Several Amphidinolides .09, H Amphidinolide J a-mphldinolide P presence of lipophilic and hydrophilic moieties as well as the presence of exocyclic olefins and both conjugated and non-conjugated dienes. Because of these structural and biological features amphidinolide A is a current target for total synthesis.4 To date no total synthesis of amphidinolide A has been reported. Amphidinolides J, K, and P have been synthesized by Williams.5 Although Mother Nature supplies us with millions of molecules, the quantity isolated is often only minute (< 1 mg). For detail biological studies, which are needed for understanding the mode Of action of the target compound, the minute quantities isolated are not sufficient. Since the natural source is often not the most efficient means of obtaining the target molecules, synthetic efforts are needed. The total synthesis Of natural products also allows for structure- activity relationship (SAR) studies. Often new synthetic methodology is developed or expanded to assist in the synthetic quest. In our approach to amphidinolide A (Figure 1), we were interested in the development or application Ring-closing F metathesis OH Chelation Stille Coupling controlled addition Amphidinolide A 1 Figure 1. Retrosynthetic Analysis of Amphidinolide A of organometallic reactions. Essential in the design of this synthesis was the generation and reaction of vinyl organometallics. For the synthesis of vinyl tins, it was proposed that palladium-mediated hydrostannylations be investigated.6 Two aims of such a study would be to determine what effect the presence of the non-conjugated olefin would have on the hydrostannylations and (b) could such a palladium-catalyzed reaction be developed into a single pot stannylation-Stille coupling? Besides adding expediency to the synthesis, a one-pot sequence could minimize side reactions such a protiodestannylation which Often occurs upon workup and isolation of vinylstannanes. Besides using the total synthesis of amphidinolide A to developed new methodology, we were also interested in the application of recently developed novel chemical transformations. In particular, ruthenium based macrocyclizations were investigated in our second and third generation approach to the natural product. The first ruthenium-based macrocyclization to be investigated was the ring-Closing metathesis (RCM) reaction, which has developed into a powerful synthetic tool with the advent of well-defined carbene catalysts by Grubbs.7 In our third generation approach, an intramolecular variant of an Alder-ene type cross-coupling8 was investigated. To date only two other groups in addition to ours have reported synthetic efforts towards amphidinolide A. The first was Williard in 1989.9 Williard’s work Scheme 2. Williard's Approach TBSO SOZPh * KM/OMOM 4 o o 6 OCH3 >5 was prior to the stereochemical elucidation and therefore in his approach (Scheme 2) to the C10 - C19 fragment 2, methodology was developed to prepare all possible stereoisomers of 2 in order to make an unambiguous assignment of the stereochemistry. From his reaction sequences, the other stereoisomers could be readily available by changing chirality of the starting materials. The optically pure ester 3 is readily available as either enantiomer from (+)- or (-)- tartaric acid. Sulfone 4 is prepared from commercially available S-(+)-methyI-3- hydroxy-2-methylpropinate, whose enantiomer is also commercially available. More recently, Williard presented a poster at the 221St ACS National Meeting in San Diego detailing his current synthetic approach to amphidinolide A.10 The second group to take on the task of synthesizing amphidinolide A was Pattenden.11 In 1994, Pattenden published his first of two reports on amphidinolide A. In his first report (Scheme 3) a model study was undertaken to 4 investigate the feasibility of a cross-coupling macrocyclization as a key step in the construction of (1). In particular, the chemical transformation investigated Scheme 3. Pattenden's Model Study Cl / / BU3Sn Pdgdbaa Pths / / O (38%) / / 0 0 5 5 was a palladium mediated intramolecular coupling of an alkenyl stannane and an allylic halide. The methodology proved moderately successfully when applied to the model amphidinolide A system 5. The desired macrocycle 6 was obtained in a 38% yield along with the Z-isomer (6%) and the allylic isomer (2%). Pattenden outlined his actual synthetic Scheme 4. Pattenden's Retro-analysis approach (Scheme 4) toward the natural product, in a second publication. The underlying theme (proposed subunit) . . / OR of the retro-anaIySIs IS the 7 BUasnm O _ . . (proposed subunit) appIIcatIon of the above-mentioned sp2 - spa coupling methodology. In these studies he prepared the properly functionalized C7 — C13 ene-tetra-ol unit 7. This subunit was prepared from a known readily available derivative of D-glucose in 13 linear steps with an overall yield of 2%. Chapter 1. 1“t Generation Approach — Synthesis of Fragments Our initial retrosynthetic breakdown of amphidinolide A (Scheme 5) afforded four fragments A - D and illustrated the main synthetic challenges of this molecule. Several issues guided our retrosynthetic plan. These included the formation of multiple stereocenters early in the synthesis, the development and Scheme 5. Amphidinolide A Retrosynthetic Analysis Chelation controlled addition E! TMS Nucleophilic 5‘ \ on addition 0 \ Br HO 8 p \ OPMB New / “-:° c Esterification 8' . on m / TMS Chelation Stille coupling 0 H00" HO o o c z - “c 23333:.“ evaluation of new synthetic methods, and maintaining a flexible approach to the target molecule. Furthermore, the successful construction of subunits A - D would allow us to simultaneously investigate multiple coupling strategies, providing valuable information as to which coupling sequence should be employed in our final elaboration of amphidinolide A. The overall synthesis was envisioned to involve the independent couplings of common precursor B to molecules A and C, followed by the coupling of the resultant products. Compound D was expected to be added last via a Stille coupling12 followed by macrolactonization to close the ring. A. Synthesis of Fragment A In our retro-synthetic analysis of fragment A, the 1,2-epoxy-3-ol 11 is a key advanced intermediate and thus several routes towards its synthesis were investigated. In all cases, the starting chiral source was D-mannitol. 1. D-Glyceraldehyde Acetonide Approach D-glyceraldehyde acetonide is readily available via the oxidative cleavage of the bisisopropylidene acetal of mannitol.13 The success of the oxidative cleavage in our hands depended on reagent choice. Following a procedure, which called for sodium periodate as the oxidant (Scheme 6) the desired aldehyde 9 was isolated in low yields (~37°/o). Although the setback was early in the synthesis, alternative oxidants were probed. With the use of lead (IV) Scheme 6. Synthesis of 1,2-epoxy-3-ol (11) 0%0 9H Ngtllgaa Ar 0% ’Xfi We (37%) H .9 o % M913t .F 0 SAE o .9 o - or ’ YV —.O°C,Et20 M —‘* WV 5H 0 Pb(OAc) Wk (53%) ‘ 0 (80%) 0” OH 3 9 10 11 tetraacetate as the oxidant, glyceraldehyde acetonide 9 was obtained in a moderately good yield (53%). Addition of vinyl magnesium bromide to the isolated aldehyde was not stereoselective. As a result, secondary allylic alcohol 10 was isolated as a mixture of diastereomers in 80% yield. The diastereomeric mixture was not problematic strategically since this stereocenter would be lost in the ensuing oxidation and olefination. With isolation of allylic alcohol 10, the target 1,2-epoxy-3-ol 11 was only a Sharpless asymmetric epoxidation away. This one step proved to be quite challenging. In an effort to make the purification and identification of the epoxy alcohol easier, the epoxidation was run under kinetic resolution conditions with (-)-D|PT as the chiral ligand. Unfortunately, epoxy alcohol 1 1 was isolated in very low yields (~5%). Attempted optimization of the reaction i.e. distillation of reagents, addition of molecular sieves, stoichiometric reagents, or increased reaction temperature, proved fruitless. Furthermore, upon purification of the reaction mixture, very little starting allylic alcohol was recovered. These results were quite baffling since the epoxidation of the enantiomer of 10 under kinetic resolution conditions is reported to occur in a 56% yield.14 One possible explanation for this phenomenon is that the tartrate-allylic alcohol complex is an unfavorable mismatch case and thus unproductive complexes are formed. Although the yield was not synthetically useful, the isolation of epoxy alcohol 11 was beneficial since spectroscopic data were obtained. 2. Trial Approach Since the above route to epoxy alcohol 11 was not preparatively viable, an indirect route to A through known triol 1515 was also investigated. The synthesis of triol 15 (Scheme 7) began with the oxidative cleavage of 8.16 The newly Scheme 7. Synthesis of 2,3-epoxy-1-ol (14) 0% Ti(O-i-Pr)4 0% Nal04, then : (+).DET F 3 —-—-—. HO ' O go 9 RM f-BuOOl-l \/5\\/\/ >AVC0251 (56%) 5‘0 DIBAL 12 R = C028 14 (94%) (75%) 13 R = CH20H generated aldehyde 9 was then subjected to an in situ Homers-Emmons olefination to give allylic ester 12. DIBAL reduction of the ester provided allylic alcohol 13 in 85% yield over three steps. Sharpless asymmetric epoxidation of 13 gave 2,3-epoxy-1-ol 14 in a 56% yield with complete stereocontrol as judged 8 by 1H NMR. Although the epoxide opening of 14 with aqueous NaOH is a known procedure, in our hands the procedure was nonreproducible (Scheme 8). We believed that the solubility of triol 15 in water was the major reason. In efforts to optimize the reaction, a biphasic system (t-BuOH / water) with a phase transfer catalyst (n-Bu4Nl) was employed, but to no avail. However, with a notion that triol 15 was formed but the isolation was problematic, the subsequent reaction Scheme 8. Attempted Moffatt Epoxidation o 0” 93K M°>99%) after equilibration with alcohol 11 (Scheme 9). Unfortunately, in our case the minor isomer was the desired Scheme 9. Model Payne Rearrangement compound, and therefore 0% 03f : aqueous O F . . Ho _ " ° ‘ ' non-aqueous conditions were \/5\\/\/ Payne rearrangement M OH . . , 14 11 Investigated (Scheme 10). Simply major minor quenching the equilibrating alcohols (t-BuOK, n-Bu4Nl) with water or TMSCI gave inconclusive results after isolation and purification of products. Therefore, quenching with other electrophiles was looked at. The use of pivalolyl chloride as the trapping Scheme 10. Non-aqueous Payne Rearrangement electrophile proved to be the most successful in FBUQK 14 n-Bu4Nl inclusive data terms of identification of isolated products. THF Contrary to precedent, the “presumed” 1, ”9.,” 9.\/ ' ‘ ' 1‘ 2. 1:33: HOMO equrlibratlon of epoxy alcohols 11 and 14 under (32%) e‘ non-aqueous conditions gave identical results as the aqueous Payne rearrangement. Although the direct isolation of the 1,2-epoxy-3-ol 11 via the Payne rearrangement is not possible, Sharpless has developed a procedure which utilizes the Payne rearrangement to obtain the minor epoxide.19 In an extensive study, he showed that exposure of 2,3-epoxy-1-ols to the equilibrating conditions of the Payne rearrangement can result in selective opening of the terminal epoxide upon the addition of t-butylthiol. It was found that the product distribution is affected by several factors including sodium hydroxide concentration, reaction temperature, and the rate of thiol addition. Upon exposure of 14 (Scheme 11) to the equilibrating conditions (0.5 M NaOH, 70 °C) and slow addition (~ 45 minutes) of t-butyl thiol, the expected diol 17 was isolated in good yields (75%). To obtain the desired 1,2-epoxy-3-ol (11), 17 must be selectively S-methylated (MeaOBF4) which is then followed by intramolecular displacement of methyl t-butyl sulfide by the in situ generated (NaH) neighboring oxygen anion. This sequence of reactions is worthy of additional comment. Due to the acid labiality of the acetonide, a proton scavenger was needed during the methylation step. 10 Upon substituting 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 2,4,6- trimethylpyridine for 2,6-di-tert-butylpyridine, the material isolated after the addition of MeaOBF4 and NaH was either recovered starting material or unidentifiable mixtures presumably from acetal hydrolysis. When the reaction was repeated in the presence of the reportedly preferred 2,6-di-tert-butylpyridine, the desired epoxy alcohol was still not isolated. It is believed that the epoxy alcohol was decomposing during silica gel chromatography because TLC analysis suggested that a reaction was occurring. Based on the assumption that Scheme 11. lntramolecular Sulfide Displacement Investigation OH 9% 0.5 M N OH .= ' ' 14 __a__> t-BuS\/'\/\/O conditions a, b' c, or d > no desired product t-BuSH 5 6H 17 conditions: (a) DBU, M9308F4, NaH (b) 2,4,6-trimethylpyridine, M6308F4, NaH (c) 2,6-di-tert-butylpyridine, M9308F4, NaH (d) (1) 2,8-dl-tert-butytpyridine, Me308F4, Nat-t; (2) PivCl, pyridine the epoxy alcohol 11 was unstable on silica gel, the crude “presumed” epoxy alcohol was subjected to a pivalolyl protection. Unfortunately, the desired protected epoxy alcohol was not isolated after purification. To alleviate the potential instability of 1,2-epoxy-3-ol (11), the acid labile isopropylidene protecting group was replaced with the more stable isopentylidene analog.20 11 This synthesis began with the bisisopentylidene of D-mannitol via an approach which largely paralleled the above procedures for the preparation of Scheme 12. Synthesis of 2.3-epoxy-1-ol (21) Et Et 5: Et $0 OH 0 Et Tl(O-i-Pf)4 0%Et o g KIO4, then : (+)-DET .= —.—__. ' O a o 0 RM t-BuOOl-l HOW 6H 0+5, E‘°;che,a (73%) E1 80 DIBAL 19 R = C0251 21 1a (90%) 20 R = CH20I~| the isopropylidene analog. As illustrated in Scheme 12, bisisopentylidene 18 was oxidatively cleaved by KIO4 and then subjected to an in situ Wittig olefination. DIBAL reduction of the resultant ester 19 provided allylic alcohol 20 in 85% yield over three steps. Asymmetric epoxidation of 20 gave 2,3-epoxy-1-ol 21 with complete stereocontrol. With the isolation of the isopentylidene variant of the 2,3-epoxy-1-ol, the previously problematic three step procedure aimed at obtaining the 1,2-epoxy-1-ol via the 2,3-epoxy-1-ol was investigated. Subjection 0' epoxy alcohol 21 (Scheme Scheme 13. Payne Rearrangement and In 13) to the Payne 8”" Opening 5! . . Et rearrangement conditions and MM N80,, musk/<0 Me308F4 : 21 t-BuSH 5 2,6.di-t-butyl pyridine slow addition of t-butyl thiol (57%) 0“ "‘°" ”3“ 22 resulted in isolation of diol ’ a q E: 9%5‘ 1. Swem[O] 9.3(5‘ sulfide 22 in a 67% yield. Due Mo ——‘2. Pnapcuz We to problems in isolating the 23 25 " ‘ (10 - 20% yield, 3 steps) isopropylidene 1,2-epoxy-3-ol analog, purification of the isopentylidene epoxide was not attempted until after oxidation and Wittig olefination. As such, diol sulfide 22 was selectively 12 S-methylated with MeaoBF4 in the presence of 2,6-di-tert-butyl-4-methyl pyridine and after TLC analysis indicated complete consumption of the sulfide NaH was added to generate the alkoxide for the intramolecular displacement. The assumed crude 1,2-epoxy-3-ol 23 was subjected to a Swem oxidation21 to give the apparent ketone 24, which was in turn subjected to Wittig olefination. These successive reactions did indeed give the desired allylic epoxide 25 (~10% overall yield) after purification by flash chromatography on basic alumina. After substantial experimentation, the overall yield of the three tandem reactions was increased to only ~20%. Unfortunately, a low yield at this stage of the synthesis was not acceptable, and therefore each individual step was investigated. As illustrated in Scheme 14, optimization of the S-methylation / intramolecular displacement procedure with diol sulfide 22 gave the 1,2-epoxy-3-ol (23) in reproducible yields of 75%. Obviously, the above results suggest that one or bOth 0f the latter Scheme 14. Isolation of 1,2-epoxy-3-ol (23) reactions in the three 5‘ Et M6308F4 O 9%8 a, b, or c o 9% Et , o 2,6-di-t-butyl pyridine M 22 A -‘ _. r 0 reaction sequence was man NaH 3 WV H 7 °o (53/) 23 25 Conditions: (a) (i)Swem. (ii) PhaPCHQ; 41% yield, 2 steps (b) (i) Doss-Martin, (ii) Ph3PCH2; 29% yield, 2 steps (c) (i) Doering-Pan‘kh, (ii) Ph3PCH2; 25% yield, 2 steps the reason for the overall low yield. Therefore, the tandem oxidationNVittig olefination procedure was investigated. When investigating the tandem reaction, a Swem, Dess-Martin,22 or Doering- Parikh23 oxidation followed by subsequent Wittig olefination gave allylic epoxide 25 in 41%, 29%, and 25% yields, respectively. Since the oxidation/olefination tandem protocol is well established, and the above results are fairly consistent, 13 the olefination reaction was likely the low yielding step. This indeed turned out to be the case (Scheme 15) as the Doering-Parikh oxidation gave ketone 24 in an 80% yield. In our earlier Wittig olefination procedure, n-BuLi (1.1 equivalents) was the base used to form the ylide of methyltriphenylphosphonium bromide (1.1 equivalents). In our optimized procedure it was found that NaHMDS (5 equivalents) and excess methyltriphenylphosphonium bromide (5.4 equivalents) gave the desired allylic epoxide 25 in excellent yields (83%). As a note, we also believe that the addition of the ylide to the carbonyl is a fast step, but the breakdown of the 4-membered ring intermediate is slow because the starting Scheme 15. Optimization of the Oxidatin and Wittig Olefination Et E1 E1 9%51 9%51 gist MO a, b. or c O ? 0 NaHMDS (5.0 equiv) ‘ O 3‘ a |>\n/\/ Ph3PCl-l38r (5.4 equiv) OH 0 o (83 lo) 23 24 25 Oxidation: (a) Doering-Parikh, 80% yield (b) Dess-Marin periodanano, 24% yield (c) TPAP, NMO, 0% yield material is consumed within minutes. Yet, only upon extended reaction times (~3 hours) was exo-olefin 25 isolated in high yields. With the establishment of high yielding and reproducible procedures for the synthesis of these advanced intermediates, the synthesis of fragment A was carried fonivard. As illustrated in Scheme 16, epoxide 25 was opened regioselectively with sodium benzenethiolate to give phenyl sulfide 26 in 65% yield. In preparation for a Pummerer rearrangement, oxidation of sulfide 26 with m-CPBA gave the corresponding sulfoxide which was immediately rearranged (AczO, NaOAc, reflux).24 This allowed for isolation of acetoxy sulfide 27 in 36% yield as a 14 mixture of diastereomers. , , Scheme 16. Preparation of a-acetoxy sulfide 27 Acetoxy sulfide 27 IS a 61 E1 masked aldehyde and o PAVE 0” 9&8 .~ 0 PhSNa P118 1. m-CPBA : . ‘>\"/\/ THF 2. A020. NaOAc upon reduction of the (65%) (35%) 25 26 Et esters with DIBAL the 5, GAO 9%8 OH QAVB -‘ o aldehyde would be new 37% HMO ON: 0 expected to be liberated 27 28 without epimerization of the a-stereocenter. In contrast, subjection of the acetoxy sulfides to DIBAL reduction did not give the desired aldehyde, but instead a product that probably is derived from a 5-endo cyclization of the highly reactive dianion intermediate. To circumvent this highly reactive dianion intermediate (Scheme 17) the alcohol of phenyl sulfide 26 was protected as a silyl ether prior to oxidation and subsequent Pummerer rearrangement. It was found that the protection of alcohol 26 to give silyl ether 29 in 75% yield had to be carried out at -78 °C with TBSOTf in order to avoid a side reaction that occurred if the protection was carried out at room temperature and/or with bulkier silyl protective groups, i.e. BPS. Interestingly, at room temperature, a TBSOTf / i-PerEt solution could be used as a quench after the epoxide opening of 25 to give the desired silyl ether 29 (55%) along with unprotected alcohol 26 (36%) and recovered starting epoxide (9%) with no indication of side reactions. Exposure of sulfide 29 to m-CPBA gave sulfoxide 30 in near quantitative yield. The crude sulfoxide was subjected to the Pummerer rearrangement (A020, NaOAc, reflux) to give a 15 Scheme 17. Isolation of Fragment A Et Et ores 9%3 o ores 9%5‘ F o " r o TBSOTf phs m-CPBA Phs NaOAc ~ A 0 were: (>98%) [affix '78 C (40%) (75%) . 29 30 (55% yield. 2 steps) E1 E! E! ores 0%5‘ ores g 5‘ ores 0 Sta _.= DIBAL ; 5 O -——————> O PNSW/ '78 cc HO\/k[(\/ + HWV CM 0 31 32 33 (14%) (15%) diastereomeric mixture of acetoxy sulfide 31 in a 40% yield. DIBAL reduction of acetoxy sulfide 31 led to the target aldehyde 33 (15%) along with the corresponding fully reduced product, alcohol 32 (14%). 4. Improved Synthesis In efforts to streamline the synthesis of fragment A, we decided to open the equilibrating epoxy alcohols of the Payne rearrangement with thiophenol instead of t-butylthiol. This would directly set up the molecule for the ensuing Pummerer rearrangement. In practice (Scheme 18) this tactic provided sulfide 34 in a 69% yield. However, this synthetic approach can only be useful if the newly formed diol is selectively mono protected. Somewhat surprisingly, the C-2 hydroxyl could be mono protected with TBSOTf to give TBS ether 3525 in 69% yield along with disilylated material (10%) and unreacted diol (17%). A Doering- Parikh oxidation gave ketone 36 and subsequent reaction with Ph3P=CH2 (NaHMDS, PhaPCHaBr) efficiently installed the exo olefin of 29. After the quantitative oxidation of sulfide 29 with m-CPBA the Pummerer rearrangement of sulfoxide 30 was investigated. Instead of the harsh conditions of refluxing acetic 16 anhydride, a milder procedure utilizing a mixture of trifluoroacetic anhydride26 and acetic anhydride in the presence of 2,6-lutidine at room temperature gave the desired diastereomeric mixture of acetoxy sulfide 31 in 80% yield. Unmasking of Scheme 18. Streamline Synthesis of Fragment A E1 OH 9'\/Et 0.5 M NaOH ——-————» pns\/l\/?\/o 1&1. - FszNEt Et OTBS 9.3(6‘ ‘ 0 Sanpyr PnS \/'\/\/ PhSl-l DMSO 0 _ o ; i-PrgNEt (69 /o) OH (59 /°) 0“ (72%) 34 35 er E El ‘ ores 1r ores o—\’ 0 0735 9’: -T——>FAA :9 Ph3P=CH2 m-CPBA l' phs . O ———> PhS \/'\"/\/ (90°—_/—’o) (>95%) 26 6"“ o (80%) 36 Et a er E E, ores o ores QJS LiBEtgH; NH,CI; HO 5 Ag SwemIOI OTBS 9&8 MS ' glycerol (93%) H ‘ (79°/o) OAc 31 32 “(33’ the aldehyde was accomplished in 70% yield by a lithium triethylborohydride (Super-Hydride®) reduction giving alcohol 32. Subsequent Swem oxidation provided target aldehyde 33. It is worth noting that during the initial experiments on the Super-Hydride® reduction of 31 (Scheme 19) aqueous NH4C| workup led solely to the isolation of an unhydrolyzed organoborane Scheme 19. Super-Hydride Workup species (37) as indicated by a e a ores 9%5‘ onz 9%5‘ PhS we SUper'hydride R10\An/r\/o OAc workup (a-c) resiliency of the organoborane to 3‘ 31 37'” (8) aqueous NH4CI; 37 [R1=BR2, R2=TBS (95% crude yield)] (b) aqueous NaOH: 32 [R1=H, R2=TBS (49%) + 38 [R1=TBS, R2=H (25%)] (c) aqueous NH4CI. then glycerol; 32 [R,=H, R2=TBS (75%)] t27 green flame tes . Given the mildly acidic conditions, we 17 attempted a basic workup. While treatment with aqueous NaOH did bring about complete removal of the boron, it also resulted in partial migration of the TBS group to the primary alcohol 38. In the end, we found that a combined NH..CVglycerol28 workup afforded high yields of alcohol 32 without migration of the silyl ether. This revised synthesis of fragment A involves a total of 11 steps from readily available bisi30pentylidene 12 with an overall yield of 12%. Besides eliminating 2 steps, the revised synthesis eliminates the need to isolate the labile 1,2-epoxy-3-ol (23). B. Synthesis of Fragment B We anticipated the need for multigram quantities of subunit B as it is a common building block for both the upper and lower hemispheres of amphidinolide A. Somewhat surprisingly, this relatively simple molecule had yet to be described in the literature. With hindsight this should have suggested a nontrivial synthesis. However, our earlier synthetic endeavors began with straightforward approaches (Scheme 20). The starting trimethylsilylacetylene, although commercially available, was easily prepared from ethynyl magnesium bromide and trimethylsilylchloride. However, due to an almost impossible distillation from THF’ the target compound Scheme 20. Attempts Toward Known Diyne 39 Sr TMS TMS—I —_%.a °'b V “EB-r» WT” 39 8 conditions: (a) (i) ethynylmagnesiurn bromide (ii)CuCl (iii) propargyl bromide (b) (i) n-BuLi (ii) CuCN (iii) propargyl bromide was used as a THF solution. With the isolation of 18 trimethylsilylacetylene secured, the reaction to obtain diyne 39 was investigated. Unfortunately, diyne 39 was not isolated via the adapted literature procedure,29 as well as, several variations. Scheme 21. Unsuccessful TMS-acetylide With the failure of the copper Displacement Bf 0°/o Br . . TMS : M + fix —> W mediated Grignard huh/'98“ \ ms X=Br,l B displacement, a direct cuprate displacement was also investigated but with no success. Simultaneously, efforts were directed toward the displacement of both 2,3-dibromo- or 2-bromo-3- iodopropene by either the lithium, sodium, or potassium TMS—acetylides (Scheme 21). However, neither changing the metal nor varying the reaction conditions gave fragment B. Our next attempt at the synthesis of subunit B involved the addition of trimethylsilylacetylene to 2,3-dibromopropene under phase transfer conditions (Scheme 22).30 Disappointingly, these two reactants, which individually were efficiently employed in similar reactions, failed to couple. Research efforts then Scheme 22. Phase Transfer Conditions Toward Subunit B Br CuI 8r H + \n/\B' n-BuflNI § K2003 so % 4o Cul 1’ I n—Bu4NI < >—__: . H 2 K2003 I 2,3-dihalopropene but the metal 73% 41 Cul salts were now converted to "‘3 :43;qu "“8 Z I 83 °/o 42 returned to the use of trimethylsilylacetylide metal salt displacements of if)? I + r5- cuprate species as seen in our Br Br __ Br ms __ H + \[l/\ n-BusNI W K2003 TMS Scheme 23. With the use of 0% B CuCN, CuCI, and GUI as the copper source the formation of a cuprate species was not in question since copper salts are insoluble in THF while cuprates gave a homogeneous solution. The presumed cuprate species were unreactive toward 2,3-dihalopropene from —78 °C to 25 °C. Finally, after considerable experimentation, we discovered copper assisted Grignard conditions which ultimately provided gram quantities of B in 83% - 95% yield. For formation of the Grignard species of trimethylsilylacetylene heating (~55 °C) was found to be crucial. The reaction was then allowed to cool to room temperature after which CuBr was added. The reaction mixture was then heated to 50 °C, followed by the dropwise addition (~3 hours) of 2,3-dibromopropene. This sequence finally resulted in the formation of subunit B. Scheme 23. Synthesis of Fragment B Initially, we thought that the success of CW Y=CN on I 3' TMS : Ll ——’——‘> \ the reaction was due to the copper (l) °'\n/\x \fl/B\ms - , 0°0 source instead of the reaction procedure. “a" / Ho 9 't sf dtht 'th C CN 1' 8W W van: wa oun a e: er u o°c.so°c r ms : H 2. CuBr, RT 8 W . . —> TMS or Cul could be substituted for CuBr wrth 3T», ' 83% a . no lost in reactivity or yield. This indicated that temperature modulation was key. Finally, the stability of fragment B proved to be a non-issue, as after several months of storage, 8 showed no signs of decomposition by 1H NMR. 20 C. Synthetic Studies Toward Fragment C Prior to our synthesis of fragment C, (S)-2-methylpentan-1-ol 4731 was known. However, as we planned to employ an Evans aldol reaction to generate what would ultimately become the C-18 and C-19 asymmetric centers of amphidinolide A, it was decided that an iterative chiral auxiliary based approach to all of the stereogenic carbons in C would make for the most efficient synthesis of that fragment. The synthesis of fragment C (Scheme 24) began with the preparation of the Evans’ oxazolidinone chiral auxiliary 44. Upon exposure and heating of the commercially available (1 S,2R)-norephedrine HCI salt to K200;; and diphenyl carbonate, the desired oxazolidinone 43 was isolated in a 51% yield. The oxazolidinone was acylated by deprotonation with n-BuLi and subsequent Scheme 24. Synthetic Approach to Fragment C CH 2. K2003 (51%) . '2, e 43 (970/60) EH, 0 NH3*CI‘ 1- (CGHSO)2CO OANH 1. n-BuLi OJL UNJCL‘ ”13.—J :Me O 1.NaHMDS 0A NW ”I202 37 + How 51, 2. CH2=CHCH2l GNU 2- U0“ CH (92°16) 5' .’, 3 Ph Me 46 4s 1. LiAIH‘ W 2. H2. Pd/C ”0 1 CH3 47 addition of propionoyl chloride gave the desired chiral auxiliary 44 in an excellent yield (97%). With the isolation of the chiral auxiliary, several asymmetric alkylations were investigated. Initially, alkylations were attempted with the 21 relatively unactivated electrophile, propyl chloride. These failed.32 Therefore, the chiral auxiliary was alkylated with alIyl bromide or iodide, to afford 45 in a crude yield of 92%. The chiral auxiliary was oxidatively cleaved with H202 and LiOH to give recovered oxazolidinone 43 and acid 46, which was immediately reduced with LiAIH4 and subsequently hydrogenated to give (S)-2-methylpentan-1-ol 47. The above series of reactions were run once, and therefore the yields are not optimized.33 D. Synthesis of Fragment D The known B-iodo acid D is readily available from ethyl 2-butynoate as illustrated in Schemes 25 and 26.34 The alkyne was added to a sealed tube containing hydriodic acid (48% aqueous) and heated to 110 °C. After 12 hours, the reaction was allowed to cool to room temperature at which time the crystalline carboxylic acid 48 which had precipitated from solution was filtered off, and the remaining filtrate which contained unhydrolyzed ester 49 (38%) was subjected to reaction conditions where the ester hydrolysis was nearly quantitative. This recycling protocol afforded B-iodo acid 48 in an 80% combined overall yield. In terms 0f Scheme 25. Synthesis of Fragment D (I) throughput, this process turned HI. H20 110°C (100%) out to be more efficient than Me . . \\ 08 HI, H20 running the reaction to 110°c ' / O (sealed tube) completion in a single pass. “(427) “(mi As reported, isomerization of the double bond was achieved with heating at 135 °C. In our hands, the isomerization of (Z)-j3-iodo acid 48 to the desired (E)-B-iodo 22 aCId D was high yielding but only afforded a 3:1 Scheme 26. E/Z ratio. The ratio consistently remained 3:1 lsomerization 0f ACidS 0 even with prolonged heating or addition of 0“ 135°C l / OH . ' / W aqueous HI. Fortunately, the isomers could be 48 0 E/Z(3:1) separated by careful flash chromatography on silica gel. Although the experimental procedure for obtaining B-iodo acids was straightforward, the “cis-trans” nomenclature assignment in the Le Noble communication is confusing and resulted in an early misinterpretation35 as to which B-iodo acid, i.e. 48 or D, was initially obtained. This was not clarified until late into our synthetic venture. Therefore, all of our earlier work with the B-iodo acid was with the undesired (2)-isomer. Our synthetic efforts toward the naturally occurring amphidinolide A (1), and its C2 — Ca Z-isomer analog will be presented. 23 Chapter 2. Coupling and Elaboration of 1" Generation Subunits The successful construction of subunits A-D allowed us to simultaneously investigate multiple coupling strategies and in tum provided valuable information as to which coupling sequence would be employed in our final elaboration of amphidinolide A. A. Coupling of Fragments A and B A chelation controlled addition of an organometallic derived from B to A was planned for the union of A and B. Organometals examined included organolithium, organomagnesium, and organozinc species. In our studies, the Grignard reaction proved to be the most successful. TBS-protected subunit A can not undergo chelation controlled addition; although the desired threo-diol could be obtained from Grignards if the addition occurs under the Felkin-Ahn model (Figure 2) WSW with the vinyl appendage acting as the large Nu/H Figure 2. Felkin-Ahn Model H group. As such, aldehyde 33 (A) was investigated in our early studies. Prior to an investigation of the stereoselectivity of the nucleophilic addition, a reliable protocol for the formation of a metallated B species need to be established. As such, the formation of the Grignard reagent of fragment B was investigated. The vinyl Scheme 27. Attempted Grignard Formation Br \n/\ K 1- TMS toward several types of MgCI2 _. [Mg] 0 2 No Grignardiormaiion NaI recovered halide 2. bromide was unreactive H magnesium tumings as 24 apparent by the recovered halide. Therefore a more reactive form of magnesium was examined (Scheme 27). Rieke developed conditions to form a highly reactive Mg° species through the reduction of magnesium salts.36 Several attempts to generate the organomagnesium under these conditions were tried. The reduction of MQCI2 with potassium metal showed characteristics traditional for Rieke conditions; however, upon isolation of the reaction mixture the Grignard formation was clearly incomplete (<1%) since vinyl bromide B was recovered. The reaction was futile even with the addition of NaI, an additive that is known to accelerate the formation of Grignard reagents from sluggish substrates such as alkyl fluorides. Scheme 28. Coupling of Fragment B and Valeraldehyde OH OH TMS Br 1. t-BuLi. // \ __. + \ MgBr2° Et20 \ TMS 2. valeraldehyde \ TMS \ (55%) (32%) Although the lack of reactivity of fragment 8 under Grignard-forming conditions was discouraging, efforts at forming a metallated species continued. After considerable experimentation a transmetallation protocol was discovered to give the Grignard (Scheme 28). First, vinyl bromide B was converted to the lithium derivative Scheme 29. Mechanism of By-product Formation by a halogen- B . ‘M r“ f-guLi \n/\ + ——Br -0 H _ metal exchange we ”93'2°E‘2° ms 4 *3 OH (t-BuLi, -78 °C). e R “W t-BuLi “\n/\ E2. Hj‘J/\ Once formed, the \ ms \ TMS \ TMS by-product lithium derivative was converted into the magnesium species by transmetallation 25 with MgBrgoEtzO. Upon addition of valeraldehyde, two products were isolated in an excellent yield, the desired alcohol 50 (55%) and a by-product alcohol 51 (32%). The by-product (Scheme 29) comes about because the metallated vinyl species acts as a base and deprotonates the t-butyl bromide generated in the reaction mixture. The newly formed alkene is then deprotonated at the acidic allylic carbon by excess t-BuLi and the resultant anion adds to the aldehyde giving by-product 51. Although the above procedure was not optimized and gave a considerable amount of a by-product, the coupling protocol was tested with the amphidinolide A subunits. In practice the coupling of fragments A and B (Scheme 30) was not as clean as the model reaction. Furthermore, upon purification of the reaction Scheme 30. Coupling of Fragment B and Aldehyde 33 (A) E! ores 5% a, 1. t-BuLi, OTBS 9%8 9 W MgBrgoEIQO “‘5 2 aldehyde33 OH 3 (25%) (1: 1) 53 mixture two separable diastereomers (1:1) were isolated indicating that there was no significant steric bias in this system. Besides not being stereoselective. the reaction also produced the undesired allylic addition product, as was seen in the model study. Several modifications to the reaction procedure were investigated to increase the stereoselectivity of the addition, and to eliminate or suppress the side reaction. To suppress the side reaction, the rate of addition of t-BuLi was increased and the order of addition of t—BuLi and vinyl bromide B was reversed. The latter proved to be the most successful. With the reverse addition of reagents, the transmetallation reagent (MgBrzoEtzO) had to be changed due to 26 several complications i.e. poor solubility and the addition of a solid. The new reagent of choice for the transmetallation was a toluene solution of dimethylzinc (ZnMeg).37 Secondly, given the poor stereoselectivity of the coupling with the TBS-ether derivative of aldehyde A, a more desirable chelating ether was needed. The PMB derivative of fragment A was chosen. The PMB ether derivative of fragment A is readily available (Scheme 31) with slight modifications of our original synthesis of aldehyde 33. Deprotection of TBS-ether 29 with TBAF (90%), followed by protection of the free hydroxyl as the PMB-ether (NaH, PMBCI, DMSO/T HF) (85%) gave protected alcohol 54. Analogous to the TBS series, oxidation of the sulfide to the sulfoxide 55 with m-CPBA (100%), followed by subjection of the crude mixture to a Pummerer rearrangement (T FAA, Ac20, 2,6-Iutidine) (80%) and reduction of the Scheme 31. Synthesis of the PMB Derivative of Fragment A E1 E1 E1 E1 a 1. m-CPBA (100%) E1 OTBS 9% M OWE QAS 2. TFAA. Acao. 2.6-Iut. (30%) y OPMB 9 S r o 2. e NaH,DMSO -‘ V -‘ Phs a; PMBCI, THF Phs 3' ”35'!" (9“) Ho (90%) 29 54 57 Et Et Et OPMB 0%51 OPMB geie‘ OPMB 9%5' H O ? 0 oxidation ”W + H \ r O O 57 58 59 Swem (small scale) 76% ‘ Swem (large scale) 17% 52% Doering-Perikh - 83% Does-Martin 90% ‘ diastereomeric a-acetoxy sulfide 56 mixture with LiBEtgH (90%) gave alcohol 57 the precursor to aldehyde A. Unlike the TBS series, the oxidation of the aldehyde precursor under Swem and Doering-Parikh oxidation was problematic. 27 Oxidation of alcohol 57 to aldehyde 58 was successful under Swem conditions on a small scale; however, upon scale-up enal 59 was seen as a minor product (Scheme 31 ). Moreover, after column chromatography on silica gel, enal 59 was the major isolated product. With the Doering-Parikh oxidation enal 59 was the only product as indicated by TLC and 1H NMR of the crude mixture. Fortunately, internalization of the olefin was suppressed under Dess-Martin conditions, giving the desired aldehyde 58 in excellent yields (>90%).38 With the appropriate aldehyde in hand, the addition of a metal species of fragment 8 to aldehyde 58 under chelation conditions was investigated. Before coupling B with the PMB-variant of fragment A, a new experimental procedure was sought which would suppress the above mentioned side reactions. A new experimental procedure, which consisted of the addition of vinyl bromide B to the t-BuLi solution and ZnMez as the transmetallating reagent, was successful. In our model study (Scheme 32) the desired alcohol 50 was isolated in excellent yields (92%) with none of the earlier by—product. More Scheme 32. Diastereoselective Coupling of Fragment B and Aldehyde 58 3' i-euu. ZnM62 \n/\ '780C : a TMS then valeraldehyde \\ TMS 50 E1 (92%) E1 ’1. OPMB 9% t—BuLi, ZnMe2 ' 8' \ + H F O ~78°C : PMBO \ TMS then aldehyde 58 B o 58 M ”0““. no '0 3551? Hi-i 50 (41%) 28 importantly, with the amphidinolide A subunits, aldehyde 58 and zincate 8 this experimental procedure was stereoselective with only the desired diastereomer 60 being isolated albeit in modest yields (41%). One explanation for the low yield, as compared with the model study, is that aldehyde 58 is unstable in the presence of zinc Lewis acids. Therefore, MgBrgoEtzo was again studied as the chelating metal. It was found that magnesium bromide etherate is not soluble in 3210 alone but often dissolved in EtZO/benzene solutions. The successful coupling procedure was repeated using MgBrzoEtzo in an Et20/benzene solution (9:1) for the zinc Lewis acid. In this coupling procedure the crude TLC was promising, although the precomplexed aldehyde solidified upon cooling the reaction mixture. Indeed the desired addition product was isolated as a single diastereomer but in a lower yield (20%). Although the yield was low, the reaction was promising since MQBFQOEIQO could be used in the stereoselective chelation controlled addition. Efforts to improve the yield via a mixed metal reaction were conducted as illustrated in Scheme 33. Prechelating aldehyde 58 with MgBrzoEtgo and using the zincate derivative of B as the nucleophile afforded alcohol 60 (34% yield) and a diastereomerically pure by-product (11% yield) alcohol 61. The by-product was the result of the transfer of methyl instead of Scheme 33. Optimization of Chelation Addition Et Et OPMB 9%51 51+ 0 .‘ 0’ H t-BULI. 20MB: -7s°c _ PMBO then aldehyde A3 as MgBrz-Etzo (~- oomplex H0“ O 58 . Br W a TMS 29 tn fragment B onto aldehyde 58. It should be noted that the above observation is surprising, since it has been shown that the methyl group has the least aptitude in transferring from a zincate species.37 Furthermore, if two groups have the same aptitude in transferring then the larger of the two will typically transfer to relieve steric congestion. With the formation of by-product 61 under the zincate nucleophilic addition conditions, optimization of the coupling reaction using only magnesium was attempted. A stock solution [1.0 M EtZO/PhH (3:1)] of MQBI’QOEtzo was prepared, which facilitates the addition of the magnesium salt. Secondly, CH2CI2 was added to the aldehyde solution to increase solubility. Finally the flash column was deactivated with EtaN (1%) to prevent any acid promoted decomposition. With the above changes yields of 50 — 60% for the coupling were obtained. 30 B. Hydrostannylation of Skipped Enyne and Subsequent Cross-Coupling With the successful stereoselective synthesis of the AB fragment, the hydrostannylation of skipped enynes was investigated. This would be important for the planned Stille cross-coupling to form the Ca - C4 bond. We were particularly interested in the regiochemistry of such hydrostannylation because with conjugated enynes it is known that the regiochemical outcomes are different under palladium and free radical mediated reactions i.e. the internal isomer predominates under palladium conditions and the E-isomer under free radical conditions. In the preparation of the enyne substrates (Scheme 34), the trimethylsilyl moiety of the protected alkynes had to be removed. In earlier attempts, this deprotection was incomplete and low yielding under K2C03/MeOH Scheme 34. Investigation into the Deprotection of TMS-alkynes OH OH OH K2C03 \ TMS \ H T 50 52 (19%) M. major product (2) THF HFopyridine THF . . or recovered starting material (82%) (3) Citric Acid MeOH TBAF/HOAc , 62 (4) THF ”90%) conditions but quantitative under basic fluoride (TBAF) conditions. Unfortunately, the deprotection did not scale-up well. When the deprotection was run on a 0.5 mmol scale or greater, the TBAF solution proved too basic leading to the formation of the allene product (eq. 2 , Scheme 34). Allene formation could be 31 minimized if the reaction was carried out at 0 °C, albeit with low to moderate yields of the desired alcohol. Since deprotection under basic conditions was unsuccessful, acidic conditions were tried. First a citric acid/MeOH protocol was used. Although the citric acid / MeOH protocol is known to cleave silyloxy ethers, the procedure gave none of the desired product. Only starting material (eq. 3, Scheme 34) was recovered. Even with more traditional acidic conditions (HFopyridine/T HF), deprotection did not occur. Fortunately, it was found that an acetic acid buffered TBAF solution39 could be used (eq. 4, Scheme 34) for 50 and similar substrates (>90% yield). We then began to explore the hydrostannylation reaction of skipped enynes. No reaction underfree radical condtions was observed. We postulate that the lack of stannane Scheme 35. Pd-Mediated Hydrostannylation formation could result from Bu3SnF 0” OH . . . _____.R°d'3" / s e the formation of a stabilized ‘2 (PhaP)2PdCI2 Snsu. * " ”3 TBAF(oat.) E-isomer 63 internal isomer radical at the doubly allylic (12:1) methylene position. Hydrostannylation of skipped enyne 62 (Scheme 35), under palladium catalysis was nonregioselectivity (1 .2:1 E- to internal isomer). Therefore, attempts were made to convert skipped enyne 50 to the 1-bromo-alkyne derivative which under palladium catalysis are known to give predominately the E-isomer.40 When TMS-alkyne 50 was subjected to the Scheme 36. Attmpted Bromo-alkyne Synthesis OH OH NBS TMS Bf 50 32 bromo-silicon exchange reaction (Scheme 36) several products were formed none of which was the desired compound. If the Stille reaction is to be the last bond connection in the total synthesis of amphidinolide A, the poor regioselectivity in the palladium mediated hydrostannylation would mean that half of our material would be lost. Therefore, other hydrometallation reactions were investigated i.e. hydrozirconation and hydroboration. Both of these metallated species can be used directly or derivatized for cross-coupling. Hydrozirconation of TMS-alkynes is known to occur with the desired regioselectivity.41 In terms of diene construction, the newly formed zirconocene Scheme 37. PMB Protection of Model Skipped Enyne OH OPMB PMB \ _—_—. WW V\/‘\H/\~ms protection \ TMS so 04 (12 - 55%)‘ a Conditions A: pCHaoPhCHpC(NH)CCl3, TfOH (0.3 mol%), EIZO, 42 hours, (12%) Conditions 8: p-CH3OPhCHZOC(NH)CCI3, TfOH (0.3 moI°/o)/CSA,cycIohexane/CH2CI2, 44 hours, (55%) Conditions 0: p-CH3OPhCH200(NH)CCI3, CSA (10 mol%), cyclohexane/CHZClz, 24 hours, (45%) Conditions D: p-CHsoPhCHZOC(NH)CCl3, CSA (10 mol%), cyclohexane/CHZCI2, 40°C. 12 hours. (51%) Conditions E: NaH, PMBCI, 3 hours, several try-products. no desired protection could be used directly or converted to the vinyl stannane species for the cross coupling reaction. In our hydrozirconation investigation, we found that the alcohol of skipped enyne 50 had to be protected. The protective group of choice was the PMB group. As illustrated in Scheme 37, the protection was unsuccessful under basic conditions (NaH, PMBCI) leading only to formation of several by-products. Fortunately, protection under acidic conditions (PMB-trichIoroacetimidate, catalytic acid) gave moderate yields of the PMB ether after optimization. Although literature recommends the use of triiflic acid (0.3 33 moI%) as the acid catalyst, in our system it was found that CSA gave better yields and in shorter reaction times. Attempts at the hydrozirconation of skipped enyne 50 included a subsequent in situ transmetallation42 to the vinyl stannane (Scheme 38). Isolation of the vinyl stannane and subsequent protiodesilylation would allow us Scheme 38. Attempted Hydrozirconation of TMS-alkynes (I) OH OH R 1. szerCl / recovered starting \\ 7”: SnBua material R 2. BuasnOMe 5°R=TMS R=TMSorH 62 R = H to verify the success of the reaction by spectroscopic comparison with an authentic sample formed by hydrostannylation/protiodestannylation of the parent alkyne. Unfortunately, attempts at this sequence failed and only starting material was recovered. Therefore, the TMS moiety was removed, and the hydrozirconation reaction was repeated with skipped enyne 62. Unfortunately, the results were the same as before. It is known that acidic protons can be incompatible with such reaction conditions.41b Thus, the alcohol hydrogen could be contributing to the reaction’s failure. Therefore, the PMB-protected alcohol Scheme 39. Attempted Hydrozirconation of TMS-alkynes (ll) OPMB OPMB TMS 1. Cp22rI-ICI / recovered starting m ”/1: Wswua mate“. TMS 2. BU3SI'IOM6 (89%) 64 OPMB OPMB Fl m 1. Cp22rHCI ¥/> / D R 2. 020 64R=TMS R=TMSorH 65 R = H 34 series was investigated (Scheme 39). When the reaction was repeated with skipped enyne 64, the same results were obtained, recovered starting material (89%). With this failure we began to consider if the doubly activated methylene hydrogens were again problematic. To explore this, the hydrozirconation reaction was repeated with both skipped enynes 64 and 65 and quenched DZO. Deuterium incorporation at either the doubly activated methylene position of 64 or at the acetylenic position of 65, would suggest an incompatibility between skipped enyne and the relatively basic Swartz reagent. Experimentally several products were isolated; however, none of them was the result of a simple deprotonation then deuteration. With the lack of success with the hydrozirconation reaction, skipped enyne 65 was subjected to hydroboration conditions with catecholborane (Scheme 40). The hydroboration of 65 was unsuccessful affording only recovered starting Scheme 40. Attempted Hydroboration of Skipped Enyne 65 OPMB OPMB / recovered starting \ catecholboraneif/l¢ Bloalz material \ (54%) enyne (54%). Since neither the hydrozirconation nor the hydroboration of skipped enynes could be realized, the palladium mediated hydrostannylation protocol was reinvestigated in efforts to improve the regioselectivity. Although the palladium mediated procedure was inefficient, it was used in preparing the E-vinyl stannane, that was needed for the Ca — C4 bond cross coupling investigations. Our initial cross coupling investigation began with model vinyl stannane 66 as a mixture of regioisomers. The inseparable mixture of 35 regioisomers was used in a subsequent Stille reaction since precedant suggests that E-vinyl stannanes react preferably over internal stannanes in cross coupling Scheme 41. Stille Cross-coupling of Model System BuasnF PM o 8 Red- SiI OPMB \ (Ph3PI2PdCI2 SnBu + internal \ cat TB AF 3 isomer 65 (crude) O O 0E1 0E1 (MeCN)2PdCI2 OPMB as + I ——> / / / DMF 12 hours 49 67 reactions. This proved true in our case (Scheme 41). This successful albeit low yielding Stille reaction between vinyl stannane 66 and B-iodo ester 49 was “proof of principle” for the proposed mode of diene construction. In a total synthesis, a model study is only beneficial if the “real” system parallels the model system in reactivity and compatibility. In our early model investigations, the trimethylsilyl moiety of the skipped enynes had to be deprotected with an acetic acid buffered TBAF solution to prevent the presumed methylene deprotonation. Accordingly, skipped enyne 60 was deprotected with the TBAF/HOAc protocol (> 98% yield, crude) to give terminal enyne 68 (Scheme 42). BU3SI'IH was introduced across the triple bond of alkyne 68 under the palladium protocol utilizing our anhydrous in situ method (BuasnF, TBAF, Red- Scheme 42. Pd-mediated Hydrostannylation of Enyne 68 E1 E1 3+0 I" BussnF Red-Sil TBAF/HOAC (PhaP)2PdCIz internal (930/0. CNdO) W isomer (64%, 2 steps) \ H (1.5:1, Efint) 36 Sil) of Buaan generation (vide infra) to give a separable mixture of regioisomers. With E-vinyl stannane 69 in hand the “real” cross-coupling question could be addressed (Scheme 43). With the sluggishness of the Stille reaction utilizing (CHacN)2PdCI2 as the palladium catalyst in our model study, a more reactive catalyst system was sought. The catalyst system of choice was the combination of szdbaa and AsPha in NMP. The Stille reaction between vinyl stannane 69 and vinyl iodide 49 using the above conditions gave the desired diene 70, fragment ABD, in 50% yield. Although the Stille reaction gave a moderate yield, heat (50 °C) and long reaction times were needed (16 hours). Scheme 43. Synthesis of Fragment ABD E1 Conditions A: szdbaa, AsPha, NMP, 50 °C, 16 hours. 50% yield. Conditions 8: CuTc, NMP, room temp.. 30 min, 56% yield. Liebeskind43 has developed a copper mediated cross coupling protocol, which substitutes stoichiometric quantities of the inexpensive and air stable copper (I) thiophene-2-carboxylate (CuTc) for the Pd(0) catalyst. The Liebeskind procedure is often carried out at ambient temperatures but can occur at 0 °C and dramatically shorter reactions times are often possible i.e only minutes instead of hours. In our system (Scheme 43), the cross coupling reaction between vinyl stannane 69 and vinyl iodide 49 with CuTc as the “catalyst” was indeed quicker (30 minutes, room temperature) and slightly better yielding (56%). To test the scope of the cross-coupling reactions a more elaborate vinyl iodide ester was 37 investigated, and it was found to be similar in all regards to the previous cases under both the Stille and Liebskind protocols (Figure 3). Although the hydrostannylation/Stille 7, reaction sequence was successful, the Figure 3' Diene ABCD regioselectivity of the hydrostannylation of skipped enynes still needed improvement. In particular, we wanted to reinvestigate the formation of 1-bromo- alkynes, and the subsequent palladium mediated hydrostannylation. In our earlier model investigation we found it necessary to protect the alcohol of the enyne as a PMB ether in order to prevent side reactions during certain hydrometallation reactions. As such (Scheme 44), the reinvestigation into the formation of the 1-bromo-alkyne series began with the protection of alcohol 60 as PMB ether 72 under the optimized acidic conditions. The TMS moiety of the protected skipped enyne 72 was deprotected under standard TBAF/HOAc Scheme 44. PMB Protection of Fragment AB E1 "” 7% JL HJCO PMBO 60 > CSA (cat) 9.- cyclohexane / CH2CI2, 40°C PMBO (41%) R TBAF/ 72 R = TMS HOAc 73 R = H (93%, crude) E1 57° I,“ 8113311 I'I (PhaPthCI2 THF + BUaSflSRBUg Sn803 38 conditions to give the desired alkyne 73 (93% yield, crude). Upon exposure to AgNOa and NBS in acetone 1-bromo-alkyne 74 was isolated (90% yield, crude). Instead of using our in situ method for the generation of Buaan, stock Buaan was initially used for the hydrostannylation reaction. This proved problematic as the BU3SHH was added too fast, resulting in the Pd(0) mediated formation of hexabutyltin dimer. Purification and product ratio determination was difficult since the reaction was run on a very small scale (37 mg, 0.062 mmol). However, while the hydrostannylation reaction was not synthetically useful, it was again “proof of principle” that the bromo-silicon exchange is a viable reaction. This would pave the way for future experiments (see page 56). C. Hydrolysis of Advanced Intermediates In our retrosynthetic analysis, we envisioned a Yamaguchi macrolactonization as a potential method for forming the 20-membered macrocycle. For this macrolactonization to be realized, the ethyl ester of advanced intermediate 70 would have to be hydrolyzed. The hydrolysis of ethyl ester 70 would serve two purposes. First, it would properly fuctionalize the ABD fragment for potential Scheme 45. Hydrolysis of ABD Ester 70 esterification with a BC 51 57° ’1,’ fragment. Secondly, we hoped LiOH 4 several products THF/MeOH/H20 (3:1:1) that the carboxylic acid would be a crystalline product and that an X-ray structure could be obtained. The X-ray structure would allow us to unambiguously assign the stereochemistry at 08, which was established during 39 the earlier chelation coupling. Unfortunately, all attempts at the above mentioned hydrolysis (LiOH, THF/MBOH/H20) were unsuccessful (Scheme 45). Although TLC analysis suggested the ester was hydrolyzed, the parent acid was not isolated. This result is significant since it suggested that for a successful approach to the natural product either the ester bond linkage between fragments C and D must be formed before the C3 - C4 bond formation or the current Ca — 0., bond cross-coupling connection must occur with the parent B-iodo acid instead of the ethyl ester. In regards to the latter approach, all attempts at a Stille cross- coupling between vinyl stannane 85 and B-iodo acid 42 were unsuccessful. Therefore, in our revised retrosynthetic analysis of amphidinolide A, the former approach was pursued. In earlier investigations, the alcohol of advanced intermediate 60 could only be protected as the PMB ether under acidic conditions (PMB trichloroacetimidate, catalytic CSA). The yield of the reaction was poor to moderate, and often contaminated with residual imidate and/or the corresponding amide. All efforts to optimize the protection, such as using cyclohexane freshly distilled from CaHg and recrystallized CSA were not overty beneficial. The reaction was slightly cleaner, Scheme 46. TBS Protection of Fragment AB but the yield was still only at 87° 1,,- moderate (50%) at best. The A or B decision to protect the alcohol as a PMB ether was chosen Conditions A: TBSOTf. i-PerEt, 0% yield. simply because at the and Conditions B: TBSOTf, 2.6-lut., 95% yield. 40 game an exhaustive DDQ deprotection could be used to obtain the desired tetrol. However given the difficulties above, a different protection strategy was investigated. The alcohol was protected as a silyl ether (Scheme 46). Interestingly, the protection of alcohol 60 with TBSOTf and r'-Pr2NEt as the base yielded none of the desired product. Instead, addition of a saturated aqueous solution of NH4C| turned the reaction solution black and a solid formed after the addition of 820. With no apparent explanation for this phenomenon, the reaction was repeated with 2,6-lutidine instead of i-PerEt, giving advanced intermediate 76. The yield of this protection consistently ranged from 90% to quantitative. With a high yielding protocol for the protection of the advanced AB subunit, attention was directed toward derivatizing the hydrophilic segment. After hydrolysis of the isopentylidene acetal, we planned to protect the newly formed diol as the p-methoxybenzylidene acetal. A selective reductive opening of the acetal would liberate the parent diol with the secondary alcohol protected as a PMB ether. Upon oxidation of the primary alcohol, the second chelation Scheme 47. Acetal Hydrolysis of Fragment AB Derivatives E1 57% ,4. HO,” PMBO PTSA PMBO + + on MeOH 90“". Teso““' TMS 77 73 (1)72 R = PMB - - - (2) 76 R = TBS 6% 23% 17% (3) so R = H . 49% 17% (4) 76 R 3 TBS CSA. CH2Cl2/MeOH - 46% 25% see experimental section for detail procedures. 41 controlled vinyl addition could be investigated. As such (Scheme 47), p-toluenesulfonic acid monohydrate (PTSA)44 was initially studied as the acid catalyst for acetal hydrolysis of several AB fragment derivatives. First isopentylidene 72 (eq. 1, Scheme 47) was hydrolyzed at room temperature over 14 hours. Although the desired product was not isolated, the reaction was very informative, since it suggested that the hydrolysis was slow. Indeed, slow hydrolysis of the isopentylidene acetal was further demostrated when acetal 76 was hydrolyzed (eq. 2, Scheme 47). Deprotection of the TBS-silyl ether was competitive with hydrolysis of the acetal as indicated by the products isolated: desired diol 77 (6% yield), triol 78 (23% yield) via loss of TBS moiety, and alcohol 60 (17%) via loss of TBS moiety only. Since TBS-silyl ether 76 was very labile under the acidic conditions, hydrolysis of the parent isopentylidene acetal was investigated (eq. 3, Scheme 47). When the hydrolysis of isopentylidene acetal 60 was tested on a small scale, it was found that heat was needed to drive the reaction to completion. Hydrolysis of isopentylidene acetal 60 on a preparative scale afforded several products: desired trioI 78 (49% yield), recovered acetal 60 (17%) and two minor products as indicated in Figure 4. In efforts to increase the yield and selectivity, alternative a reaction conditions were studied. The Eth acid catalyst was changed from PTSA to CSA, and the solvent system from me 79 MeOH to a MeOH/CHzClz solution. In Figure 4. Acetal Hydrolysis By-products addition, all reactions employing CSA 42 were run at ~ 40 °C. Hydrolysis of acetal 76 (eq. 4, Scheme 47) with the above conditions afforded triol 78 (46%) and alcohol 60 (25%) via loss of TBS moiety. The products formed under these conditions (no diol) show that the TBS-silyl ether is more labile to protic acidic conditions than the acetal. Other methods for the removal of acetals, which are more compatible with TBS-silyl others were investigated at a later time (see page 44). Continuing with the functionalization of the advanced AB fragment (Scheme 48), triol 78 was protected with the dimethyl acetal of p-anisaldehyde to give a diastereomeric mixture of p-methoxybenzylidene acetal 81 (78% yield). In turn, the secondary alcohol was protected with TBSOTf (53% yield) to give silyl ether 82, which is the substrate needed for investigation of the reductive opening of the benzylidene acetal. Towards this end, benzylidene acetal 82 was subjected to DIBAL-H conditions, which are known to give the desired regioselectivity. Unfortunately, the reaction yielded a regiochemical mixture of Scheme 48. Functionalization of AB triol 78 PMP 0” 99MB "“3 PTSA ‘ >~o OPMB ms HO ’ // ' o 5 / . prC5H4CH(OMe)2 / 5H DMF 6e 78 (78%) TBSOTf E ’1 R g H (53%) 82 n - TBS OPMB QPMB / TMS OH OPMB / TMS 82 M. HOW + (meow (50%) 6133 fires 83. (1:1) 631: mono-protected alcohols 83a/83b (50% yield), as well as, a polar by-product that suggests the loss of a TBS moiety. Reductive opening of benzylidene acetals are also directed by heteroatoms,45 in particular oxygen. Therefore, in our case 43 the PMB ether of 82 could serve as a chelating site for DIBAL-H and thus direct the undesired ring opening of the acetal as well as assisting in the deprotection of the TBS-silyl ether. With the apparent lack of selectivity in the reductive ring opening of benzylidene acetal 82 and poor chemoselectivity in the hydrolysis of the isopentylidene acetal of advanced AB intermediates, we decided the hydrolysis of the isopentylidene acetal would have to occur earlier in the synthesis. Hence, a QUICK investigation into the Scheme 49. Hydrolysis of Early Intermediates acetal hydrolysis of earlier a e . . +0 FeCIa-Si02 no reaction intermediates was undertaken. °M°Et ‘—or—* Dowex H“ 19° Borrowing from our earlier ' ' CSA OH results, conditions that are 19 MGOWCHzc'z Ho ca . . 40 °C, 6 hrs / reported compatible With TBS-silyl ethers were explored initially, but to no avail. One such reagent was ferric chloride supported on silica gel,“ which is easily prepared from FeCl3-6HZO and silica gel. When isopentylidene acetal 19 (Scheme 49) was subjected to the FeCI3-Si02 reagent in CHCI3, no reaction occurred even after prolonged stirring (~15 hours) at room temperature. Obviously, the reaction conditions were too mild. Subjecting acetal 19 to stronger conditions such as Dowex H+ resin also resulted in recovered starting material. Since TBS-silyl compatible hydrolysis conditions were not successful, acetal 19 was subjected to CSA conditions in a solution of MeOH/CH20I2. These conditions afforded the hydrolysis product within six hours. Furthermore, application of the above 44 Scheme 50. Hydrolysis of Acetal 54 to give Diol 84 Et Et *0 gPMe OH gPMe OH 99MB 0 5 SP” CSA H20 (”0380' (”033.0 r sph MeOH/CH2CI2 imidazole (65%) NaH, DMSO —'———> 84 ma or roduct 85 PMBCI, THF ( j p ) conditions to a synthetically useful intermediate was also successful (Scheme 50). The hydrolysis of isopentylidene 54 afforded the desired diol 84 (64%), along with recovered starting material (9%) and a small amount of a triol presumably via deprotection of the PMB ether. When the reaction was carried out with a small amount of water, the completion time was shortened, and the yield of desired diol 84 increased to 80%. The selective protection of diol 84 would give an appropriate functionalized “semi-symmetrical" molecule (Figure 5) and would increase our flexibility in the total OPMBQPMB synthesis of amphidinolide A. Toward this end R° : 3"" (Scheme 50), the primary alcohol of diol 84 was Figure 5, Semi-symmetrical Intermediate selectivity protected to afford the tripropylsilyl ether 85 (65%) along with the diprotected derivative 86 (22%). Unfortunately, all attempts at protecting the secondary alcohol as a PMB other were unsuccessful. The major product of the attempts was parent diol 84, indicating hydrolysis of the tripropylsilyl ether under the protection conditions. In later investigations, a successful protection protocol was realized when the initial protection was as the triisopropyl silyl ether (see page 48). 45 In addition to the couplings previously discussed, one other attempted coupling gave valuable information for the design of our new approach. In studies by Joe Ward and myself, it was determined that a metallated fragment B denvatlve could not serve as a nucleophilic Scheme 51' Attempted source in the displacement of halides and/or Fragment 3 Displacement TsO tosylates (Scheme 51). Therefore, a k [1: M Me \ displacement coupling between fragments B and \n/\TMS or ’/ M = Mng, LI. CU Ph/VBr C to form the C16 — C17 bond would not be isobwz'mmide possible. In summary, although the first generation approach did not lead to the total synthesis of amphidinolide A, much valuable information was gained that assisted in the design of our second and third generation approaches to the natural product. 46 Chapter 3. 2"cl Generation Approach - Application of RCM The successful construction of the subunits in our first generation approach allowed for the investigation of multiple coupling strategies and provided valuable information as to which coupling sequence would be employed in our second-generation approach. Our second retrosynthetic breakdown of amphidinolide A (Scheme 52) affords three fragments D - F. Key steps for the final elaboration included a Stille cross-coupling, chelation controlled addition, Scheme 52. 2"GI Generation Retrosynthetic Analysis Ring-closing p metathesis WW0; =:sterifioation Chelation Stille Coupling controlled addition Amphid'inolide A indium allylation, Mitsunobu esterification, and ring-closing metathesis (RCM). Application of the RCM reaction is the underlying theme of our second generation approach. The RCM reaction is a powerful synthetic tool for the construction of carbon-carbon double bonds. Moreover, with the advent of well- defined metal ruthenium centered carbene catalysts developed by Grubbs, the RCM reaction has served as a key step in the total synthesis of several natural products. With regards to the total synthesis of amphidinolide A, several questions concerning chemo- and stereoselectivity of the ROM must be addressed. In terms of chemoselectivity, there exists the potential for the metathesis to occur at several different olefins, which poses two questions: Could 47 we limit metathesis to the two mono-substituted olefins? Secondly, can we minimize dimerization and favor versus ring closure? In terms of stereoselectivity, could we control the geometry of the newly formed olefin? The above questions and others that emerged in our investigations were answered through the total synthesis of several analogs of amphidinolide A. A. Synthesis of “Z”-amphidinolide A The transition from our first to second generation approach was relatively easy due to flexibility in our initial design. An RCM precursor corresponding to the left hemisphere of amphidinolide is readily prepared from isopentylidene acetal 54, an intermediate in our original synthesis of fragment A. The synthesis Scheme 53. Selective Protective Group Functionalization of Diol 84 . OH 99118 TIPSCI OH 99113 messy reaction Jfl. HOVHrK/SH‘ Min—'9. Tlpso vk[r?\/SP11 several products DYridlne cat. DMAP 0 °C 24 hours 84 87 DDQ I 40 sieves PMP /l\o + o>\o OH Ho\/I\"j\/sph \/I\”/i\/sph 88 88a of RCM precursor E (Scheme 53) began with hydrolysis (CSA, MeOH/CHzClz, 40 °C) of the acetal 54 to give diol 84. At this stage, two approaches were investigated to differentiate the two alcohols: (1) selective protection of the primary alcohol as either an alkyl ester or silyl ether and (2) selective protection of the secondary alcohol via PMB acetal formation with the neighboring PMB ether. When diol 84 was subjected to the DDQ oxidative conditions in the absence of water,“7 the desired p-methoxyphenyl 1,3-dioxane 88 was formed but 48 the corresponding p-methoxyphenyl 1,3-dioxolane 88a was also formed presumably via migration of the acetal moiety. Without the ability to control the regioselectivity during the acetal formation, efforts were directed toward the selective protection of the primary alcohol. Attempted protection of the primary alcohol with pivaloyl chloride gave several unindentifable products.48 Reaction of diol 84 with TIPSCI, imidazole and catalytic DMAP gave the desired mono- protected diol 87 in excellent yields (91%). With an efficient protocol to differentiate the primary alcohol, protection of the remaining secondary alcohol was studied (Scheme 54). The TIPS-silyl ether was chosen for the 1° alcohol due to its known resistance to basic hydrolysis. However, under standard basic conditions (eq. 1, Scheme 54) (NaH, DMSO/T HF) for PMB-ether formation, the TIPS-silyl ether in alcohol 87 was partially hydrolyzed. The desired fully protected triol 89 was isolated in moderate yields (57%) along with recovered Scheme 54. PMB Protective Investigation of 2° alcohol 87 OPMB QPMB TIPSO ’ SPh . recovered + and + alcohol as 34 e7 NaH. PMBCI (57%) (10%) (8%) (1) DMSO/THF (1 :3) NaHMDS PMBCI 87 ' = 70° - - THF, TBAI (eat) (5 l) (2) NaHMDS. PMBCI : (79%) - - (3) THF/DMSO (3:1) alcohol 87 (8%) and the deprotected diol derivative 84 (10%). When the reaction was repeated in the absence of DMSO and with NaHMDS as the base (eq. 2, Scheme 54), the reaction was sluggish. However, the reaction went to 49 completion upon the addition of catalytic TBAI and heating albeit in a modest yield (57%). The optimized reaction protocol (eq. 3, Scheme 54) consists of deprotonating the alcohol with NaHMDS and subsequent addition of DMSO and PMBCI to give the fully protected triol 89 in excellent yields (79%). lntennediate 89 is a pseudo-symmetrical molecule in the sense that both ends are masked aldehyde equivalents and with routine transformations either end can participate in the chelation controlled nucleophilic addition reactions (Scheme 55). Initially, the TIPS-silyl ether was deprotected with TBAF (84%) to give alcohol 90. Oxidation of alcohol 90 with Dess-Martin periodinane in the presence of pyridine gave aldehyde 91 in excellent yields (97%). Unfortunately, Scheme 55. Vinyl Magnesium Bromide Addition (I) OPMBQPMB T F OPMBQPMB TIPSO , Sph 1. BA (54%) H : sp,, MsBrz-Et20 several 2. Doss-Martin from, products oxidation (97%) 0 39 91 aldehyde 91 proved to be incompatible with the chelation controlled nucleophilic addition. Upon addition of MgBrgoEtzo to the aldehyde, the reaction solution tumed black. Analysis of the crude material by 1H NMR showed no indication of the desired product. The sulfide, which is only six atoms away from the aldehyde and thus capable of intramolecular nucleophilic addition,49 is possibly causing the poor reaction. To overcome this, the phenyl sulfide was converted into the corresponding aldehyde (Scheme 56). Oxidation of sulfide 89 with m-CPBA and subsequent Pummerer rearrangement (T FAA, Ac20, 2,6-lutidine) of crude sulfoxide 92 gave oi-acetoxy sulfide 93 (65% yield, 2 steps). Reduction of oi-acetoxy sulfide 93 with 50 Scheme 56. Conversion of Phenyl Sulfide 89 to Aldehyde 95 OPMBQPMB OPMB QPMB 1. m-CPBA t npso SPh 1.LiEthH(82%) : TIPSO _ H 89 2. TFAA, Ac20 2. Doss-Martin (o) 2,6-Iutldine OAc (91 /o) O (60%, 2 steps) 93 95 Super-hydride” gave alcohol 94 (82%), and with subsequent oxidation under Dess-Martin conditions, aldehyde 95 was isolated (91%). With the isolation of aldehyde 95, the first of two chelation-controlled additions was investigated. Addition of vinyl magnesium bromide to aldehyde 95 (Scheme 57) was inconsistent. Depending on the Grignard source, a substantial amount of alcohol 94, presumably via 1 electron reduction, was isolated. Indeed Scheme 57. Vinyl Magnesium Bromide Addition (II) OPMB 99% (8:1) \ OPMB gPMe TIPSO ’ OH * 96 ‘—__MgBr2-Et20 aldehyde MgBrzoEtzo / 3 OT'PS ”M98! 95 %MDBI 94 (1.1) dark solution tan solution OH 96 (60%) (70%) the Grignard solution proved to be the cause of this phenomenon, because with careful observation it was found that the dark black commercial solutions of vinyl magnesium bromide gave considerable reduced product while the clear tan transparent commercial solutions gave desired alcohol 96 diastereoselectively (8:1) in average yields of 70%. The TIPS-silyl ether of 97 was deprotected with TBAF (94%) to give alcohol 98 (Scheme 58), which was oxidized with Dess- Martin periodinane (92%) to give aldehyde 99. The addition of the Grignard of fragment 8 under chelation conditions occurred with poor diastereoselectivity (1:1). Unfortunately, alcohol 100 was isolated as a diastereomeric mixture due to poor separation via flash chromatography. After deprotection (T BAF/HOAc, 98% yield, crude) of the TMS-acetylene to give terminal alkyne 101, application of our 51 Scheme 58. Preparation of E-vinyl stannane 102 OPMB gPMe OPMB OPMB NaHMDS, PMBCIt / - o‘nps TBAF - OH Doss-Martin THF/DMSO (3:1) (94%) IO] (790/0) PMB PMB (920/0) 97 as OPMB OPMB OPMB gPMB BuasnF PMBCI», / r H MgBrz-EtzO _ Red-Sil ' ' -—-—> ““9 \ (Pth)2PdCI2 PMBO OPMB 0 mm cat. TBAF 99 (55%) (41%. 2 steps) 110“" SnBu3 TBAF/ 102 HON: 100 n = TMS 98% crude 101 R = H novel siloxane reduction of organotin halides and subsequent in situ hydrostannylation methodology gave RCM precursor vinyl stannane 102 as a regio-mixture (41% yield over 2 steps, E / internal 1.2:1). The left and right RCM precursors, vinyl stannane 102 and (2)-vinyl iodide 300,50 were connected via a Stille cross-coupling reaction to give diene 103 (Scheme 59). Although the vinyl Scheme 59. Cross-coupling of vinyl stannane 102 and (2)-vinyl iodide 300 szdbaa AsPha NMP, 50 °c (24%) 102 stannane employed in the Stille reaction was a mixture of E- and internal stannanes, only the E-isomer reacted. With the isolation of diene 103, the ring- closing metathesis reaction was investigated (Scheme 60). The reaction was attempted under dilute conditions to minimize dimerization. Initially, a room temperature benzene solution of diene 103 was allowed to stir for 24 hours in the presence of the first generation Grubb’s catalyst, (CyaP)2Cl2Ru=Ph. As indicated 52 by 1H NMR, no apparent reaction occurred. The reaction was repeated several times in benzene-(d5) with and without heating (60 °C) but to no avail. There was no reaction even after 2 days of Scheme 60. Attempted ROM (|) heating. One potential problem CIA FINE”: Ph oi\‘ " a’(CYIzi “G rubb's catalyst“ for the lack of reactivity is that no reaction the catalyst is rendered inactive through coordination to one of several hetero-atoms in diene 103. It has been shown that the addition of Ti(i-PrO)4 can break up inactive chelates and thus facilitate ring-closing metathesis. However, the addition of Ti(i-PrO)4 was not beneficial in our RCM reaction. Another potential reason for the lack of reactivity is sterics. Hoye has shown that allylic alcohols increase the rate of reactivity of RCM reactions in comparison to the corresponding allylic alkoxy ether. Thus, an RCM precursor with a deprotected allylic alcohol was needed. Synthesis of such a precursor began with intermediate 100 (Scheme 61). After protecting the alcohol as Scheme 61. Preparation of RCM acyclic diene 107 OPMB gPMe TMS OPMB gpMe Br TBSOTf = // _.A9"03 = // 10° ——*. . / . NBS / . 2,6-Iutldine E. 900/ de : OPMB ores I °' C'“ I OPMB OTBS (72%) 1 04 105 Bu3SnF OPMB QPMB fl. ? \ $118113 fl. (Ph3P)2PdCI2 / _:_ yinvl cat, TBAF OPMB 6755 Wide (57%. over 2 steps) 106 30° (49%) DDQ several products CHZCIZ I H20 53 TBS-ether 104, it was noticed that the substrate was clearly a mixture of diastereomers. Although the substrate was a mixture, the material was carried fonivard. TrimethylsilyI-alkyne 104 was converted to 1-bromo-alkyne 105 upon exposure to AgNOa and NBS (90%, crude). Once again, application of our novel siloxane reduction of organotin halides and subsequent in situ hydrostannylation methodology gave E-vinyl stannane 106 in a 57% yield over 2 steps. Instead of using a Stille protocol for the cross-coupling reaction, the Liebeskind copper (I) thiophene-2-carboxylate (CuTc) methodology was utilized. The copper mediated cross-coupling between stannane 106 and (2)-vinyl iodide 30050 gave the RCM diene 107 in a moderate yield (49%). As stated earlier, the more favorable unprotected allylic oxygen moiety was needed to test our sterics hypothesis and probe Hoye’s acceleration observation. Thus, we attempted to deprotect the PMB-ethers. While exposure of diene 107 to the DDQ oxidation protocol lead to removal of the PMB moieties, as evident by the R) change, none of the several products isolated were the desired triol. With the need for an allylic alcohol in the ROM substrate and the lack of success in deprotecting acyclic diene 107, the synthesis of the left half of the ROM substrate clearly required a different protection strategy. Toward this end, the Scheme 62. Preparation of Alcohol 109 synthesis of the new RCM diene Ho omegmaonps pm. pm omegmaonps ridine began with alcohol 94 (Scheme 62). 94 7%) 106 OPMBOPMB Since a TBS-silyl ether is needed TBAF mo 5 0H (96% yield, from 94) later in our synthetic pathway, 109 54 protective group manipulation of the primary alcohols was examined. Protection of the free alcohol with pivaloyl chloride gave fully protected tetra-oi 108 in a 74% yield. Subsequent deprotection of the TIPS-silyl other with TBAF gave alcohol 109. In this sequence of reactions, it was found that subjection of the crude pivaloyl ester to the TBAF deprotection conditions gave the desired alcohol in better yields (96% yield over 2 steps). At this stage of our synthetic venture, it was apparent that multi-gram quantities of advanced intermediates would be needed. Thus a shorter high yielding route to intermediate 109 was sought. As illustrated in Scheme 63, D-arabitol was chosen as the starting chiral sugar and through desymmerization via protective group manipulation, gram quantities of alcohol 109 were prepared. Scheme 63. Preparation of Alcohol 109 via D-arabitol E1 MeO OMe E1 Et 81 OH 9H X EI 51 1 . Sanpyridine E1 E1 M 5' Et 0 9 DMSO- I'P'zNE‘ . o ‘0 ———‘ r ‘ o % 2. Ph3P=CH2 ' OH OH OH PTSA, DMF D bit I 40 °C (90%.Zsteps) -ara ° (quantitative) 111 113 ~11 OH 911 OH 9H CSA : ‘TIPSCI TIPSO : OTIPS PMBO ccr, MeOH, 40 °C imidazole ——.CSA (cat ) H H DMAP, DMF (33%) 114 (97%) 115 OPMBQPMB TB F OPMBQPMB . OPMBQPMB TIPSO ’ OTIPS ._A_. Ho ’ OH flQL, PivO ’ OH (>950/o) pyridine (41%) 116 118 109 D-arabitol was protected as bisisopentylidene acetal 111 in high yields. Oxidation of the 2° alcohol with SOgopyridine and DMSO gave ketone 112 in 68% yield. Wittig olefination with Ph3P=CH2 installed the olefin in near quantitative yields affording acetal 113. Hydrolysis of the acetal with CSA in MeOH provided 55 tetra-0| 114 quantitatively, which was then selectively disilylated at the primary alcohols with TIPSCI to give diprotected tetrol 115 (77% yield) along with the mono-protected derivative (20%). Both secondary alcohols were protected as the PMB-ether under acidic conditions to give fully protected tetrol 1 16 (38% yield) and the mono-protected PMB derivative 117 (37%). The removal of the TIPS-silyl ethers with TBAF provided the corresponding diol 118. Selective mono-protection of the diol with pivaloyl chloride provided the target alcohol 109 in 41% yield along with di-pivaloyl derivative (24%). Although some of the yields Scheme 64. Vinyl Magnesium Bromide Addition (III) OPMBQPMB 109 M. PM) . H [—W‘"... several products [0] MgBrg-Etzo (quant.) O 110 for the desired compounds are at best moderate, mosit side products formed were easily converted to the target alcohol 109. Returning to the synthesis of the amphidinolide A analog (Scheme 64), the oxidation of alcohol 109 with Doss-Martin periodinane in the presence of pyridine was uneventful and gave aldehyde 110 in a 98% yield. Aldehyde 110, like similar aldehydes in our earlier approach, is pseudo-symmetrical and therefore Scheme 65. Preparation of Aldehyde 122 OPMB OPMB OPMB gPMe / TMS TBSOTf PNOMH M08r2.E120 > pr W ”“9 a (30%) o m OH TMS 110 (55%) 119 OPMB gPMe / TMS omegms / ms WOW Su r. ride 8W i THFO°C i re 12°OTBS (88%) o s 121 n = CH20H (88%) WP I: 122 n = cuo (>95%) the addition of vinyl magnesium bromide or the Grignard of fragment B could be reversed. The addition of the latter proved to be the most rewarding. With the addition of vinyl magnesium bromide, several products were isolated and none of which were the desired alcohol. Addition of fragment B under chelation condition gave only one diastereomer of alcohol 119 in a 55% yield (Scheme 65). The resultant alcohol was protected as a TBS-silyl ether 120 (TBSOTf, i-PerEt, 80% yield). With the successful protection of the secondary alcohol, the Piv protected 1° alcohol was deprotected with Super-hydride” (88% yield) to give alcohol 121. Scheme 66. Preparation of (E)-vinyl Stannane 125 CH PMBCI,“ / BU3$HF MgBrz'Etzo - . Aldehyde122 ———> Red Sil ”Miler PMBO (PhaP)2PdCIg cat. TBAF (60%) TBSO\\‘ ‘ (73%) R AgNOa, NBS 123 R = we (92%) 124 n = Br 125 Oxidation of the alcohol with Doss-Martin periodinane gave aldehyde 122 (98% yield). With the isolation of aldehyde 122, the second chelation controlled nucleophilic addition was carried oUt. Contrary to the earlier vinyl magnesium bromide addition, the coupling (Scheme 66) of the aldehyde and vinyl Grignard gave the desired alcohol 123 with good diastereoselectivity (7:1) (60% yield). In preparation for the hydrostannylation reaction, the trimethylsilyl alkyne was converted to 1-bromo-alkyne 124 (92% yield). The preparation of 1-bromo- alkyne warrants a brief comment. During the formation of 1-bromo-alkyne 124 (Scheme 67) a C-12 silylated by-product (124a) was often formed in 25% - 50% yield. Fortunately, exposure of TMS-silyl ether 124a to citric acid in MeOH 57 Scheme 67. Recycling of 1—bromo-alkyne by-product Citric Acid (10 sq), MeOH r 10 minutes I (>95°/o) 123 124 124. allowed for the selective deprotection of the TMS-ether in the presence of the TBS-ether to give the desired alcohol 124 in excellent yields (>95%). The 1-bromo-alkyne was hydrostannylated to give the (E)-vinyl stannane 125 in excellent yields (73%) (Scheme 66). If the crude 1-bromo-alkyne was used in the subsequent hydrostannylation reaction, the vinyl stannane was isolated in an average yield of 50% over the 2 steps. As illustrated in Scheme 68, (E)-vinyl Scheme 68. Cross-coupling of Vinyl Stannane 125 and (2)-vinyl Iodide 300 126 stannane 125 was coupled with the ROM substrate right half, (2)-vinyl iodide 300,50 via the Liebeskind cross-coupling protocol to give diene 126 in 60% yield. With the isolation of a sterically less demanding RCM diene substrate, our hypothesis about the steric demands in the RCM reaction was tested. 58 When a solution of diene 126 (Scheme 69) in CH20I2 (0.005 M) at room temperature was combined with 15 mol% of Grubb’s catalyst added dropwise (~ 22 minutes), no reaction was detected by 1H NMR after 24 hours. When the reaction was repeated Scheme 69. Attempted RCM of Diene 126 - o e WIth 50 ”'0' A Of th Grubb's catalyst (15 mole%) . = no reaction 0112ch (0.005 M) catalyst and a diene room temperature 24 hours Diene 126 concentration of 0.001 Gmbb.s cams, (50 mole%) S'OW addition : ‘H NMR and Mass Spec. indicates M in refluxing CHgClz, “2053:2113 '°""" Poss'b'e macrocycle reaction finally occurred. Two identifiable products were isolated, one of which had the correct molecular ion peak as indicated by high resolution mass spectrometry and the appropriate 1H NMR signals. The 1H NMR spectrum of the second isolated compound was not clean and the mass spectrum did not correspond to the starting diene, desired macrocycle, or dimer. The mass balance of the two isolated products (1 :1 ratio) accounted for 67% of the correct mass balance. After extensive experimentation, a reaction procedure was established (Scheme 70), which consisted of the dropwise addition (~4 — 6 hours) of Grubbs’ catalyst (50 mol %) to a refluxing CHzclz (0.001 M) solution of diene 126 and continuation of stirring for a total of 24 hours. This procedure resulted in the isolation of the desired macrocycle 127 in a 47% yield along with a by-product in a 14% yield. The by-product was not the dimer as initially thought but truncated ketone 128. Besides the presence of ketone 128, the reaction was highly chemoselective with respect to which olefins participated in the metathesis. Only the mono-substituted olefins reacted with no sign of 59 Scheme 70. Preparation of (2)-macrocycle 127 via RCM PICYI3 ph (”MA _/ Ci' I u 910103 (50 mol%) CH20|2 (0.001 M) 40 °C, 24 hour A ketone 7 47°/ ( °) + (14%) .. (20 mol%) ‘ CH2C|2 (0.001 M) ' 40 °C, 10 hour (88%) dimerization. Moreover, only the E-olefin was formed. In retrospect, formation of ketone 128 is not surprising given Hoye’s observations on the use of allylic alcohols in ROM reactions. He found that if the rate of RCM was not fast, then this truncating pathway competed with cyclization. This competing pathway was eliminated with the use of the more active second generation Grubb’s catalyst. With the use of the N-heterocyclic carbene catalyst (Scheme 70) not only was the desired macrocycle isolated in a higher yield (88%) but the amount of catalyst (20 mol%) and time for the cyclization (10 hours) was substantially reduced. At this point in our synthetic venture, all that was needed to complete the synthesis of the Z-isomer analog of amphidinolide A was removal of the protective groups. Given the poor results of our earlier deprotection efforts, a model system was investigated in order to find optimal conditions for the Scheme 71. PMB Deprotection Investigation (I) OPMB QPMB TMS 0“ 2” / “‘3 W DDQ i / . / / ; Cchlzlt—BuOI-I/pHfl buffer ; OH 5113s (55%) “/0 ores 123 130 R a C(O)PMP 6O deprotection of the PMB-ethers. As such (Scheme 71), exposure of PMB-ether 123 to DDQ in a CH20I2/ t-BuOH / pH=7 phosphate buffer solution (5:1 :1) gave the undesired p-methoxyphenyl ester 130 as a regioisomer mixture. Ester formation proceeds through the intramolecular capture of a benzyl carbocation by the neighboring alcohol and subsequent opening of the newly formed benzylidene acetal by DDQ oxidation and hydrolysis. To alleviate this problem, alcohol 123 was protected as a TBS-silyl ether 131 (82% yield) as outlined in Scheme 72. Although the deprotection of 131 was initially quite frustrating, it was a helpful learning experience. In that, even successful results do not always occur as expected. Careful observation is always needed. For instance, we thought that the removal of the PMB residues would lead to a more polar Scheme 72. PMB Deprotection Investigation (II) OPMB gpMe TMS 0” 2” / TMS ? // DDQ = / ‘ / / ; CHZClzlf-BuOI-t/pHfl buffer é OR OTBS ((55; 2)) OTBS OTBS ° 132 TBSOTf 123 R g H 2.6-Iut. (82%) 131 R = TBS product. However, deprotection of the PMB ethers gave a dioI with an Rf very close to that of the parent compound. This led me to initially believe that no reaction had occurred. However upon more careful analysis, we learned that the deprotection was a success, allowing isolation of the desired diol 132 in 59% yield. This successful protection-deprotection strategy was applied to the macrocycle analog as illustrated in Scheme 73. Protection of Z-macrocycle 127 as TBS-silyl ether 133 was substantially slower (12 hours) than the acyclic model system, but the yield remained 61 consistently high (>90 %) as long as the reaction was cooled (0 °C) during the initial addition of 2,6-Iutidine and TBSOTf. With the isolation of 133, the all important PMB deprotection step was investigated. Similar to the model system, Scheme 73. Synthesis of the (2)-amphidinolide A analog TBAFOHOAC ——————> THF, rt. 24 hrs (33%) 1135011 (92%) ‘27 R " H' R = PMB 133 n =TBS, 11': PMB poo (52%) 134 n = res, 11': H the yield of diol 134 was only moderate (52%), and relatively small differences in R1 were observed. The final step in the total synthesis of the fully deprotected Z-analog of amphidinolide A was the removal of the TBS-silyl ethers. This was accomplished with an acetic acid buffered TBAF solution in THF, giving Z-amphidinolide analog 135 in 33% yield. 62 B. Total Synthesis of the Assigned Structure of Amphidinolide A The divergent point toward the synthesis of amphidinolide A began with the cross coupling of vinyl stannane 125 with (E)-vinyl iodide 30150 (Scheme 74). Liebeskind cross coupling protocol between vinyl stannane 125 and (E)-vinyl iodide 30150 provided diene 136 in a moderate 49% yield. Attempts to increase the cross-coupling yield were to no avail. Interestingly and in contrast to the 2- Scheme 74. Cross-coupling of Vinyl Stannane 125 and (E)-vinyl Iodide 301 analog, reaction with the (E)-vinyl iodide was very slow at 0 °C and thus had to be carried out at room temperature. Equally, interesting is our use of excess vinyl iodide (2 - 4 equivalents). Liebeskind has shown that the CuTC reagent is efficient in promoting the homo-coupling of vinyl iodides.51 In our system the presence of the homo-coupled product is not evident until the vinyl stannane is completely consumed. Following the preparation and isolation of diene 136, the all-important RCM reaction was investigated (Scheme 75). Initially, the first generation Grubbs’ catalyst was used with the optimized conditions from the Z-analog sequence. Unlike the Z-isomer, diene 136 under the RCM conditions only afforded truncated ketone 137 and recovered starting diene. With a notion that the conformational predisposition of the starting diene may affect the rate of ring closure, the reaction was repeated in refluxing benzene with hopes that the 63 Scheme 75. RCM of Diene 136 to Give Truncated Ketone PICYIII Ph 0 0"".Au— PMBO,, Ci’ " IL(0)03 (50 mol%) PMBO 0112012 (0.001 M) ’ 40 °C, 24 hours (34%) Tsso“"' 1 37 increased temperature and change in solvent may influence and/or change the conformation of the diene and thus promote the cyclization. Unfortunately, the change in solvent had no affect on the RCM reactions as the 1H NMR of crude reaction mixture showed only the ketone and starting diene. The change in olefin geometry between the Z- and E-acyclic dienes could essentially have two effects: (1) moving the end olefins farther apart (2) affording a new conformation which allows for internal chelates. Both of these outcomes would disfavor cyclization of the E-isomer. With hopes that the second hypothesis was operative, the reaction was repeated with the addition of Ti(i-PrO)4 to hopefully break up any chelates and promote cyclization. Unfortunately, 1H NMR of the crude residue was identical to all previous cases; only ketone and starting diene. Besides by the addition of additives, formation of the truncated ketone could possibly be suppressed by protecting the allylic alcohol. Such a protection could 3'30 provide insight into the Scheme 76. TMS protection of RCM diene exact timing of the 1,3-hydrogen shift and reductive elimination in 11161111135 31*; Hoye’s mechanism for ketone - conditions: (a) TMSOTf, 2,6-Iutidine: (70% yield) format'on- (o) AcCI, pyridine; (0% yield) 64 The protective group must be relatively small in order to avoid steric problems; therefore, the alcohol was protected as the TMS-silyl ether as illustrated in Scheme 76. Unfortunately, exposure of diene 138 to the ROM conditions (Scheme 77) only resulted in dimerization as evident by both 1H NMR and HRMS. Presumably the newly introduced steric demands prohibited metathesis from occurring at the olefin nearest the allylic oxygen. Instead the mono-substituted olefin of the skipped diene reacted in an intermolecular manner Scheme 77. Dimerization of Diene 138 via RCM PICyia (50 mol%) 01-1201) (0.001 M) 40 °C, 19 hours (79%) with itself. This result further substantiates Hoye's theory concerning the acceleration of the ROM reaction with the use of allylic alcohols.51 Clearly, the initial metathesis does not occur at the olefin nearest the allylic oxygen moiety with the use of the less Lewis basic and sterically more crowded silyl ether. Still aiming to exploit the rate acceleration of the ROM reaction by allylic oxygen functionality, protection 'of the allylic alcohol with a more Lewis basic (and better coordinating) protecting groups (i.e. aceto) were attempted. Unfortunately, Scheme 78. RCM of Diene 136 to give (E)-macrocycle 140 CH 012012 (0.001 M) 40 °C. 24 hours 0 (35%) 1380““ 65 all efforts at installing the acetate group failed. With the lack of success with the first generation Grubbs’ catalyst in the RCM of both diene 136 and 138, the more reactive second generation catalyst was explored. RCM with the second generation N-heterocyclic carbene catalyst afforded macrocycle 140 in only 35% yield along with several unidentifiable products (Scheme 78).53 Several modifications to the reaction procedure were investigated in attempts to increase the yield of macrocyclization. As part of these efforts, the reaction medium was changed to refluxing benzene. Unfortunately, the elevated temperature did not have a substantial effect on the yield of the reaction or the products produced. Hoveyda has developed a modified second M m “\N ‘Mes generation catalyst, where the cyclohexyl %_Ie°l I ‘CI phosphine ligand is replaced with the tethered d isopropyl styrene moiety (Figure 6)-54 With his Figure 6. Hoveyda's Catalyst catalyst the reactivity is retained and the initial metathesis has even been initiated at room temperature. More importantly, his catalyst is inherently more stable, presumbly due to the styrene ether tether. This enhanced stability should theoretically allow one to maintain good reactivity with less catalyst since decomposition is minimized. Decreased catalyst loads should also give a cleaner reaction i.e. less ruthenium decomposition products and hopefully facilitate identification of the by-products. Our initial RCM investigation with Hoveyda’s catalyst began by repeating the optimized procedure for the second generation Grubb’s catalyst. Unfortunately, reaction in either CH2CI2 or benzene still gave several products in low yield. The reaction was repeated at room 66 temperature with hopes that the lower temperature would disfavor the unproductive pathways. Unfortunately, at room temperature the initial metathesis was very sluggish, and decomposition of the starting diene was evident after 2 days. Although the more reactive N-heterocyclic carbene catalysts allowed for some cyclization with diene 136, exposure of TMS-protected diene 138 resulted only in dimerization, suggesting that the steric demands were overriding the enhanced reactivity of the catalyst. The difference in reactivity between the E- and Z-dienes is very significant for understanding the mechanism of the ROM reaction and how subtle changes can affect both the reactivity and selectivity of the reaction. Currently, there is a debate in the literature as to the extent that the predisposition of the starting diene conformation influences the efficiency of ring-closure.55 The results in our study clearly show that the conformation of the starting diene does indeed Scheme 79. Synthesis of the Proposed Structure of Amphidinolide A TBAFoHOAc ——> THF, rt, 24 hrs (25%) 141 R:TBS,R'=PMB 142 R=TBS,R'=H TBSOTf(92°/11)E"‘o F1 3 H. R :- PMB DDQ (29%) matter. Despite our inability to improve the RCM, the protocol could provide us sufficient material needed to complete the synthesis. Thus application of the earlier protection-deprotection strategy was studied. As illustrated in Scheme 79, the alcohol of macrocycle 140 was protected with TBSOTf in the presence of 2,6-lutidine to give the fully protected 67 macrocycle 141. DDQ oxidative deprotection led to the isolation of diol 142 albeit in low yield (29%). The TBS-Silyl ethers were deprotected with a TBAF-HOAc solution to give 1, the proposed structure of amphidinolide A. Disappointingly 1H NMR data of the synthesized material do not completely correlate to Kobayashi’s 1H NMR data on the natural product. The structural assignment of our compound would appear sound since all chemical transformations used are all well established, but more importantly the assigned structures of all intermediates were fully supported spectroscopically. In some 166 Figure 7. Possible Structure of Amphidinolide A (or its enantiomer) cases, advanced one- and two-dimensional NMR techniques were used to absolutely secure the assigned structures. Careful examination of Kobayashi’s data, revealed no direct correlation between the relative chirality of the left and right halves of the molecule. Therefore, if the relative stereochemistry within each half is correct, one of the halves of the natural product could actually be the antipode of Kobayashi’s assigned structure. Toward this end, the total synthesis of epimer166 (Figure 7) was carried out. If Kobayashi’s relative stereochemistry for each half is correct but how the correlation is incorrect, then epimer166 would be the natural product or its enantiomer. 68 C. Total synthesis of an Epimer of Amphidinolide A via L-arabitol Compound 166 was targeted since the antipode of the left hemisphere is easily accessed by simply changing the starting chiral sugar. As illustrated in Scheme 80, L-arabitol was protected as bisisopentylidene acetal 143 in high yields albeit as a regio-mixture. The ratio of the acetals greatly depended on controlling the reaction temperature. Oxidation of alcohol 143 with SOs-pyridine and DMSO gave ketone 144 in 68% yield, which was readily separated from the aldehydic by-product.°° Wittig olefination with Ph3P=CH2 installed the exo-olefin in excellent yields to give bisisopentylidene acetal 145. Hydrolysis of the acetal with CSA in MeOH provided tetra-0| 146 quantitatively, which was selectively disilylated at the primary alcohols with TIPSCI to give diprotected tetra-0| 147 (68% yield, 2 steps) along with the mono-protected derivative 148 (22% yield, 2 steps). Both secondary alcohols were protected as the PMB-ether under acidic Scheme 80. Preparation of RCM substrate via L-arabitol (I) Moo X01111 Et Et 9” 0“ Et Et 1- 303° Et Et M DMSO, i-Prn:NEt ‘ 0 o '- o PTSA}, DMF 2 PhaP=CH2 0” 0“ 0” (56%. 2 steps) L-arabitol 145 NH gri OH 9H CH JL __C_3_§L__, : .T'PSC' TIPSO ’ OTIPS ””30 00': MeOH. 40 °c Imidazole —-——’CSA (can) OH OH DMAP. DMF “8%) 146 (68% yield, 2 steps) 147 gpMeopMe QPMBOPMB , QPM9°PMB TIPSO ’ OTIPS 181':- HO ’ OH % PivO i H (>95%) pyndlne (52%) 149 150 153 conditions to give fully protected tetra-0| 149 (48% yield). Removal of the TIPS- silyl ethers with TBAF provided the corresponding diol 150. Selective mono- 69 protection of the diol with pivaloyl chloride provided the target alcohol 153 (52% yield). The previously prepared mono-protected TIPS tetra-0| (148) is readily converted to the target alcohol through a similar but modified protection strategy. The remaining primary alcohol is selectively protected as the pivaloyl ester (81% yield) to give diprotected tetra-0| 151, where the primary alcohols are differentiated. Protection of the two remaining secondary alcohols as the PMB- ethers (PMB-trichloroacetimidate, CSA, 81% yield) provided fully protected tetra-ol 152, which upon deprotection of the TIPS-silyl other with TBAF (75% yield) provided target alcohol 153. With the above sequence of reactions, gram quantities of alcohol 153 can be prepared. Dess-Martin oxidation of alcohol 153 in the presence of pyridine gave aldehyde 154 (>98% yield) which was set up for the first of two chelation controlled additions. Addition of the Grignard of fragment 8 (Scheme 81) occurred with complete diastereoselectively giving alcohol 155. The resultant alcohol was protected as a TBS-silyl other (156) (TBSOTf, i-PerEt, 76% yield). Primary alcohol 157 was liberated after Super- Hydride® reduction of the ester (THF, 0 °C, 91% yield). Oxidation of the alcohol Scheme 81. Preparation of ROM substrate via L-arabitol (II) QPMB OPMB QPMB PMB TMS TBSOTf PNOMH M93r21E120 t MW fiPerE‘ erMp (76°/ 0 m 0) TM 154 (55%) S 155 gmeoma / ms 9911909119 / ms PIVO ' / SuEr-Mride R ' / THFO°C 15601139 ores 157 n = CH20H (88%) WP I: 159 n . c110 (93%) with the Dess-Martin periodinane in the presence of pyridine gave aldehyde 158 (98% yield) setting the stage for the second chelation controlled addition. Similar to the D-arabitol series, the addition of vinyl magnesium bromide (Scheme 82) occurred with only good diastereoselectivity (8:1 ratio) and in modest yields (56% Scheme 82. Preparation of ROM substrate via L-arabitol (III) BuasnF Red-Sil ——> (PthdeCIz cat. TBAF MgBQ-Etzo Aldehyde 158 %Mgfir (56%) (72%) R AgNOa, NBS 159 R a TMS (78%) 160 R .. Br 161 yield). In preparation for the hydrostannylation reaction, TMS-alkyne 159 was converted to 1-bromo-alkyne 160 upon exposure to NBS and catalytic AgNOa (78% yield). The hydrostannylation of 160 utilizing our in situ Buaan protocol afforded (E)-vinyl stannane 161 in a 72% yield. As illustrated in Scheme 83, the copper mediated cross-coupling between vinyl stannane 161 and (E)-vinyl iodide 30150 provided RCM diene 162 in 63% yield. When diene 162 (Scheme 83) was subjected to our optimized RCM conditions, the desired macrocycle 163 was isolated in only 27% yield along with an unidentifiable by-product. To complete the total synthesis of amphidinolide A Scheme 83. Preparation of Diene 162 and Subsequent RCM PICYI3 P11 OH ' 01/, I = “2:33;” PMBO 0:13074 PMBO + CUTC PMBCI,” (50 mol%) A mac/h, ' NMP ' VII'IYI CHchz (0.001 M) . ' 49°/ T880 T880 '33:” ( °) 0 40 °C, 24 hours 0 O 162 (35 k) 183 71 isomer 166, the protection-deprotection strategy was again utilized. As such (Scheme 84), the alcohol of macrocycle 163 was protected as TBS-silyl ether 164 (82% yield). DDQ oxidative deprotection led to the isolation of diol 165 albeit in poor yields (43%). After removal of the TBS-silyl ethers with a TBAF-HOAc solution, isomer 166 was isolated. Unfortunately, there were still inconsistencies between the 1H NMRs of our synthetic material and the natural product. This result combined with our previous result suggest that the relative stereochemical assignments maybe in error. Scheme 84. Synthesis of 166, an Isomer of Amphidinolide A TBAFoHOAc ——. THF. rt. 24 hrs (33%) 154 RSTBSJR'SPMB 155 RBTBSJR'IH TBSOTf (82%) E 163 R = H. R = PMB DDQ (43%) 72 Chapter 4. 3'“ Generation Approach - Application of Alder-ene Reaction As with the second generation approach, the flexibility of our original retrosynthetic design allowed us to simultaneously explore a third generation approach to the natural product. Our third retrosynthetic breakdown of amphidinolide A affords three fragments D, G, and H. The planned syntheses of these fragments paralleled the syntheses of the 2'“1| generation subunits. The major difference between the second and third generation approaches is how the top 012 - 016 skipped diene moiety will be installed. In this approach, we Scheme 85. 3rd Generation Retrosynthetic Analysis Alder-one WW 2...... How (I Chelationk Stille Coupling controlled addition Amphidinolide A envisaged Trost’s recently developed ruthenium mediated Alder-ene reaction, as the key step. This reaction could occur either intramolecularly (cycloisomerization) or intermolecularly (cross-coupling). We intended to investigate both approaches. 73 In preparation for the AIder-ene reaction, the known ruthenium catalyst was prepared as outlined in Scheme 86. The catalyst was obtained as a yellow solid in an overall yield of 49% from RuCla. Scheme 86. Preparation of the Alder-ene Ruthenium Catalyst FluCl3 1’Whexadi°"°= [(“ceHII’RUC'zlz “(05%) [CPFlu(u-CeHa)lC' NH4PF0 [CpRu(n-CGH5)]PF3 _h_V.. [[CPRU(CH30N)3]PF0 Synthesis of fragment G began with aldehyde 110 (Scheme 87). Chelation controlled allylation of aldehyde 110 with tributylallylstannane gave alcohol 167 with excellent diastereoselectivity (>99z1) and moderate yields (68%). The newly generated alcohol was protected with TBSOTf to give TBS- silyl ether 168 in excellent yields (91%). Alcohol 169 was liberated upon exposure of the pivaloyl ester to a Super-Hydride“ reduction (T HF, 0 °C, 90% yield). Oxidation of the alcohol with the Dess-Martin periodinane in the presence of pyridine provided aldehyde 170 (88% yield). Addition of the Grignard of Scheme 87. Preparation of Alder-ene Vinyl Stannane 174 PMB QPMBH PMB QPMB PMB QPMB : \/\ ._- PivO . Sn8u3 OPlv TBSOTf \ . OPiv (91%) ores 1 68 (68°/ ) MB gmao me QPMB Super hydride Dess-Ma___rt_i_.n \ ? H McBrzoEtzo THF 0 °c pyridine Bng (90%) ores"5 (83%) ores o \fl/\ms 1 70 (53%) moo”, BuasnF. Red-Sil PM” (Ph3P)2PdCl2 ‘ PM TBAF (2 drops) ’ .- R0“ 1 (54%) TBSO“ 20:1 174 18301: 171 n = H (80%) 172 R 8 T83 74 fragment B to aldehyde 170 under chelation control occurred with excellent diastereoselectivity to give alcohol 171. After protection of the resultant alcohol as a TBS-silyl other (172) (TBSOTf, 2,6-lutidine, 80% yield), it was noticed that the product existed as a 20:1 mixture of diastereomers, presumably at C-8. As before preparation for the upcoming hydrostannylation (Scheme 87), began by conversion of the TMS-alkyne to a 1-bromo alkyne (173) (66% yield). The prerequisite for the subsequent cross-coupling reaction, (E)-vinyl stannane (174), was generated with our in situ Buaan hydrostannylation protocol (64% yield). Oddly enough, the cross coupling between vinyl stannane 174 and (E)-vinyl iodide 30250 proved quite challenging (Scheme 88). Leibeskind’s protocol, which consistently gave yields in the range of 50 — 60% with similar substrates, only afforded an unidentifiable by-product in low yield (<10%). Scheme 88. Cross-coupling of Vinyl Stannane 174 and (E)-vinyl Iodide 302 conditions: (a) CuTC. NMP; (0% yield) (b) szdba3, Ptha, NMP, so °c; (30% yield) Although diene 175 could be prepared via a Stille protocol, the yield (30%) was considerably lower than previous Stille reactions with similar substrates. With the synthesis and isolation of the intramolecular Alder-ene substrate, and the collection of several substrates for the intermolecular version, the ruthenium mediated reaction was investigated. After extensive experimentation with model compounds a procedure was established that gave a small amount of 75 Scheme 89. Ruthenium Mediatated Alder-ene Cross-coupling Investigation PMBCI,“ PMBO [CpFlu(Cl“l30l\l)3]PF://L> acetone \,. TBSO‘ OTBS 176 the desired product (~22% yield).57 As illustrated in Scheme 89, application of our model conditions to the intermolecular coupling of the amphidinolide A substrates did not provide any of the desired products. As indicated by TLC analysis, the reactions proceeded with very little consumption (<5%) of starting substrates. The lack of reactivity with alkenes 168 and 174 could potentially be explained through the coordination of the substrates via the PMB-ethers to the catalyst. The coordination of aromatic residues to the CpRu+ fragment has been shown to inhibit the activity of such catalysts. To eliminate the possibility of such binding, a substrate where the PMB moieties were removed was investigated. Unfortunately the vinyl stannane did not survive a DDQ deprotection of PMB- Scheme 90. Ruthenium Mediatated Alder-one Cycloisomerization Investigation [CpRu(CH3CN)3]PFo/l ‘ ,/ , acetone 76 ether 174. Furthermore, exposure of alkene 176 to the mthenium Alder-ene reaction also gave little or no reaction as indicated by TLC. The intramolecular investigations (Scheme 90) did not fair much better. Exposure of substrate 175 to the reaction conditions only resulted in recovered starting material. In all cases, prolonged stirring (24 hours) and/or increased catalyst loads did not affect the outcome of the reaction. Given these difficulties the Alder-one approach was abandoned. 77 Chapter 5. Indium Mediated Reactions Quite often a total synthesis project is accompanied with a synthetic methodology study. More importantly, the development of synthetic methods is often one of the reason for the synthetic venture itself. As such, the structure of amphidinolide A served as the basis for an alternative vinyl indium organometallic chelation controlled addition and would serve as a means of constructing the Ca and C12 bonds of our retro-analysis stereoselectively. In addition, the structure of amphidinolide A served as a scaffold for the invention of an indium mediated macrocyclization. A. Investigation of an Indium Mediated Macrocyclization Recently, there has been increased interest in the use of organoindium58 reagents for selective organic syntheses. Although the use of indium in organic synthesis has grown tremendously over the last several years, the scope of indium mediated reactions remains relatively limited. To our knowledge there is not yet an indium mediated cyclization protocol to form medium and/or large ring systems via a tandem di-allyl indium addition as that illustrated in Scheme 91. Allyl halides in the presence of indium Scheme 91. Indium Mediated Cyclization metal will add to both aldehydes$9 O m\¢;MM/m so W ° : Ho and alkynes. These results led us *1 '" ,, n>3 n>3 to investigate a tandem di-allyl indium addition to a substrate bearing an aldehyde and terminal alkyne. Formation of a medium-to-Iarge ring system via this method could serve as a model study for the construction of amphidindolide A. 78 The generation of allylic diindium species is both alkyl halide and solvent dependent.61 It has been shown that some di-haloalkenes react as if a geminal dianion was the reactive intermediate. In our case, the generation of such a dianion species would be detrimental since both nucleophilic additions would occur at the same allylic carbon resulting in a ring system with an undesired Scheme 92. Proposed Stepwise Indium Diallylation 0'an OH OH m\‘¢hM~/Br : RJW fl HWE 8r RCHO exo-olefin. To get addition at the C-1 and C-3 positions the desired cyclization must proceed in a stepwise fashion as illustrated in Scheme 92. Toward this end, a model study was investigated to probe such reactions. A retrosynthetic analysis (Scheme 93) of the model 20-membered lactone 181 gave rise to two fragments, vinyl iodide 177 and vinyl stannane 178. These two fragments would be joined via a Stille coupling and formation of the corresponding diene. Oxidation of the primary alcohol should give the acyclic substrate 180, which is a prerequisite for the indium mediated cyclization invesfigafion. Scheme 93. Retrosynthetic Analysis of Model Macrocycle O H BuSn a We“ 1 78 79 Vinyl iodide 177 was readily prepared by a 000 mediated esterification of the (Z)-B-iodo acid 48 and 5-hexyn-1-ol (Scheme 94) in a 70% yield. For the synthesis of the second Stille component a Zipper reaction‘32 of 3-octyn-1-ol gave Scheme 94. Synthesis of Model Vinyl Iodide 177 O OH 0 0% DCC ‘ + OH -——> \2/ ///\/\ (70%) '7; 48 177 \WVOH _____.KH /\/\/\/OH NH2(CH2)3NH2 // (53%) the required terminal alkyne in a modest yield of 55%. Due to difficulties with the employment of potassium hydride, including foaming during the formation of potassium 3-aminopropylamide (KAPA), an alternative Zipper procedure using sodium hydride63 was investigated. The NaH protocol was not as successful as the KH procedure as incomplete reaction with the former resulted in an inseparable mixture of terminal and internal alkynes. Scheme 95. Synthesis of Model Vinyl Stannane 178 \\ (Ph3P)2PdC|2 SnBua \/\/\/\OH Buaan 8"35" WON + MO” 173 tenninalzintemal (1:1) \ \W ——>A'BN 3‘53an + 17a 9180:. E:Z (4.7:1) With the isolation of 7-octyn-1-ol via the Zipper reaction, the desired vinyl stannane 178 was generated (Scheme 95). With the palladium mediated protocol, both the internal and terminal vinyl stannanes were isolated in a 1:1 80 ratio. Fortunately, free radical hydrostannylation, only afforded the terminal vinyl stannane 178 with an E:Z ratio of 4.7:1. With both subtargets for the model macrolactone in hand, their union was investigated (Scheme 96). Diene 179 was prepared by a Stille protocol in low yield. In reaction optimization experiments, it was found that the cross-coupling Scheme 96. Cross-coupling of Vinyl Stannane 177 and (2)-vinyl Iodide 178 °H.// o Bu38n WOH 'q 177 no reaction only recovered starting material 7 ‘73 Pdgdbaa. TFP THF / o o / ! ‘H/ o 0% eu33n Wm / "7 HO 6 / ‘ 173 = / (CH3CN)2PdCl2, DMF 179 (38%) / Sanpyn'dine O 01/ ————5 omso H 5 / mane: / (53%) 100 required reaction over 18 hours at room temperature. With regards to the palladium catalyst, it was found that the bis(acetonitrile)palladium (ll) dichloride catalyst was superior in the coupling reaction. Ironically, with tris(dibenzlideneacetone)dipalladium (Pdgdba) and tri-2-furylphosphine (T FP) as the catalyst system, only recovered starting material was isolated after 30 hours in refluxing THF. In any event, after subjecting the primary alcohol to the Doering-Parikh oxidation and obtaining aldehyde 180, the indium-mediated cyclization was ready to be investigated. 81 After examining the literature for allyl indium addition conditions to aldehydes and alkynes, our initial protocol for the cyclization reaction consisted of the following conditions64 (Scheme 97): THF as the solvent, indium powder as the indium source, and Nal for an in situ Finkelstein reaction. The reaction was Scheme 97. Indium Mediated Cyclization 180 181 stirred at room temperature for 6.5 hours until judged complete by TLC. After purification of the crude material by flash chromatography, two compounds were isolated. From 1H and 13C NMR both compounds were not of acceptable purity; therefore, further purification was attempted by preparatory HPLC. The amount of material recovered after preparatory HPLC was insufficient for complete spectroscopic identification. However, from the initial NMR data structures 181 and 182 are proposed. Compound 181 is the desired macrocycle, while alcohol 182 is proposed to be the result of an allylation of the aldehyde followed by protio-debromination. All efforts to optimize the reaction were unsuccessful, and therefore this approach to amphidinolide A was also abandoned. 8. Generation of Vinyl Indanes and Subsequent Addition In conjuction with the chelation controlled formation of the CrCa and 012-013 bonds, the generation and subsequent reaction of vinyl indium nucleophiles were investigated. Recent reports on the chelation-controlled 82 additions of allylindanes to carbonyls suggested that indium or ligated indium species may be useful in the chelation-controlled addition of vinyl species to carbonyls. Moreover, the generation of allyl and alkynyl indane species have been reported by several groups under varying conditions. Initially, we believed that the tin to indium transmetallation65 protocol would better serve our purpose. In preparation for the Scheme 98. Tin - Indium Transmetallation transmetallation reaction, me. 3 _ was" We” PhCHO eo33ncr several Vinyl stannanes m MeCN ’ no audit-on product . MCI; were Prepared Via the BUSSnWms PhCHO Buss“ 179 TMSCI no addition product hydrostannylation of the MeCN/THF parent alkyne. Vinyl stannane 178 was the initial stannane investigated. The progress of the reaction was monitored by the disappearance of starting material by TLC analysis. After 20 minutes of stirring at room temperature, stannane 178 was completely consumed and the distinguishable BuaanI TLC streak appeared. Unfortunately, direct spectroscopic identification of organoindanes is not yet possible. Therefore, the presumed formation of the vinyIindane is based solely on the apparent formation of Buaanl. After the addition of benzaldehyde, the reaction was allowed to stir at room temperature for an additional 60 minutes. Unfortunately, by 1H NMR the crude residue showed no signs of an addition product but rather destannylated alkene. Due to the acidic nature of hydroxy protons, an internal quenching process may be operative. Therefore, the protected silyl ether 179 was used in future reactions. Although the preferred 83 solvent for the transmetallation is acetonitrile, protected alcohol 179 was insoluble in acetonitrile, and therefore, a solvent mixture of acetonitrile and THF (3:1) was utilized. Also, the reaction was run under Barbier-type conditions, where the electrophile was present during formation of the organometallic. After stirring for one hour at room temperature, GC-MS analysis showed three peaks that corresponded to the mass of benzaldehyde, BuaanI, and destannylated alkene. The reaction was allowed to proceed at room temperature for a total of 4 hours, after which it was heated at 55 °C for 15 hours. The GC-MS analysis after heating was identical to the one after the initial hour. The reaction was quenched by the addition of trimethylsilyl chloride (T MSCI) with two goals in mind: (a) TMSCI could activate the carbonyl for nucleophilic addition and/or (b) the presumed vinyl anion would be trapped with TMSCI thus providing evidence of vinyl indium formation. GC-MS analysis after the addition of TMSCI no longer showed the peak corresponding to the destannylated alkene. In addition to the disappearance of the destannylated alkene peak two additional peaks appeared. Unfortunately, these peaks exhibited no readily recognizable molecular ion. The crude residue was purified by flash chromatography but the isolated products were unidentifiable by 1H NMR. The reaction was not a complete failure since it suggested that TMSCI or another Lewis acid could indeed initiate vinylindane formation. With that knowledge, the reaction was repeated with two equivalents of indium (Ill) chloride under the notion that the first equivalent would transmetallate with tin generating the vinyl indium species, and the second would serve to activate the carbonyl for nucleophilic addition. Unfortunately, the GC- MS analysis was identical to the previous reactions initially showing three peaks corresponding to the aldehyde, BuaanI, and the destannylated alkene. Collectively the results suggest that transmetallation from fin to indium is operative due to formation of BuaanI. Secondly, all the above reactions were stoichiometric in InCI3, and the formation of Buaanl was complete (100%) within 30 minutes. Therefore, although the reactions were a failure in effecting a nucleophilic addition, they suggested that a “vinyl indane” species was present but internally quenched. Under the following conditions: catalytic in indium, rigorously dried and distilled THF as the solvent, and no TMSCI, GC analysis after 1 hour and 16 hours were identical and showed the presence of Buaanl and destannylated alkene. More importantly, the starting vinyl stannane 179 was present, thus verifying the hypothesis of an internal quench by “wet” solvent or adventitious protons. Moreover, after the addition of TMSCI, which is knownssa'b to be needed for nucleophic additions with catalytic indium, the GC trace was again identical to all the previous cases where the reaction failed. These results are significant because they infer that the presumed “vinyl indane” species are stable over substantial periods of time but are not nucleophilic enough to add to carbonyl electrophiles. 85 Chapter 6. In Situ Generated Buaan and Subsequent Hydrostannylation In concert with our total synthesis, amphidinolide A has served as a scaffold for the invention of new synthetic methodology. The genesis of these studies lies in the Ca — C4 diene disconnection of our retrosynthetic analysis. The overall goal of our methods project was to develop a one-pot hydrostannylation /Sti|le reaction catalytic in both palladium and tin. Traditionally, the vinyl stannane is generated by either a palladium mediated or free radical hydrostannylation of the parent alkyne with Buaan. Although the use of Buaan in organic synthesis is widespread, there are several drawbacks with its direct use i.e. its cost and toxicity. While investigating different aspects of this project, I have focused on gaining a fuller understanding of applying siloxane reductions of tin halides for the generation of tin hydrides and subsequent in situ hydrostannylation of alkynes. Drawing on our experience with one-pot hydrostannylation/Stille couplings,66 we first focused on palladium-mediated hydrostannylations. We were initially disappointed when the reactions of several 1-alkynes with BuaanI, aqueous KF, and PMHS in THF proved inconsistent. Although the anticipated vinyltins were produced, yields and purity levels were usually low. However, after some experimentation, we found that using Et20 as the solvent and including a catalytic amount tetrabutylammoniun fluoride (T BAF) or iodide (TBAI)67 in the reaction, the expected vinylstannanes were formed in good yields and with standard regiochemical outcomes (Scheme 99; conditions A“). Importantly, potentially reactive groups such as alkyl halides or silyl ethers69 86 Scheme 99. In Situ Buaan and Subsequent Hydrostannylation (I) R R H __ ConditionsA Bu33n/\/ + _ or B Sn8u3 . internal isomer 5 ("‘3‘“) (minor) Conditions A: Conditions 8: Buaanl, PMHS, aq. KF, BugsnF, PMHS, cat. Bu4NF (or 8114M), cat. Bu4NF cat. (PhaP)2PdCI2, 5120 cat. (PhaP)2PdC12. £120 — yields alkyne product Conditions Conditions 8 H0 *8" 66% 67% HO re " Bu Snvm Eflnt. (24:1) Elint. (21:1) // Me 3 166mm 186mm 160 B 59% 67% : f-Bu Boaan" " E/Int.(>99:1) Elint.(>99:1) ‘ 61 139mm meanest: HO P11 HO Ph 8670 6870 M E/lnt. (12:1) E/Int. (>99:1) // Me 3°33" M° 11mm» 190.7190» 182 OH OH 72% 77% \\ 81:3an Elint.(1.4:1) Elint.(1.4:1) 3 191-11916 191mm: 3 183 \ ores ores 51%(n-2) 53%(n-3) Elint. (1:1) Efrnt. (1.3:1) V 3‘95" / n 1921111926 1961111966 184 (n=2) 185(n=3) or Cl 84% 78% W BUaSnN E/lnt.(1.4:1) E/rnt.(1.4:1) 2 2 194mm 194mm 186 62% 70% E/lnt. (17:1) Elint. (>99:1) Bu Sn \ 195mm 1WOGD // OH 3 H 187 remained intact throughout the reaction sequence. Furthermore, we observed no evidence of palladium-mediated hydrosilylation by the PMHS. Although the hydrostannylations with Buaanl/PMHS/KF(aq,) proved similar in many regards to those carried out with pre-made Buaan, there were several significant 87 differences. For example, palladium-catalyzed hydrostannylations using Bu3SnH directly are often complicated by the palladium-promoted conversion of Buaan into Bu38nSnBu3.7° Under the Buaanl/PHMS/KF(aq,) conditions, the vinylstannanes are accompanied by little if any hexabutylditin byproduct. Presumably, the rates of tin hydride formation and hydrostannylation are such that the relative concentration of tin hydride is always low, thereby minimizing dimer formation. This phenomena can be of particular practical advantage when vinyltins are desired in quantities that dissuade their distillation and when they are also sufficiently nonpolar so as to make the chromatographic separation from the ditin difficult. In terms of solvent, an obvious difference between our method and traditional hydrostannylations is the inclusion of water in the reaction. Although the advantages of running organic reactions in water have been well documented]1 we also recognized that a more anhydrous variant of our protocol would have its own advantages. Toward this aim, we examined the potential of KF or CsF in anh drous ether to serve as y Scheme 100. In Situ Buaan sources of fluoride for our reaction. Storchiometnc TBAF 1 eq. TBAF vinyl stannane + Unfortunately, under such conditions little H——: a MSW" PMHS; eu3snsneu, + (9'13?)sz unreacted alkyne . . . THF (1.5:1:1.5) or no Vinyltrns were generated. Given our observation that the biphasic reactions were facilitated by the presence of catalytic amounts of TBAF, we decided to explore its use in stoichiometric quantities. Employing 1 equivalent of TBAF did result in complete and rapid generation of Buaan; however, the subsequent hydrostannylation did not go to 88 completion, as the reaction afforded a 1:1 ratio of vinylstannane and unreacted alkyne, along with a 50% yield of hexabutylditin (Scheme 100). This result was not entirely unexpected as tetrabutylammonium salts are known to greatly activate the Sn-H bond, leading to hydrogen gas evolution and ditin formation.” The presence of BuasnSnBua and product were evidence that TBAF could serve to activate PMHS73 and thus generate Buaan; however, it was also clear that we would have to minimize the TBAF concentration if we wished for the tin hydride to be available for hydrostannylation versus dimer formation. However, treatment of terminal alkynes with Buaanl, PMHS, and catalytic TBAF in the absence of KF also failed to provide any vinylstannane. Presumably the TBAF is reacting with the BuaanI to form BuasnF and thereby not allowing for the activation of the PMHS." Assuming this were the case, we rationalized that by using pro-made BuasnF as the starting material the reaction could be made catalytic with respect to the TBAF, because a fluoride anion would be generated upon the PMHS-mediated conversion of BuasnF into Buaan. Indeed, this proved to be the case. As indicated in Scheme 99 (conditions 8), the catalytic TBAF/PMHS/BuasnF combination gave the desired hydrostannylation products in good yields and with no BuasnSnBua formation. Interestingly, the addition of aqueous KF to THF or Etzo mixtures of BuasnF and PMHS results in the formation of only trace amounts of stannane. Having applied the BuasnX/PMHS/F method of generating Buaan to in situ hydrostannylations via palladium catalysis, we next decided to investigate the performance of the method in the free radical hydrostannylations. We 89 believed the most significant difference between the palladium-mediated and free radical reactions would be the elevated temperatures under which the free radical hydrostannylations are usually conducted. Specifically, we were concerned that in refluxing benzene or toluene our fluoride source would react with the product stannanes, diminishing the overall yield and/or effectively quenching the reaction prematurely.75 These concerns proved to be unfounded. As illustrated in Scheme 101, both the catalytic TBAF/PMHS/Bu3SnF method and the KF/PMHS/Buaanl Scheme 101. In Situ Bu3$nH and Subsequent Hydrostannylation (ll) . N“ , Bu3$n n H : R CondrtionsC Buss" \ \ _, or D E ("‘31") Z (minor) Conditions C: Comm gD: BUsSnCI. PMHS. aq. KF. euasm-z PMHS, AIBN. cat. 364m, AIBN, PhHorPhMe.A Phi-l or PhMe,A yields alkyne product Concgtlons Conditions 0 0... 0H 62% 91% \ a SnN E/zran) E/Z(3:1) W “a / 3 1111-7191:: 191al191b 3 183 \ ores ores 60% 51% EIZ(4:1) E/Z(4:1) V WWW 19301936 193mm) 185 56% 63% E/Z(19:1) EIZ(77:1) 8 Sn \ 196671966 “smear: // H “3 H 187 OAC ON: 56% 69% \H 8%an EIZ(4:1) E/Z(4:1) 3 3 198M986 19M98b 196 Ms W 50% 53% \\ 3.,35nw 92m) 12mm) 3 3 199mm 199M996 197 90 performed quite well under free radical reactions. Again the chemical yields and regioselectivities76 observed in these reactions paralleled those found with the use of commercial tributyltin hydride. Unlike the palladium-catalyzed reactions, the employment of KF/PMHS/Buaanl under the free radical conditions did not require the inclusion of catalytic TBAF or TBAI. Presumably, the elevated temperatures of the free radical process allow the initial reaction between the KF, Buaanl, and the PMHS to take place at the water/benzene (or toluene) interface. The free radical reactions were similar to the palladium protocols in many regards, including the compatibility of silyl ethers with the procedure. At this point, we needed to address the PMHS-related phenomena, which occasionally complicates the workup of these reactions. Our standard workup usually involves a NaOH treatment, evaporation, and chromatographic purification. With base-sensitive substrates such as the acetate in Scheme 101, the caustic workup needs to be omitted to avoid partial saponification of the ester. In such cases, the NaOH wash can be eliminated from the workup, but when omitted an almost “plastic” substance will occasionally solidify upon evaporation Of the reaction solvent. Scheme 102. In Situ Buaan via Red-Sil This material is quite insoluble, /p Red-Sil, 8u38nF, _ /\/p and significant amounts of product // n "“°'°’°“’"3”)2P°°'2- ””33" \ n cat. TBAF. Et 0 13., (76%) 2 19:1 Efrntemal(195a/195t1) are usually trapped within the polymer. To avoid this periodic annoyance, we sought a low cost PMHS substitute that could be easily removed from the reaction mixture in an efficient and simple way. Surface-immobilized silyl hydrides on silica such as those 91 popularized by Fry et al.77 were viewed as excellent candidates for such a PMHS substitute. Reducing silica or “Red-Sil” is relatively simple to makem and when applied to palladium-mediated reductions77b can be easily removed by filtration of the reaction mixture. In our reactions, Red-Sil performed admirably (Scheme 102), although a 4-fold excess of silane was required. Importantly, the reactions are very clean, and simple filtration of the reaction mixture through a short pad of silica gel completely removed the silane, which did not contain any detectable amounts of vinylstannane, and simultaneously removed the other reaction salts. Again, no BussnSnBua byproduct was observed. We have also investigated the application of our new method to the in situ generation and reaction of other tin hydrides, especially trimethyltin hydride. The very high toxicity of trimethyltin hydride coupled with its volatility (59 °C at 760 mmHg)78 makes this reagent quite dangerous to handle. Ideally, this reagent is best prepared in situ, allowing its use without isolation. However, because of the absence of any commercially Scheme 103, In Situ M9330” available trimethyltin oxides, the 0H mm???“ 0H . . . . 3 1 mol% (Ph3P)2PdClz, 3 synthesrs of trimethyltin hydride has 183 cat.1('BAF.)5120 1,2:1E/intgma|(2oo./200b) 57% traditionally relied on the reaction of Red-Sil. \ 0“: M638nCl, aq. KF _ OAC strong hydride donors wrth V (man, (pnapyzpdcrzf “%Snxmg’ 1” 081- TBAF. E‘20 1.4:1 Efrntemal (201.1201 6) (62%) trimethyltin chloride.78a Given the substrate tolerance exhibited by our method, we believed the Meaanl/siloxane/fluoride combination would represent the best way to perform reactions with trimethyltin hydride.79 Indeed, trimethylvinylstannanes were 92 efficiently prepared via palladium-mediated hydrostannylations with trimethyltin hydride generated from the reaction of MeganI, KF (aq) and either PMHS or Red-Sil (Scheme 103). In summary, either BuaanIIPMHS/KF (aq) or the combination of tributyltin fluoride, PMHS, and catalytic quantities of tetrabutylammonium fluoride (TBAF) can serve as in situ sources of tributyltin hydride for both free radical and palladium-catalyzed hydrostannylation reactions. Furthermore, other trialkyltin halides such as trimethyltin chloride, as well as alternative reductants such as Red-Sil appear to be amenable to the method. 93 Conclusion: The convergent approach to amphidinolide A allowed for the construction of synthetically versatile building blocks. The synthesis of these building blocks and the flexibility in our design allowed for the simultaneous investigation of multiple coupling strategies, which gave valuable information as to which coupling sequence was used in our final approach to amphidinolide A. Our final approach allowed for the ready synthesis of amphidinolide A and unnatural analogs in 35 steps from articles of commerce with the longest linear sequence being 23 steps from L-(-)-ephedrine. The synthesis of amphidinolide A and unnatural analogs allowed for the instructional applications of organo-tin, indium, copper, palladium and ruthenium mediated reactions. In addition, the in situ Buaan methodology study, which had its genesis at the Ca - C4 bond of our retro-analysis of, laid the ground work for the realization of a Stille reaction catalytic in both palladium and tin. 94 Experimental Section Materials and Methods: All air or moisture sensitive reactions were carried out in oven- or flame- dried glassware under nitrogen atmosphere unless othenlvise noted. All commercial reagents were used without purification. All solvents were reagent grade. Diethyl ether and THF were freshly distilled from sodium/benzophenone under nitrogen. Benzene, toluene, DMSO, diisopropylethylamine and cyclohexane were freshly distilled from calcium hydride under nitrogen. Except as otherwise noted, all reactions were magnetically stirred and monitored by thin- Iayer chromatography with 0.25-mm precoated silica gel plates or capillary CO with a fused silica column. Flash chromatography was performed with silica gel 60 A (particle size 230-400 mesh ASTM). High performance liquid chromatography (HPLC) was performed with Ranin component analyticaV semiprep system. Yields refer to chromatographically and spectroscopically pure compounds unless otherwise stated. Infrared spectra were recorded on a Nicolet lR/42 spectrometer. Proton and carbon NMR spectra were recorded on a Varian Gemini-300, VXR 500 or INOVA 600 spectrometer. Chemical shifts for 1H NMR and 13C NMR are reported in parts per million (ppm) relative to CDCI3 (8 = 7.24 ppm for 1H NMR or 8 = 77.0 ppm for 13C NMR). Optical rotations were measured with a Perkin-Elmer Model 341 polarimeter. High resolution mass spectra (HRMS) data were obtained at either the Michigan State University Mass Spectrometry Service Center or at the Mass Spectrometry Laboratory of the 95 University of South Carolina, Department of Chemistry & Biochemistry. GC/MS were performed with a fused silica column (30 m by 0.25 mm id). Preparation of bisisopropylidene acetal (8): A 1-L, three-necked flask equipped with an overhead stirrer, heating mantle and condenser with drying tube was charged with D-mannitol (100 g, 0.549 mol), freshly distilled 1,2-dimethoxyethane (240 mL), and 2,2- dimethoxypropane (160 mL, 1.3 mol). The reaction mixture was stirred and stannous chloride (0.1 g) was added. The remaining neck was capped with a septum, and the stirred slurry was heated to reflux. Reflux was maintained until the mixture became clear (30 — 50 minutes) and was continued for 30 minutes after clarity was attained. The heating mantle was removed, and the solution was cooled below the reflux temperature and followed by the addition of pyridine (0.2 mL). After the solution was cooled to room temperature, it was transferred to a tared flask and concentrated on a rotary evaporator, beginning at room temperature and increasing the water bath to 100 °C. The semi-solid, which was white in color, was cooled to room temperature, and the residual solvent was removed with the vacuum pump to give 163 g of a white solid. According to the literature,13 the purity of the product is ~ 55%. Preparation of D-glyceraldehyde (9): 96 To a slurry of the bisisopropylidene of D-mannitol (36.0 g, 75.6 mmol, 55% purity) in CHZCIZ (360 mL) and a saturated aqueous NaHCOa solution (20 mL) was added Na|O4 (20 g, 93 mmol) portionwise (~ 2-3 minutes). After stirring for 2 hours at room temperature, MgSO4 (20 g) was added and stirred for an additional 10 minutes. The reaction mixture was then vacuum filtered, and the filtrate concentrated to give a thick yellow oil. The crude residue was purified by distillation (54 °C @ 15 mm Hg) to give 7.25 g (37%) of D-glyceraldehyde acetonide 9 as a clear oil. For 1H NMR data see below. Pb(0A c)4 procedure: To a cold (0 °C) solution of the bisisopropylidene of D-mannitol (36.0 g, 75.6 mmol, 55% purity) in EtOAc (260 mL) was added Pb(OAc)4 (52 g, 120 mmol) portionwise. The reaction mixture was warmed to room temperature and stirred for an additional 2.5 hours. The reaction mixture was filtered, and the filtrate was concentrated to give a clear syrup. Carbon tetrachloride (30 mL) was added to the residue and then evaporated under reduced pressure. This procedure was repeated three more times. The resulting residue was purified by distillation (40 °C, 3.6 mm Hg) to give 10.3 g (53%) of D-glyceraldehyde acetonide 9 as a clear oil. 1H NMR (300 MHz, CDCI3) 8 = 9.70 (d, J = 1.9 Hz, 1H), 4.37 (ddd, J = 7.4, 4.9, 1.9 Hz, 1H), 4.15 (ABq, J = 8.8, 7.4 Hz, 1H), 4.08 (ABq, J = 8.8, 4.9 Hz, 1H), 1.47 (s, 3H), 1.40 (s, 3H). The spectroscopic data was in complete agreement with the literature.13 97 Preparation of Allylic Alcohol (10): OH 10 To a cold (0 °C) solution of D-glyceraldehyde acetonide 9 (10.3 g, 79.5 mmol) in EtZO (145 mL) was added vinyl magnesium bromide (81 mL, 81 mmol, 1.0 M THF) dropwise over 30 minutes. The reaction was allowed to warm to room temperature over 45 minutes and then quenched with a saturated aqueous NH4CI solution (20 mL). The phases were separated, and the aqueous phase was extracted with CH2Cl2 (100 mL x 3). The combined organic phases were washed with brine, dried over M9804, and concentrated to give an oil. The crude residue was purified by flash chromatography on silica gel [Hex/EtOAc 1:1] to give 10.2 g (81%) of desired allylic alcohol 10 as a clear oil. For spectroscopic data see reference (14). Preparation of Epoxy alcohol (11): Kinetic resolution conditions: To a solution of Ti(O-i—Pr)4 (1.94 mL, 6.51 mmol) in CH20I2 (10 mL) at -30 °C was added (-)-diisopropyl tartrate (1.64 mL, 7.71 mmol) in CHzclz (10 mL). After 15 minutes of stirring, allylic alcohol 10 (1.0 g, 6.3 mmol) in CH20I2 (10 mL) was added dropwise, followed by anhydrous t-BuOOH in toluene (4.35 M, 0.75 98 mL, 3.30 mmol). The reaction was allowed to proceed at -20 °C for 24 hours and then quenched with saturated aqueous Na2803 (10 mL) and NaZSO4 (10 mL). The resulting mixture was stirred for two hours and then filtered through a pad of Celite on a glass frit filter. The filter cake was washed with anhydrous 320 until the paste became granular. The granular filter cake was scraped off into a flask with EtOAc (50 mL) and stirred at reflux for 5 minutes. It was then filtered through the same pad of Celite and washed with hot EtOAc (50 mL). The filtrate was washed with 50% KOH (15 mL x 2) and brine (25 mL), dried over MgSO4, filtered and concentrated to give 5.3 g of a yellow oil. The crude residue was purified by flash chromatography on alumina basic, activity Ill, (hexanes/EtOAc, 1:1) to provide 95 mg of epoxy alcohol 11 as a clear oil. For spectroscopic data see reference (19). Standard conditions: To a solution of Ti(O-i—Pr)4 (2.27 mL, 7.63 mmol) in CH2CI2 (10 mL) at -30 °C was added (-)-diisopropy| tartrate (1.70 mL, 8.01 mmol) in CHzclz (10 mL). After 15 minutes of stirring, allylic alcohol 10 (1.15 g, 7.28 mmol) in CH20I2 (20 mL) was added dropwise, followed by anhydrous t-BuOOH in toluene (4.35 M, 0.75 mL, 3.30 mmol). The reaction was allowed to proceed at -20 °C for 24 hours and then quenched with saturated aqueous Nazsoa (10 mL) and Na2SO4 (10 mL). The resulting mixture was stirred for two hours and then filtered through a pad of Celite on a glass frit filter. The filter cake was washed with anhydrous EtZO until the paste became granular. The granular filter cake was scraped off into a flask with EtOAc (50 mL) and stirred at reflux for 5 minutes. It was then 99 filtered through the same pad of Celite and washed with hot EtOAc (50 mL). The filtrate was washed with 50% KOH (15 mL x 2) and brine (25 mL), dried over MgSO4, filtered and concentrated to give 5.26 g of a yellow oil. For spectroscopic data see reference (19). Preparation of allylic ester (12): Ho 32 -‘ o Etosz/ 12 To a cold (0 °C) solution of bisisopropylidene acetal 8 (9.45 g, 19.8 mmol, 55% purity) in 5% aqueous NaHCOa (50 mL) was added dropwise a solution of NalO4 (6.3 g, 30 mmol) in water (50 mL). The ice bath was removed and stirred at room temperature for 1 hour. The reaction temperature was lowered back to 0 °C and then triethyI-ot-phosphonacetate (20.0 mL, 100 mmol) and 6 M K2003 (150 mL) were added. The ice bath was removed and stirred at room temperature for 24 hours. The reaction mixture was extracted with CH20I2 (200 mL x 4). The combined extracts were dried over MgSO4, filtered and concentrated. The cmde residue was purified by flash chromatography on silica gel [hexanes/EtOAc 1:1] to give 7.43 g (94%) of allylic ester 12 as a yellow oil. 1H NMR (300 MHz, CDCI3) 5 = 6.86 (dd, J = 15.7, 5.5 Hz, 1 vinyl H), 6.08 (dd, J = 15.7, 1.6 Hz, 1 vinyl H), 4.67 (dd, J: 12.64, 6.59 Hz, 1 H), 4.18 (q, J= 7.14 Hz, 2 H), 4.16 (dd, J: 8.2, 6.6 Hz, 1 H), 3.65 (dd, J: 8.2, 7.1 Hz, 1H), 1.46 (s, 3 H), 1.39 (s, 3 H), 1.27 (t, J = 7.14 Hz, 3 H). The spectroscopic data is in complete agreement with the reported literature.1E5 Preparation of allylic alcohol (13): 100 To a —78 °C solution of allylic ester 12 (5.99 g, 29.9 mmol) in CHZCIg (150 mL) was added DIBAL (75 mL, 1.0 M hexanes, 75 mmol) dropwise over 30 minutes. After stirring for 2 hours at -78 °C, the reaction was quenched with water (5 mL) and a saturated aqueous Rochelle’s salt solution (150 mL). The mixture was allowed to warm to room temperature and stir overnight. The biphasic mixture was separated, and the organic phase washed twice with saturated aqueous Rochelle’s salt solution. The combined aqueous phase was extracted three times with CH20I2. The combined organics were dried over MgSO4, filtered and concentrated to give 5.5 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/Et20 1:3] to give 3.54 g (75%) of allylic alcohol 13 as a clear oil. 1H NMR (300 MHz, CDCla) 6 = 5.96 (dt, J: 15.4, 4.94 Hz, 1 vinyl H), 5.71 (ddt, J: 15.4, 7.69, 1.65 Hz, 1 vinyl H), 4.52 (app q, J= 7.14 Hz, 1 H), 4.15 (dd, J: 4.94, 1.65 Hz, 2 H), 4.07 (dd, J: 7.69, 6.04 Hz, 1 H), 3.59 (t, J = 8.0 Hz, 1H), 1.46 (s, 1H), 1.41 (s, 3H), 1.38 (s, 3H). The spectroscopic data is in complete agreement with the reported literature.16 Preparation of 2,3-epoxy-1-ol (14): 14 To a solution of Ti(O-i-Pr)4 (4.52 mL, 15.2 mmol) in CHzclz (20 mL) at -30 °C was added (+)-diethyl tartrate (2.72 mL, 15.9 mmol) in CH2CI2 (20 mL). After 101 15 minutes of stirring, allylic alcohol 13 (2.28 g, 14.5 mmol) in CHzclg (40 mL) was added dropwise, followed by anhydrous t-BuOOH in toluene (2.18 M, 14.4 mL, 31.2 mmol). The reaction was allowed to proceed at -20 °C for 24 hours and then quenched with saturated aqueous Na2S03 (20 mL) and Na2804 (20 mL). The resulting mixture was stirred for two hours and then filtered through a pad of Celite on a glass frit filter. The filter cake was washed with anhydrous Et20 (~ 1 L) until the paste became granular. The granular filter cake was scraped off into a flask with EtOAc (50 mL) and stirred at reflux for 5 minutes. It was then filtered through the same pad of Celite and washed with hot EtOAc (50 mL). The filtrate was washed with 50% KOH (30 mL x 2) and brine (30 mL), dried over MgSO4, filtered and concentrated to give a yellow oil. The crude residue was purified by flash chromatography on silica gel [pet ether/Et20 1:7] to give 1.40 g (56%) of epoxy alcohol 14 as a clear oil. The spectroscopic data is in complete agreement with the reported literature.19 Preparation of dioI sulfide (17): OH 9% t-BUSMO 6.. 17 Water and t-BuOH were deoxygenated prior to use by the rapid passage of nitrogen through the solvent for at least 30 minutes. A solution of epoxy alcohol 14 (1.0 g, 5.7 mmol) in 0.5 M NaOH (29 mL) and t-BuOH (29 mL) was immersed in a preheated (70 °C) oil bath and stirred vigorously. A solution of t-butylthiol (0.82 mL, 7.2 mmol) in t-BuOH (10 mL) was added dropwise over 45 minutes. After stirring an additional 20 minutes, the reaction was allowed to cool 102 to room temperature and was then neutralized with a saturated aqueous NH4CI solution. After water was added to clarify the aqueous phase, the phases were separated. The aqueous phase extracted 5 times with CHzclz. The combined extracts were dried over Na2804, filtered and concentrated to give a yellow oil. Flash chromatography on silica gel [hexanes/EtOAc 1:1] afforded 1.1 g (75%) of diol sulfide 17 as a yellow oil. ‘H NMR (300 MHz, CDCIa) 6 = 4.32 (dt, J = 6.59, 3.85 Hz, 1 H), 4.06 (dd, J: 8.24, 6.59 Hz, 1 H), 3.89 (dd, J: 8.24, 7.14 Hz, 1 H), 3.61 (dt, J: 7.69, 3.85 Hz, 1 H), 3.39 (dd, J: 7.69, 3.85 Hz, 1 H), 3.00 (dABq, J = 13.19, 3.85 Hz, 1 H), 2.69 (dABq, J= 13.19, 8.24 Hz, 1 H), 1.42 (s, 3 H), 1.36 (s, 3 H), 1.25 (s, 9 H). The spectroscopic data is in complete agreement with the reported literature.19 Preparation of bisisopentylidene (18): °:‘. “ii To a 40 °C slurry of D~mannitol (50 g, 27 mmol) in 126 mL of DMF containing camphosulfonic acid (CSA) (1.92 g, 8.2 mmol) was added 3.3- dimethoxypentane (76 g, 58 mol) dropwise over 15 minutes. After stirring for 3 hours, the reaction was quenched with triethylamine (1.4 g, 14 mmol). The resultant solution was concentrated under vacuum at 60 °C to afford a crude oil. The oil was diluted with 400 mL of EtOAc and then washed with brine (270 mL x 2). The organic layer was dried over MgSOa, filtered, and concentrated under vacuum at 60 °C to yield a white solid. The solid was dried overnight under high 103 vacuum at 60 °C to give 77.31 g of bisisopentylidene acetal 19. According to literature,20 the purity of the bis-acetal is ~70% and the spectroscopic data is in complete agreement. 1H NMR 300 MHz (CDCI3): 6 = 3.72 - 4.20 (m, 8 H), 1.6 (m, 8 H), 0.86 (t, J = 7.42 Hz, 6 H), 0.89 (t, J: 7.42 Hz, 6 H). Preparation of allylic ester (20): lilo El \ Agar To a slurry of K|O4 (6.12 g, 26.6 mmol) and KHCOa (0.28 g, 0.25 mmol) in 1'" 55 Ci H20 (50 mL) at room temperature was added a solution of bisisopentylidene acetal 18 (11.0 g, 24.2 mmol, 70% purity) in THF (20 mL) dropwise over 5 - 10 minutes. After stirring for 3 hours at room temperature, the reaction mixture was cooled to 0 °C and followed by the addition of triethyl a-phosphonacetate (22.6 g, 20 mL, 100 mmol) and 150 mL of 6 M K2003. The resulting mixture was allowed to warm to room temperature and was stirred for 24 hr. The reaction mixture was extracted four times with CH20|2 and the combined extracts were dried over MgSO4, filtered and concentrated under reduced pressure to give 38 g of an oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc, 3:1) to provide 7.59 g (70%) of allylic ester 19 and 2.08 g (18%) of a diastereomeric mixture. IR (neat, 4 cm"): v = 2978, 2884, 1724, 1665, 1464, 1305, 1175, 1080, 978, 920; [01].; +41.6° (c 2.985, CHCla); 1H NMR (300 MHz, CDCla) 8 = 6.82 (dd, J = 15.66, 5.77 Hz, 1 H), 6.06 (d, J = 15.66 Hz, 1 H), 4.60 (m, 1 H), 4.13 (m, 1 H), 4.15 (q. .1: 7.14 Hz, 2 H), 3.56 (m, 1 H), 1.62 (q. J= 7.42 104 Hz, 2 H), 1.61 (q, J= 7.42 Hz, 2 H), 1.24 (t, J = 7.14 Hz, 3 H), 0.88 (t, J: 7.42 Hz, 3 H), 0.66 (t, J = 7.42 Hz, 3 H); ‘30 NMR (75 MHz, cock.) 6 = 165.91, 144.18, 122.39, 114.03, 75.22, 69.22, 60.49, 29.71, 29.33, 14.13, 8.04, 7.95; HRMS (CH4) m/z 229.1441 [(M + H)‘; calcd for C12H21O4, 229.1440]. Preparation of allylic alcohol (20): a 95” HO M 20 To a stirred solution of allylic ester 19 (3.40 g, 14.9 mmol) in 75 mL of CHZCIz at -78 °C was added DIBAL (38 mL, 1M hexanes, 38 mmol) over 30 min. The mixture was stirred at —78 °C for 3 hr, quenched with 3 mL of water and treated with 75 mL of saturated aqueous Rochelle’s salt. The solution was allowed to warm to room temperature, and the phases were separated. The organic phase was washed twice with Rochelle’s salt, and the combined aqueous phases were extracted with CH20I2. The combined extracts were dried with MgSO4, filtered and concentrated under reduced pressure. The product was purified by flash chromatography on silica gel [hexanes/EtOAc, 1:3] to provide 2.39 g (86%) of allylic alcohol 20. IR (neat, 4 cm"): v = 3416, 2974, 2941, 2662, 1464, 1172, 1076, 916; [0.]0 +27.2° (c 2.665, CHCla); 1H NMR (300 MHz, cock.) 5 = 5.91 (dtd, J= 15.38, 4.95, 0.824 H2, 1 H), 5.64 (ddt, J= 15.38, 7.69, 1.65 Hz. 1 H), 4.47 (q...pp 7.69 Hz, 1 H), 4.10 (dd, J: 4.94, 1.65 Hz, 2 H), 4.04 (qAB, J = 8.24, 6.32 Hz, 1 H), 3.50 (t, J = 8.24 6 H), 1.60 (dq, J = 7.42 Hz, 4 H), 0.86 (dt, J = 7.42 Hz, 6 H); 13c NMR (75 MHz, opera) 6 = 136.66, 126.19, 113.44, 77.64, 105 69.99, 62.63, 30.05, 29.84, 8.25, 8.16; HRMS (CH4) m/z 187.1335 [(M + H)*; calcd for C10H1903, 187.1334]. Preparation of epoxy alcohol (21 ): El 3 , El HOWVO ow 21 ""0 A solution of Ti(O-i-Pr)4 (3.70 mL, 12.4 mmol) in 20 mL CH20I2 was added to a flask filled with nitrogen and cooled to -30 °C. (+)-diethyI-L-tartrate (2.3 mL, 13 mmol) in 20 mL of dry CH2C|2 was added under stirring. After 15 minutes, allylic alcohol 20 (2.20 g, 11.8 mmol) in 40 mL of CH20l2 was added dropwise over 1 hour, followed by the addition of t-BuOOH in toluene (6.0 mL, 4.35 M, 26 mmol). The reaction was allowed to proceed at -20 °C for 26 hours, before being diluted with Et20 (50 mL) and then quenched with saturated aqueous solutions of Na2S03 and Na2SO4 (15 mL each). The resulting heterogeneous mixture was stirred vigorously for 2 hours and then filtered through a pad of Celite. The yellow paste was washed with anhydrous other until granular. The yellow paste was scraped into a flask with 50 mL of EtOAc. The heterogeneous mixture was heated to reflux for 5 minutes. The resulting mixture was filtered through the same Celite pad. The cake was washed with 50 mL of hot EtOAc. The filtrate was washed with 50% KOH (2 x 15 mL) and then brine, dried over MgSO4, filtered and concentrated to give 3.95 g of a crude oil. Purification by flash chromatography on silica gel [hexanes/EtOAc, 1:3] afforded 1.75 g (70%) of epoxy alcohol 21. IR (neat, 4 cm"): v = 3443, 2976, 2941, 2883, 1464, 1356, 1201, 1172, 1129, 1078, 916, 766; (egg, -12.2°(c1.40,CHCl3); 1H 106 NMR (300 MHz, CDCI3) 6 = 4.06 (m, 2 H), 3.92 (ddd, .1 = 12.64, 4.94, 2.20 Hz, 1 H), 3.77 (t, J: 6.59 Hz, 1 H), 3.64 (ddd, J: 12.64, 7.69, 3.85 Hz, 1 H), 3.12 (dt, .1 = 3.85, 2.20 Hz, 1 H), 3.07 (dd, J = 4.94, 2.20 Hz, 1 H), 2.01 (s, -OH), 1.60 (m, 4 H), 0.69 (t, J = 7.14 Hz, 3 H), 0.65 (t, J = 7.69 Hz, 3 H); 13c NMR (75 MHz, CDCI3) 6 = 113.9, 75.5, 66.3, 60.6, 55.3, 54.6, 29.5, 29.2, 6.0, 7.9; HRMS (oi-l.) m/z 203.1260 [(M + H)+; calcd for C10H1904, 203.1283]. Preparation of diol sulfide (22): Water and t-BuOH were deoxygenated prior to use by the rapid passage of nitrogen through the solvent for at least 30 minutes. A solution of the epoxy alcohol 21 (3.01 g, 14.8 mmol) in 74 mL of 0.5 M NaOH and 74 mL of t-BuOH was immersed in a preheated (70 °C) oil bath and stirred vigorously. A solution of t-butylthiol (2.2 mL, 20 mmol) in t-BuOH (30 mL) was added dropwise over 60 minutes. After stirring for an additional 30 minutes, the reaction was allowed to cool to room temperature and then neutralized with a saturated aqueous NH4CI solution. After water was added to clarify the aqueous phase, the phases were separated. The aqueous phase extracted 5 times with CHzclz. The combined extracts were dried over MgSO4, filtered and concentrated to give a yellow oil. Purification by flash chromatography on silica gel [Hex/EtOAc, 3:1] afforded 3.56 g (62%) of diol sulfide 22. IR (neat, 4 cm"): v = 3464, 2973, 2941, 2664, 1462, 1366, 1169, 1060, 1059, 920; [ofigg +51.3° (c 2.545, CHCI3); 1H NMR (300 MHz, com.) 6 = 4.26 (ddd, J = 7.69, 6.59, 4.40 Hz, 1 H), 4.07 (dt, J = 6.24, 6.59 Hz, 1 107 H), 3.84 (t, J: 7.69 Hz, 1 H), 3.63 (m, 1 H), 3.41 (dt, J= 4.40, 6.59 Hz, 1 H), 2.98 (dd, J: 13.19, 4.40 Hz, 1 H), 2.75 (d, J: 5.49 Hz, 1 H), 2.70 (dd, J: 13.19, 7.69 Hz, 1 H), 2.51 (d, J: 7.14 Hz, 1 H), 1.62 (m, 4 H), 1.31 (s, 9 H), 0.66 (Q, J: 7.69 Hz, 6 H); 130 NMR (75 MHz, CDCI3) 6 = 112.9, 79.3, 73.1, 71.4, 66.7, 42.6, 32.2, 31.0, 29.5, 29.0, 8.2, 8.0; HRMS (CH4) n1/2293.1785 [(M + H)*; calcd for C14H2904S, 293.1787]. Preparation of epoxy alcohol (23): El l ,Et 6H 23 To a solution of diol sulfide 22 (2.9 g, 9.9 mmol) and 2,6-di-t—butyl-4- ’0 I methylpyridine (6.13 g, 24.8 mmol) in CH20I2 (60 mL) was added Me30BF4 (2.26 g, 15.3 mmol) portionwise until TLC indicated that the diol was completely consumed (~ 1.5 hour @ 15 minute intervals). NaH (0.53 g, 21 mmol), which was washed prior to use with pentane or used as a 95% mineral oil suspension, was added dropwise as a suspension in CH2CI2 (10 mL). After stirring for 5 minutes, the solution was quenched with a saturated aqueous solution of NH4CI. Water was added and the phases were separated. The aqueous layer was extracted with CH2CI2 (3x). The combined organics were dried over Na2804, filtered, and concentrated to give a red oil. Purification by flash chromatography on silica gel [Hex/EtOAc, 1:3] afforded 1.46 g (73%) of epoxy alcohol 23 and 6.10 g of recovered 2,6-di-tert-butyl-4-methyl pyridine. IR (neat, 4 cm"): v = 3458, 2975, 2942, 2884, 1464, 1173, 1082, 918, 858; [01].; +4.8° (c 1.335, CHCla); ‘H NMR (300 MHz, cock.) 6 = 4.22 (dt, J= 4.94, 6.59 Hz, 1 H), 4.07 (dd, J = 6.24, 108 6.59 Hz, 1 H), 3.83 (dd, J: 8.24, 7.14 Hz, 1 H), 3.37 (q, J= 5.49 Hz, 1 H), 2.96 (ddd, J = 6.59, 3.65, 2.75 Hz, 1 H), 2.62 (dd, J = 4.94, 3.85 Hz, 1 H), 2.74 (dd, J = 4.94, 2.75 Hz, 1 H), 2.36 (d, J = 4.94 Hz, 1 H), 1.64 (m, 4 H), 0.90 (t, J: 7.69 Hz, 3 H), 0.89 (t, J: 7.14 Hz, 3 H); 13c NMR (75 MHz, cock.) 6 = 113.4, 77.0, 71.8, 65.9, 51.7, 45.3, 29.4, 26.9, 6.2, 6.0; HRMS (CH4) m/z 203.1263 [(M + H); calcd for C1oH1904, 203.1283]. Preparation of epoxy ketone (24): To a room temperature solution of epoxy alcohol 23 (0.42 g, 2.1 mmol) in CH2Cl2 (20 mL) were added DMSO (5.90 mL, 82.8 mmol), diisopropylethylamine (2.16 mL, 12.4 mmol), and sulfur trioxide pyridine (0.99 g, 6.21 mmol). After stirring for 30 mintues the reaction was quenched by the addition of an aqueous saturated solution of NH4CI (15 mL), followed by the addition of ether (40 mL). The phases were separated, and the organic layer was washed with brine (2x). The combined aqueous layers were extracted with ether (2x). The combined organic layers were dried over Na2804, filtered, and concentrated. The crude product was purified by flash chromatography on silica gel [hexanes/EtOAc, 3:1] to give 0.34 g (83%) of ketone 24 as a yellow oil. IR (neat, 4 cm"): v = 2977, 2944,2884,1730,1464,1383,1361,1201,1173,1130,1078,1061,912; [0E39-1-151.6°(C 1 .,43 CHCI3); 1H NMR (300 MHz, CDCI3) 6: 4. 63 (dd, J: 7. 69, 5.77 Hz, 1 H), 4.17 (dd, J: 8.51, 7.69 Hz, 1 H), 4.00 (m, 2 H), 2.99 (dd, J: 6.59, 4.67 Hz, 1 H), 2.79 (dd, J: 6.59, 2.47 Hz, 1 H), 1.64 (m, 4 H), 0.67 (t, J: 7.69 109 Hz, 6 H); ”C NMR (75 MHz, cock.) 6 = 205.1, 115.2, 79.7, 66.4, 50.4, 47.6, 29.0, 28.4, 8.0, 7.9; HRMS (CH4) m/2201.1122 [(M + H)*; calcd for C10H1704, 201.1127]. Preparation of alkene (25): "0 Three step tandem reaction via diol sulfide 22: To a solution of diol sulfide 22 (0.60 g, 2.0 mmol) and 2,6-di-tert-butyI-4- metylpyridine (1.05 g, 5.13 mmol) in CHzclz (10 mL) was added MesoBF4 (0.42 g, 2.6 mmol) portionwise until the diol was completely consumed (~ 1 hour). NaH (0.10 g, 4.3 mmol), which was washed prior to use with pentane, was added dropwise as a suspension in CHzclz (3 mL). After stirring for 1 hour, the solution was quenched with a saturated aqueous solution of NH4CI. The phases were separated, and the aqueous layer extracted with CH20I2 (3x), dried over Na2804, filtered, and concentrated to give 1.45 g of crude material. Swem Oxidation: To a solution of oxalyl chloride (0.36 mL, 4.1 mmol) in CHgClz (12 mL) at -78 °C was slowly added a solution of DMSO (0.58 mL, 8.2 mmol) solution in CHgClz (1 mL). After 5 minutes, a solution of crude epoxy alcohol 23 in CHch2 (6 mL) was added dropwise. After another 15 minutes, diisopropylethylamine (2.86 mL, 16.4 mmol) was added, and the reaction mixture was allowed to warm to room temperature. The reaction was diluted with ether (40 mL) and water (20 mL), and the phases were separated. The organic phase was washed with 110 water, brine and then dried over Na2304, filtered and concentrated to give crude 24 as a yellow oil. Wittig Olefination: To a cold (0 °C) mixture of methyltriphenylphosphonium bromide (0.81 g, 2.3 mmol) in THF (8 mL) was added n-BuLi (1.5 mL, 2.4 mmol) dropwise. The reaction mixture was warmed to room temperature and stirred for 30 minutes, cooled back to 0 °C and then a solution of crude ketone 24 in THF (5 mL) was added dropwise. After stirring for 1 hour, the reaction was quenched with a saturated aqueous NH4CI solution. Ether was added and the phases were separated. The aqueous phase was extracted with ether (2x). The combined organics were washed with water, brine and then dried over Na2804, filtered and concentrated to give 1.65 g of crude material. Purification by flash chromatography on basic alumina, activity III [hexanes/EtOAc 5%] afforded 0.15 g (36%) of alkene 25. For spectroscopic data see below. Optimized olefination procedure: To a cold (0 °C) mixture of methyltriphenylphosphonium bromide (7.03 g, 19.7 mmol) in THF (30 mL) was added NaHMDS (18.3 mL, 18.3 mmol) dropwise over ~ 20 minutes. The reaction mixture was warmed to room temperature and stirred for 30 minutes and then cooled to 0 °C at which time a solution of ketone 24 in THF (4 mL) was added dropwise. The reaction mixture was warmed to room temperature and stirred for 3.5 hours. The reaction was quenched by the addition of a saturated aqueous NH4CI solution (30 mL). Water (30 mL) and 320 (90 mL) were added, and the phases separated. The aqueous layer was 111 extracted with EtZO (25 mL x 2). The combined organic phase was washed with brine (25 mL), dried over Na2804, filtered and concentrated to give 6.83 g of crude material. Purification by flash chromatography on silica gel [hexanes/EtOAc, 3:1] afforded 0.60 g (80%) of alkene 25. IR (neat, 4 cm"): v = 2977, 2944, 2884, 1464, 1196, 1173, 1080, 1059, 916; [ofigg +101 .9° (c 1.245, CHCIa); 1H NMR (300 MHz, CDCla): 6 = 5.27 (s, 1 H), 5.22 (s, 1 H), 4.57 (dd, J: 6.79, 6.32 Hz, 1 H), 4.10 (qAB, J= 7.97, 6.32 Hz, 1 H), 3.61 (qAB, J= 8.79, 7.97 Hz, 1 H), 3.43 (dt, J= 3.85, 0.62 Hz, 1 H), 2.90 (qAB, J= 5.77, 4.12 Hz, 1 H), 2.54 (qAB, J = 5.77, 2.75 Hz, 1 H), 1.66 (m, 4 H), 0.90 (m, 6 H); “C NMR (75 MHz, cool.) 6 = 143.0, 113.2, 113.1, 76.7, 69.4, 50.5, 49.4, 29.6, 29.2, 6.1; HRMS (CH4) m/z199.1326 [(M + H)“; calcd for C11H1903, 199.1334]. Preparation of hydroxy sulfide (26): Et 7? OH ’0 P118 5 To a solution of sodium benzenethiolate (0.17 g, 1.2 mmol) in THF (10 mL) at room temperature was added dropwise (~ 15 minutes) a solution of epoxide 25 (0.19 g, 0.96 mmol) in THF (2 mL). After stirring for 1.5 hours, the reaction was quenched with a saturated aqueous NH4CI solution. Et20 and water were added and the phases were separated. The aqueous phase was extracted with ether (2x). The combined organics were dried over M9804, filtered and concentrated to give 0.34 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc, 10 %] afforded 0.20 g (67%) of hydroxy sulfide 26 as an oil. IR (neat, 4 cm"): v = 3451, 2975, 2940, 2882, 1564, 112 1462,1464,1439,1356,1267,1196,1173,1060,1059.1026,916,739,691; (egg, +53.6° (c 1.04, CHCI3); 1H NMR (300 MHz, cock.) 6 = 7.30 (m, 5 H), 5.28 (s, 1 H), 5.24 (s, 1 H), 4.57 (dd, J: 8.79, 6.32 Hz, 1 H), 4.17 (m, 1 H), 4.13 (qAB, J = 7.97, 6.32 Hz, 1 H), 3.59 (qAB, J= 8.79, 7.97 Hz, 1 H), 3.26 (qAB, J= 13.74, 8.52 Hz, 1 H), 3.04 (qAB, J= 13.74, 8.52 Hz, 1 H), 2.94 (d, J: 3.85 Hz, -OH), 1.64 (m, 4 H), 0.89 (t, J: 7.42 Hz, 6 H); 13c NMR (75 MHz, CDCIa) 6 = 146.3, 135.0, 130.0, 129.1, 126.7, 113.2, 113.0, 76.9, 70.4, 69.8, 40.4, 29.7, 29.3, 8.1; HRMS (CH4) m/z 307.1362 [(M - H)‘; calcd for C17H23038, 307.1368]. Preparation of ot-acetoxy sulfide (27) via pummerer rearrangement: a Et Ac 9 PhS ’ ON: 27 To a solution of phenyl sulfide 26 (0.101 g, 0.327 mmol) in CH20I2 (7 mL) at -78 °C was added dropwise (-_~10 minutes) a solution of m-CPBA (0.056 g, 0.33 mmol) in CHZCIz (1 mL). After stirring for 5 minutes at -78 °C, the reaction mixture was allowed to warm to room temperature over 30 minutes. The reaction mixture was quenched by washing with 1 M NaOH (0.5 mL x 2), water (2x) and brine. The combined organic layers were dried over MgSO4, filtered and concentrated to give 0.12 g (100%) of a yellow oil. Pummerer Rearrangement: The above crude sulfoxide and sodium acetate (0.10 g, 1.0 mmol) were dissolved in acetic anhydride (2 mL). The reaction mixture was heated to reflux over 30 minutes and then stirred at reflux for 3 hours. The reaction mixture was 113 concentrated. The resulting residue was diluted with CH20I2 (10 mL) and filtered to remove the excess sodium acetate. The filtrate was washed with a saturated aqueous NaHCOa solution (4 mL x 2), water and brine. The combined organic phase was dried over MgSO4, filtered and concentrated. The residue was evaporated from toluene several times under high vacuum to remove the residual acetic anhydride. Purification by flash chromatography on silica gel [hexanes/EtOAc, 10%] afforded 42 mg (38%) of a diastereomeric mixture of ot-acetoxy sulfide 27 as a thick yellow oil. 1H NMR (300 MHz, CDCla): 8 = 7.27- 7.49 (m, 10 H) 6.30 (d, J: 5.77 Hz, 1 H), 6.24 (d, J: 5.49 Hz, 1 H), 5.55 (s, 1 H), 5.42 (d, J: 5.77 Hz, 1 H), 5.39 (s, 1 H), 5.35 (d, J: 5.49 Hz, 1 H), 5.25 (s, 2 H), 4.53 (m, 2 H), 4.18 (m, 2 H), 3.58 (m, 2 H), 2.08 (s, 3 H), 2.05 (s, 3 H), 2.03 (s, 3 H), 2.03 (s, 3 H) 1.62 (m, 6 H), 0.90 (t, J: 7.42 Hz, 6 H), 0.89 (t, J: 7.42 Hz, 6 H) ; 13C NMR (75 MHz, CDCla) 8 = 169. 5, 169.4, 169.2, 169.2, 142.0, 133.6, 133.4, 131.5, 131.2, 129.1, 129.1, 128.6, 128.5, 115.9, 115.4, 113.2, 113.2, 81.7, 79.7, 76.0, 74.1, 73.4, 70.3, 70.2, 29.7, 29.3, 20.9, 20.8, 8.2, 8.0. Preparation of TBS-ether (29): 61 *3 O OTBS ’0 P118 3., To a solution of alcohol 26 (0.13 g, 0.42 mmol) in CHZClz (5 mL) at —78 °C were added diisopropylethylamine (0.24 mL, 1.3 mmol) and TBSOTf (0.15 mL, 0.67 mmol). After stirring for 20 minutes at -78 °C, the reaction was quenched with water (1 mL) and then allowed to warm to room temperature. The reaction mixture was diluted with Etze and saturated aqueous NH4CI and then the phases 114 were separated. The organic phase was washed with water and brine, dried over MgSO4, filtered and concentrated to give 0.27 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc, 10%] afforded 0.13 g (75%) of TBS-ether 29 as an oil. For spectroscopic data see below. In situ protection via epoxide 25: To a solution of sodium benzenethiolate (0.59 g, 4.5 mmol) in THF (35 mL) at room temperature was added dropwise (~ 10 minutes) a solution of epoxide 25 (0.68 g, 3.4 mmol) in THF (8 mL). After stirring for 2.5 hours, the reaction was quenched by the addition of a solution of TBSOTf (1.30 mL, 5.47 mmol) and i-Pl’zNEt (1.90 mL, 10.9 mmol) in THF (10 mL). After stirring for an additional 5 minutes, Et20 (70 mL) and water was added, and the phases were separated. The aqueous phase was extracted with ether (2x). The combined organics were was washed with brine, dried over MgSO4, filtered and concentrated to give 1.95 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc, 0 —> 5%] afforded 0.80 g (55%) of TBS-ether 29 as a yellow oil, 0.38 g (36%) of unprotected alcohol 26 as a yellow oil and 59 mg (9%) of recovered epoxide 25 as an oil. For spectroscopic data see below. Oxidation and olefination via 35: To a solution of alcohol 35 (2.26 g, 5.30 mmol) in CH20I2 (55 mL) at 0 °C was added i-PerEt (5.50 mL, 31.8 mmol), DMSO (10 mL) and a heterogenous solution of SOgopyridine (2.53 g, 15.9 mmol) in DMSO (5 mL). The ice bath was removed and the reaction was stirred at room temperature for 30 minutes. The reaction was quenched with the addition of a saturated aqueous solution of 115 NH4CI (90 mL). The reaction mixture was diluted with 320 (190 mL), and the phases were separated. The organic phase was washed with brine (25 mL x 2). The combined aqueous phases were extracted with Et20 (30 mL x 2). The organics were dried over MgSO4, filtered and concentrated to give 3.09 g of crude 36 as a yellow oil. To a cold (0 °C) mixture of methyltriphenylphosphonium bromide (2.83 g, 7.95 mmol) in THF (30 mL) was added NaHMDS (6.4 mL, 6.4 mmol, 1 M THF) dropwise over ~ 20 minutes. The reaction mixture was warmed to room temperature and stirred for 30 minutes, cooled to 0 °C and then a solution of crude ketone 36 in THF (7 mL) was added dropwise. The reaction mixture was warmed to room temperature and stirred for 4 hours. The reaction was quenched with the addition of a saturated aqueous NH4CI solution (7 mL). Water (7 mL) and Et20 (110 mL) were added and the phases separated. The organic phase was washed with brine (10 mL x 2), dried over M9804, filtered and concentrated. Purification by flash chromatography on silica gel [hexanes/EtOAc, 10 -—> 25%] afforded 1.78 g (79%, 2 steps) of alkene 29 as an oil. IR (neat, 4 cm"): v = 2930, 2884, 2859, 1471, 1464, 1439, 1256, 1173, 1080, 1005, 920, 837, 777, 737, 691; [6E], +43.1° (c 0.78, CHCIa); 1H NMR (300 MHz, CDCla): 8 = 7.30 (m, 5 H), 5.34 (s, 1 H), 5.23 (s, 1 H), 4.57 (dd, J: 9.07, 6.04 Hz, 1 H), 4.27 (dd, J: 7.42, 4.94 Hz, 1 H), 4.10 (dd, J: 7.69, 6.04 Hz, 1 H), 3.52 (dd, J: 9.06, 7.69 Hz, 1 H), 3.05 (qAB, J= 13.46, 4.94 Hz, 1 H), 2.97 (qAB, J = 13.46, 7.42 Hz, 1 H), 1.66 (m, 4 H), 0.89 (m, 6 H), 0.85 (s, 9 H), 0.035 (s, 3 H), -0.021 (s, 3 H); 13c NMR (75 MHz, CDCI3) 6 .-= 147.9, 136.6, 129.1, 128.9, 116 125.9, 112.9, 112.5, 75.2, 73.4, 70.6, 41.6, 29.9, 29.6, 25.8, 25.7, 18.2, 8.2, 8.1, -4.7, -4.9; HRMS (CH4) m/z421.2228 [(M - H)*; calcd for CzaH370388i, 421.2233]. Preparation of sulfoxide (30): Et Et pl ores 9A: ”18% To a solution of phenyl sulfide 29 (1.05 g, 2.48 mmol) in 0142012 (50 mL) at —78 °C was added dropwise (~10 minutes) a solution of m-CPBA (0.43 g, 2.5 mmol) in CH20|2 (10 mL). After stirring for 5 minutes at —78 °C the reaction mixture was judged complete by TLC, and was then quenched by the addition of 1 M NaOH (3 mL) and allowed to warm to room temperature over 30 minutes. The phases were separated, and the organic phase washed with 1M NaOH (3 mL), water (3 mL x 2) and brine (4 mL), dried over MgSO4, filtered and concentrated to give 1.13 g (100%) of cnlde sulfoxide 30 as a yellow oil. 1H NMR (300 MHz, cock.) 6 = 7.45 - 7.65 (m, 10 H), 5.45 (s, 1 H), 5.40 (s, 1 H), 5.35 (s, 1 H), 5.34 (s, 1 H), 4.45 -4.70 (m, 4 H), 4.10 (dd, J: 7.42, 6.04 Hz, 1 H), 4.05 (dd, J: 7.42, 6.04 Hz, 1 H), 3.57 (dd, J: 9.07, 7.69 Hz, 1 H), 3.47 (dd, J = 9.07, 7.69 Hz, 1 H), 3.10 (qAB, J= 13.19, 6.59 Hz, 1 H), 2.95 (qAB, J= 13.19, 6.67 Hz, 1 H), 2.63 (qAB, J= 12.91, 2.20 Hz, 1 H), 2.70 (qAB, J= 12.91, 10.44 Hz, 1 H), 1.62 (m, 8 H), 0.79 — 0.96 (m, 30 H), 0.08 (s, 3 H), 0.06 (s, 3 H), 0.05 (s, 3 H), 0.03 (s, 3 H); 1“‘c NMR (75 MHz, cock.) 6 = 149.1, 147.5, 146.0, 144.5, 132.9, 131.3, 130.8, 129.3, 129.0, 127.4, 127.1, 124.2, 123.6, 115.3, 113.2, 117 112.7, 75.5, 75.0, 70.6, 70.3, 70.1, 68.2, 66.2, 29.7, 29.4, 25.8, 25.7, 18.2, 18.0, 8.0, -2.9, -4.5, -5.0, -5.2. Preparation of ot-acetoxy sulfide (31 ): Et Et ores 9»: OAc 31 A solution of trifluoroacetic acid anhydride (0.20 mL, 1.4 mmol) in acetic anhydride (1 mL) was stirred at room temperature for 6 hours. A solution of crude sulfoxide 30 (0.42 g, 0.95 mmol) in Ac20 (1 mL) was added and followed by the addition of 2,6-Iutidine (0.22 mL, 1.9 mmol). After stirring for 15 hours at room temperature, the reaction was concentrated to give a dark red residue. CH2Cl2 was added to the residue and the solution was washed with a saturated aqueous NaHCOa solution and brine. The organic phase was dried over M9804, filtered and concentrated to give a red oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5%] afforded 0.34 g (80%) of ot-acetoxy sulfide 31 as a diastereomeric mixture. 1H NMR (300 MHz, CDCla) 6 = 7.22- 7.46 (m, 10 H) 6.14 (d, J=4.12 Hz, 1 H), 6.10 (d, J=7.14 Hz, 1 H), 5.55 (s, 1 H), 5.50 (s, 1 H), 5.43 (s, 1 H), 5.22 (s, 1 H), 4.62 (m, 2 H), 4.42 (d, J: 3.85 Hz, 1 H), 4.35 (d, J: 7.14 Hz, 1 H), 4.21 (dd, J: 7.69, 6.04 Hz, 1 H), 4.14 (dd, J: 7.69, 6.04 Hz, 1 H), 3.59 (dd, J: 9.07, 7.69 Hz, 1 H), 3.54 (dd, J: 9.07, 7.69 Hz, 1 H), 2.01 (s, 3 H), 2.00 (s, 3 H), 1.65 (m, 6 H), 0.90 (m, 30 H), 0.08 (s, 3 H), 0.05 (s, 3 H), 0.03 (s, 3 H), 0.01 (s, 3 H); 13c NMR (75 MHz, CDCI3) 6 = 169.5, 169.4, 169.2, 169.2, 142.0, 133.6, 133.4, 131.5, 131.2, 129.1, 129.1, 128.6, 128.5, 115.9, 115.4, 118 113.2, 113.1, 81.7, 79.7, 76.0, 74.0, 73.4, 70.3, 70.2, 29.7, 29.3, 20.9, 20.8, 8.2, 8.0; HRMS (Cl) m/z 479.2277 [(M - H)"; calcd for CstagOsssi, 479.2287]. Reduction of ot-acetoxy sulfide (31) to give alcohol (32): E1 OTBS g—Sga 32 To a solution of ot-acetoxy sulfide 31 (0.809, 1.8 mmol) in THF (30 mL) at 0 °C was added LiBEtaH (Super-Hydride“) (5.6 mL, 5.6 mmol, 1.0 M THF) dropwise (~15 minutes). The ice bath was removed and the reaction stirred at room temperature for 45 minutes. The reaction was quenched by the addition of a saturated aqueous NH4CI solution (6 mL) and glycerol (1.7 mL, 0.3 mL/mmol). After stirring for 4 hours, the reaction mixture was diluted with 320 (30 mL) and the phases separated. The organic phase was washed with brine (5 mL x 2), dried over MgSO4, filtered and concentrated to give 1.2 g of a greenish-yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc, 25%] afforded 0.46 g (79%) of alcohol 32 as a yellow oil. 1H NMR (300 MHz, CDCI3) 8 = 5.38 (s, 1 H), 5.26 (s, 1 H), 4.52 (dd, J: 8.79, 6.59 Hz, 1 H), 4.22 (dd, J: 6.59, 3.85 Hz, 1 H), 4.12 (dd, J: 7.69, 6.04 Hz, 1 H), 3.53 (dd, J: 8.79, 7.69 Hz, 1 H), 3.53 (m, 1 H), 3.44 (m, 1 H), 1.65 (m, 4 H), 0.89 (m, 6 H) 0.89 (s, 9 H), 0.07 (s, 3 H), 0.04 (s, 3 H); "’0 NMR (75 MHz, CDCI3) 6 = 146.1, 113.7, 112.6, 75.7, 74.5, 70.2, 66.9, 29.8, 29.4, 25.8, 18.1, 8.2, 8.1, -4.6, -5.1; HRMS (Cl) m/2331.2311 [(M + H)*; calcd for C17H3504Si, 331.2305]. Oxidation of alcohol (32) to give aldehyde A (33): 119 El ores 9 H .' E1 0 A (33) To a solution of oxalyl chloride (0.10 mL, 1.2 mmol) in CH2CI2 (4 mL) at -78 °C was slowly added a solution of DMSO (0.17 mL, 2.4 mmol) in CHZCIZ (0.1 mL). After 5 minutes, a solution of alcohol 32 (0.195 g, 0.594 mmol) in CHzclz (1.5 mL) was added dropwise. After another 15 minutes, r’-Pr2NEt (0.83 mL, 4.8 mmol) was added, and the reaction mixture was allowed to warm to room temperature. The reaction was diluted with ether (12 mL) and water (3 mL), and the phases were separated. The organic phase was washed with water (3 mL) and brine (3 mL). The combined aqueous phases were extracted with EtZO (5 mL). The combined organics were dried over Na2804, filtered and concentrated to give 0.22 g a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5%] afforded 0.16 g (82%) of aldehyde 33 as a yellow oil. 1H NMR (300 MHz, CDCIa) 8 = 9.40 (cl, J = 1.65 Hz, 1 H), 5.49 (s, 1 H), 5.33 (d, J = 0.82 Hz, 1 H), 4.52 (dd, J: 8.79, 6.32 Hz, 1 H), 4.41 (s, 1 H), 4.07 (dd, J = 7.69, 6.32 Hz, 1 H), 3.60 (dd, J: 9.07, 7.69 Hz, 1 H), 1.68 (m, 4 H), 0.90 (s, 9 H), 0.89 (m, 6 H), 0.07 (s, 3 H), 0.05 (s, 3 H); “’0 NMR (75 MHz, CDCla) 6 = 199.7, 142.5, 115.9, 113.3, 79.4, 76.1, 69.5, 29.7, 29.2, 25.6, 18.2, 8.2, 8.0, -5.0. Preparation of sulfide diol (34): 3 O I ""0 «‘r” E 120 Aqueous NaOH and t-BuOH were deoxygenated prior to use by the rapid passage of nitrogen through the solvent for at least 30 minutes. A solution of epoxy alcohol 21 (2.0 g, 9.9 mmol) in 50 mL of 0.5 M NaOH and 50 mL of t-BuOH was immersed in a preheated (~88 °C) oil bath. The reaction mixture was stirred vigorously. Thiophenol (1.42 mL, 13.8 mmol) was dissolved in t-BuOH (20 mL) and added dropwise over 2 hours. After stirring for an additional 10 minutes, the reaction was allowed to cool to room temperature and was then neutralized with a saturated aqueous NH4CI solution (50 mL). The phases were separated, and the aqueous phase extracted with CH2CI2 (75 mL x 5). The combined organic extracts were washed with a saturated aqueous NH4CI solution (50 mL) and brine (20 mL), dried over MgSO4, filtered and concentrated to give 4.6 g of yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25%] afforded 2.1 g (69%) of diol sulfide 34. IR (neat, 4 cm"): v = 3460, 2973, 2926, 2884, 1584, 1461, 1464, 1440, 1376, 1337, 1292, 1172, 1092, 1080, 1026, 912, 740; [egg], +31 .0° (c 0.90, CHCIa); 1H NMR (300 MHz, 00013) 6 = 7.3 (m, 5 H), 4.25 (ddd, J: 7.69, 6.59, 4.40 Hz, 1 H), 4.05 (dd, J: 8.2, 6.59 Hz, 1 H), 3.85 (app t, J: 7.97 Hz, 1 H), 3.65 (m, 1 H), 3.49 (m, 1 H), 3.56 (ABq, J= 14.01, 3.57 Hz, 1 H), 2.99 (ABq, J= 14.01, 6.52 Hz, 1 H), 2.76 (d, J: 5.22 Hz, -OH), 2.52 (d, J: 6.32 Hz, -OH), 1.64, (m, 4 H), 0.88 (t, J: 7.14 Hz, 3 H), 0.66 (t, J: 7.14 Hz, 3 H); “’0 NMR (75 MHz, CDCI3) 6 = 134.6, 129.6, 129.1, 126.6, 113.0, 76.3, 72.9, 70.9, 66.7, 36.7, 29.5, 28.9, 8.2, 8.0; HRMS (El) [TI/23121403 [M+; calcd for C15H24O4S, 312.1395]. 121 Selective mono-protection of diol (34) to give TBS-ether (35): E! 6H as To a solution of diol sulfide 34 (4.01 g, 12.8 mmol) in CH20I2 (180 mL) at E1 to 0 °C were added i-PrgNEt (2.67 mL, 15.4 mmol) and TBSTOf (3.23 mL, 14.1 mmol). The reaction mixture was stirred for ~1.5 hours and then quenched by the addition of an aqueous solution of NH4CI (10 mL). The reaction mixture was concentrated to ~ half volume. Water (6 mL) and 320 (160 mL) were and the phases were separated. The organic phase was washed with brine (10 mL), dried over MgSO4, filtered and concentrated to give 5.26 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/ EtOAc 5% -+ 10%] to afford 3.82 g (70%) of mono-protected TBS-ether 35 as an oil and 0.84 g (21%) of recovered diol 34. For 35: IR (neat, 4 cm"): v = 2931, 2886, 2858, 1585, 1482, 1472, 1464, 1439, 1360, 1253, 1172, 1082, 923, 837, 777, 736; [egg—256° (c 0.65, CHCI3); 1H NMR (300 MHz, CDCla) 6 = 7.35 (m, 5 H), 4.29 (dt, J = 3.02, 6.59 Hz, 1 H), 4.00 (dd, J: 6.59, 7.69 Hz, 1 H), 3.81 (app t, J = 7.69 Hz, 1 H), 3.70 (dt, J = 7.42, 3.30 Hz, 1 H), 3.62 (dt, J = 3.30, 7.69 Hz, 1 H), 3.33 (ABq, J= 13.18, 4.39 Hz, 1 H), 3.21 (ABq, J= 13.18, 4.39 Hz, 1 H), 2.32 (d, J: 7.97 Hz, -OH), 1.61 (m, 4 H), 0.92 (m, 15 H), 0.08 (s, 3 H), 0.05 (s, 3 H); 13C NMR (75 MHz, CDCla) 8 = 137.2, 129.2, 128.8, 125.8, 113.1, 74.6, 72.5, 72.1, 66.6, 38.6, 29.2, 28.8, 25.8, 18.1, 8.3, 8.0, -4.3, -4.8; HRMS (El) m/z 426.2267 [M*; calcd for 022H3304SSi, 426.2260]. 122 Preparation of ketone (36): El Et ores 943g we“ To a solution of alcohol 35 (3.82 g, 8.95 mmol) in CHZCIZ (90 mL) at 0 °C were added i-PerEt (9.35 mL, 53.7 mmol), DMSO (18 mL) and a heterogenous solution of Sanpyridine (4.27 g, 26.9 mmol) in DMSO (7 mL). The ice bath was removed and stirred at room temperature for 30 minutes. The reaction was quenched by the addition of a saturated aqueous solution of NH4CI (65 mL). The reaction mixture was diluted with 320 (150 mL) and the phases were separated. The organic phase was washed with brine (20 mL x 2). The combined aqueous phases were extracted with Et20 (30 mL x 2). The organics were dried over MgSO4, filtered and concentrated to give 4.73 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to afford 2.73 g (72%) of ketone 36 as a yellow oil. IR (neat, 4 cm"): v = 2932, 2884, 2859, 1734, 1472, 1464, 1441, 1362, 1256, 1201, 1173, 1086, 1026, 914, 839, 810, 779, 741; [6E], +6.7° (c 1.015, CHCI3); 1H NMR (300 MHz, CDCI3) 6 = 7.3 (m, 5 H), 4.64 (dd, J: 7.69, 7.14 Hz, 1 H), 4.54 (t, J: 5.22 Hz, 1 H), 4.27 (dd, J = 8.52, 7.69 Hz, 1 H), 4.07 (dd, J: 8.52, 7.14 Hz, 1 H), 3.35 (ABq, J= 13.19, 5.22 Hz, 1 H), 3.16 (ABq, J= 13.19, 5.22 Hz, 1 H), 1.63 (dq, J= 3.30, 7.42 Hz, 4 H), 0.66 (m, 15 H), 0.08 (s, 3 H), 0.05 (s, 3 H); 13c NMR (75 MHz, CDCI3) 6 = 207.5, 135.9, 129.6, 128.9, 126.4, 114.8, 78.4, 75.2, 66.0, 37.9, 29.2, 28.7, 25.7, 18.1, 8.0, -4.8, -5.0; HRMS (El) m/z 395.1712 [(M - Et)"; calcd for C20H3104SSI, 395.1718]. 123 Preparation of fragment B: 37 W TMS To a cold (0 °C) solution of EtMgBr (11 mL, 33 mmol, 3.0 M EtZO) was added dropwise (~45 minutes) a solution of trimethylsilylacetylene (4.2 mL, 30 mmol) in THF (45 mL). After stirring for an additional 10 minutes at 0 °C, the reaction was immersed into a preheated oil bath (55 °C) and stirred for 1 hour and then recooled to 0 °C. The septum was quickly removed and Cul (0.11 g, 0.60 mmol) was added. The reaction vessel was reimmersed into the oil bath (55 °C) and 2,3-dibromopropene (3.7 mL, 36 mmol) was added dropwise over 1.5 hours. After stirring an additional 4 hours, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (10 mL) and then diluted with Eth (125 mL). The phases were separated, and the organics were washed with brine (5 mL x 2), dried over MgSO... filtered and concentrated to give 9.73 g of a reddish-yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 5%] to afford 6.02 g (93%) of fragment B as a light yellow oil. 1H NMR (300 MHz, CDCla) 8 = 6.0 (q, J= 1.65 Hz, 1 H), 5.53 (q, J= 1.65 Hz, 1 H), 3.35 (t, J = 1.65 Hz, 2 H), 0.16 (s, 9 H); 13C NMR (75 MHz, CDCI3) 8 = 126.7, 117.9, 101.0, 88.9, 32.7, -0.12; HRMS (El) m/2215.9967 [M*; calcd for CaHraBrSi, 215.9970]. Preparation of (Z)-[3-iodo acid (48): O OH I/ 48 124 Ethyl 2-butynoate (4.16 mL, 35.7 mmol) was added to a sealed tube containing hydriodic acid (7 mL, 48% aq) and heated to 110 °C. After heating for 12 hours, the sealed tube was removed from the oil bath and allowed to cool to room temperature. The resultant crystals were filtered with the aid of a glass frit filter and washed three times with cold water. If crystallization was slow the sealed tube was inserted into an ice bath. The wet crystals were dried overnight in vacuo over KOH to give 3.0 g (40%) of (Z)-B-iodo acid 48 as a white solid. The aqueous filtrate was diluted with 320 and separated the phases. The aqueous phase was extracted twice with Etzo. The combined organics were dried over M9804, filtered and concentrated to give 4.45 g (52%) of (2)-B-iodo ethyl ester 49. Resubjection of the ethyl ester to the reaction conditions afforded the desired (Z)-B-iodo acid 48 quantitatively. mp = 66 °C; 1H NMR (300 MHz, CDCla) 8 = 12.54 (s, 1 H), 6.42 (s, 1 H), 3.32 (s, 1 H). The spectroscopic data is in complete agreement with the reported literature.34 lsomerization of (2)-B-iodo acid (48) to give (E)-B-iodo acid fragment (D): IWOH D o The (Z)-B-iodo acid 48 was heated to 135 °C in a sealed tube for 24 hours. From 1H NMR, the isomerization was not total but gave the desired E-isomer (D) in a 3:1 ratio. With careful flash chromatography on silica gel [hexanes/EtOAc 25%, 1% MeOH] the two isomers were separated. mp = 66 °C; 1H NMR (300 MHz, CDCI3) 8 = 12.54 (s, 1 H), 6.42 (s, 1 H), 3.32 (s, 1 H). The spectroscopic data is in complete agreement with the reported literature.34 125 Preparation of alcohol (50) [model AIB coupling]: OH \\ TMS 50 Vinyl bromide B (0.20 g, 0.92 mmol) and MgBrzoEtZO (0.39 g, 1.5 mmol) were dissolved in THF (10 mL) and cooled to —78 °C. t-BuLi (1.1 mL, 1.8 mmol, 1.7 M pentane) was added dropwise over ~8 minutes. After stirring for an additional 5 minutes at -78 °C, valeraldehyde (0.065 mL, 0.61 mmol) was added dropwise. After stirring for 1 hour at -78 °C, the reaction was allowed to warm to room temperature over 30 minutes and then stirred for an additional 15 minutes. The reaction was quenched by the addition of a saturated aqueous NH4CI solution (2 mL). Et20 (20 mL) was added and the phases were separated. The aqueous phase was extracted with EtZO (2x). The combined organics were washed with brine, dried over MgSO4, filtered and concentrated to give 0.26 g of an yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 5%] to afford 75.5 mg (55%) of alcohol 50 and 43.3 mg (32%) of allylic addition by-product, alcohol 51. For spectroscopic data see below. Zincate derivative: t-BuLi (0.90 mL, 1.5 mmol, 1.7 M pentane) was added dropwise to 320 (3 mL) at —78 °C. A solution of vinyl bromide B (0.16 g, 0.74 mmol) in Et20 (2 mL) was added dropwise to the t-BuLi solution. After stirring for 10 minutes, ZnMez (0.38 mL, 0.75 mmol, 2.0 M toluene) was added. After stirring for an additional 15 minutes, valeraldehyde (0.054 mL, 0.50 mmol) was added dropwise. After 126 stirring for 1 hour at -78 °C, the reaction was allowed to warm to room temperature over 30 minutes and then stirred for an additional 15 minutes. The reaction was quenched by the addition of a saturated aqueous NH4CI solution (1 mL). 320 (15 mL) was added and the phases separated. The organic phase was washed with water (3 mL x 2). The combined aqueous phases were extracted with 320 (5 mL). The combined organics were washed with brine (5 mL), dried over MgSOa, filtered and concentrated to give 0.17 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 5%] to afford 0.10 g (90%) of alcohol 50 as a yellow oil. 1H NMR (300 MHz, CDCla) 8 = 5.22 (dd, J: 3.02, 1.37 Hz, 1 H), 5.10 (t, J = 1.10 Hz, 1 H), 4.15 (t, J: 6.59 Hz, 1 H), 3.08 (ABq t, J: 19.79, 1.37, 1 H), 2.96 (ABq t, J: 19.79, 1.37 Hz, 1 H), 1.55 (m, 2 H), 1.30 (m, 4 H), 0.88 (t, J: 7.14 Hz, 3 H), 0.15 (s, 9 H); 13C NMR (75 MHz, CDCI3) 8 = 146.1, 112.3, 87.7, 74.9, 34.8, 27.8, 22.6, 14.0, 0.04. Preparation of alcohol (52) [fragment AIB coupling]: El Et ms OTBS o 5‘ TMS ores o 5' OH (in 526 Vinyl bromide B (0.12 g, 0.59 mmol) and MgBrzoEtZO (0.30 g, 1.2 mmol) were dissolved in THF (6 mL) and cooled to -78 °C. t-BuLi (0.70 mL, 1.2 mmol, 1.7 M pentane) was added dropwise over ~5 minutes. After stirring for an additional 10 minutes, a solution of aldehyde 33 (38 mg, 0.12 mmol) in THF (1 mL) was added dropwise. After stirring for 1.5 hours at —78 °C, the reaction was 127 allowed to warm to room temperature over 30 minutes and then stirred an additional 15 minutes. The reaction was quenched by the addition of a saturated aqueous NH4CI solution (1 mL). 320 was added, and the phases separated. The aqueous phase was extracted with 820 (2x). The combined organics were washed with brine, dried over Na2SO4, filtered and concentrated to give 76 mg of a crude yellow oil. The crude residue was purified by flash chromatography on silica gel [Hex/EtOAc 5%] to afford Zinca te derivative: t-BuLi (0.86 mL, 1.5 mmol, 1.7 M pentane) was added dropwise to Et20 (3 mL) at -78 °C. A solution of vinyl bromide B (0.16 g, 0.74 mmol) in Eth (2 mL) was added dropwise to the t-BuLi solution. After stirring for 10 minutes, ZnMez (0.50 mL, 1.0 mmol, 2.0 M toluene) was added and the reaction stirred for an additional 15 minutes. In a separate flask, to a —78 °C solution of aldehyde 33 (0.16 g, 0.487 mmol) in Eth (3 mL) was added ZnMez (0.25 mL, 0.50 mmol, 2.0 M pentane) and the mixture stirred for 15 minutes. The zincate derivative of fragment B was quickly transferred via cannula to the pre-complexed aldehyde solution. After stirring for 1 hour at -78 °C, the reaction was allowed to warm to room temperature over 60 minutes and was then quenched by the addition of a saturated aqueous NH4CI solution (1.5 mL). EtQO (15 mL) was added and the phases separated. The organic phase was washed with water (3 mL x 2). The combined aqueous phases were extracted with 320 (5 mL). The combined organics were washed with brine (5 mL), dried over MgSO4, filtered and 128 concentrated to give 0.16 g of a yellow oil. Purification by flash chromatography on silica gel [Hex/EtOAc 5%] afforded several products. 52a: 1H NMR (300 MHz, CDCI3) 6 = 5.45 (s, 1 H), 5.30 (s, 1 H), 5.25 (s, 1 H), 5.12 (s, 1 H), 4.55 (dd, J: 9.07, 5.77 Hz, 1 H), 4.19 (dd, J: 7.59, 5.77 Hz, 1 H), 4.17 (d, J = 4.67 Hz, 1 H), 3.99 (app t, J: 5.22 / 4.95 Hz, 1 H), 3.50 (dd, J = 9.07, 7.69 Hz, 1 H), 3.10 (ABq, J= 19.50 Hz, 1 H), 2.98 (ABq, J= 19.76 Hz, 1 H), 2.78 (d, J: 5.77 Hz, 1 H), 1.68 (m, 4 H), 0.90 (m, 6 H), 0.89 (s, 9 H), 0.14 (s, 9 H), 0.05 (s, 3 H), 0.02 (s, 3 H); 13C NMR (75 MHz, CDCla) 8 = 146.2, 142.5, 114.4, 114.2, 113.6, 103.3, 77.4, 76.3, 75.3, 75.1, 70.8, 38.6, 29.9, 29.6, 25.8, 18.2, 8.1 (2), 0.03, -4.5, -5.1; HRMS (El) m/z 466.2922 [M*; calcd for C25H4604Si2, 466.2935]. 526: 1H NMR (300 MHz, CDCla) 6 = 5.49 (s, 1 H), 5.31 (d, J: 1.37 Hz, 1 H), 5.25 (m, 1 H), 5.15 (s, 1 H), 4.56 (dd, J: 9.07, 5.77 Hz, 1 H), 4.20 — 4.14 (m, 2 H), 4.07 (dd, J: 3.85, 6.59 Hz, 1 H), 3.59 (dd, J: 9.0, 7.69 Hz, 1 H), 3.12 (ABq, J = 19.78 Hz, 1 H), 2.97 (ABq, J = 19.50 Hz, 1 H), 2.46 (d, J = 3.85 Hz, 1 H), 1.65 (m, 4 H), 0.90 (m, 6 H), 0.86 (s, 9 H), 0.14 (s, 9 H), 0.04 (s, 3 H), 0.01 (s, 3 H). Preparation of PMB-ether (54): El OPMB g 5‘ PhS ’ 54 To a stirred suspension of NaH (0.23 g, 8.9 mmol, 95% in mineral oil) in DMSO (10 mL) was added dropwise a solution of alcohol 29 (1.84 g, 5.96 mmol) in THF (30 mL) at room temperature. After stirring for 25 minutes, p-methoxybenzyl chloride (1.30 mL, 9.54 mmol) was added. After stirring for 3.5 129 hours, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (4 mL). The reaction mixture was diluted with Etzo (80 mL) and water (5 mL) and the phases were separated. The organic phase was washed with brine (5 mL x 2), dried over M9804, filtered and concentrated to give 3.53 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5% -+ 10%] afforded 2.36 g (93%) of PMB-ether 54 as a clear oil. IR (neat, 4 cm"): v = 2973,2936.2660,1613,1566,1514,1461,1464,1439,1302,1246,1173,1060, 1059, 1036, 920, 622, 741, 693; [6339 +103.4° (c 0.71, CHCla); 1H NMR (300 MHz, CDCI3) 8 = 7.15 - 7.30 (m, 7 H), 6.84 (d, J: 8.79 Hz, 2 H), 5.54 (app t, J: 1.10 Hz, 1 H), 5.29 (s, 1 H), 4.53 (dd, J: 8.79, 5.49 H, 1 H), 4.51 (ABq, J= 11.26 Hz, 1 H), 4.26 (ABq, J= 11.26 Hz, 1 H), 4.07 (dd, J: 7.69, 6.04 Hz, 1 H), 3.96 (dd, J: 7.69, 5.49 Hz, 1 H), 3.76 (s, 3 H), 3.51 (dd, J: 9.07, 7.69 Hz, 1 H), 3.11 (dABq, J = 7.97, 13.46 Hz, 1 H), 2.99 (dABq, J= 5.22, 13.46 Hz, 1 H), 1.65 (m, 4 H), 0.91 (t, J: 7.42 Hz, 3 H), 0.90 (t, J: 7.42 Hz, 3 H); 13c NMR (75 MHz, CDCI3) 6 = 159.2, 145.1, 136.2, 129.9, 129.6, 129.5, 126.9, 126.1, 115.1, 113.7, 112.7, 76.5, 75.3, 70.6, 70.5, 55.3, 69.0, 29.8, 29.5, 8.2, 8.1; HRMS (Cl) m/z 429.2096 [(M + H)‘; calcd for 025H3304S, 429.2100]. Preparation of sulfoxide (55): El ol OPMB g 5‘ P .7 To a solution of phenyl sulfide 54 (2.34 g, 5.46 mmol) in CHZCIz (120 mL) at -78 °C was added dropwise (~20 minutes) a solution of m-CPBA (1.13 g, 6.55 mmol) in CH20I2 (25 mL). After stirring for 10 minutes the reaction was judged 130 complete by TLC. The reaction was quenched by the addition of 1M NaOH (6.5 mL). The reaction mixture was allowed to warm to room temperature and the phases were separated. The organic phase was washed with 1 M NaOH (6.5 mL), water (10 mL x 2) and brine (10 mL). The organics were dried over MgSO4, filtered and concentrated to give 2.43 g (100%) of a cloudy oil, which was used without further purification. Preparation of ot-acetoxy sulfide (56): El PMB (aka ”18% 0A0 Trifluroacetic anhydride (1.15 mL, 2.69 mmol) was dissolved in acetic anhydride (5.5 mL) and the solution stirred at room temperature for 8 hours. A solution of crude sulfoxide 55 (2.43 g, 5.46 mmol) in Et20/Ac20 (5 mL) was added and after a few minutes 2,6-Iutidine (1.27 mL, 10.9 mmol) was added. After stirring for 12 hours at room temperature, the reaction was concentrated under high vacuum. CH20I2 (40 mL) was added and the solution was then washed with a saturated aqueous NaHCOa solution (5 mL x 3) and brine (5 mL). The combined organics were dried over MgSO4, filtered and concentrated to give 3.24 g of a dark red oil. Purification by flash chromatography on silica gel [hexanes/EtOAc, 10%] afforded 2.03 g (76%) of ot-acetoxy sulfide 56 as a thick yellow oil. 1H NMR (300 MHz, CDCI3) 6 = 7.41 (m, 4 H), 7.25 (m, 10 H), 6.64 (d, J = 8.79 Hz, 4 H), 6.23 (d, J: 5.49 Hz, 1 H), 6.13 (d, J: 5.77 Hz, 1 H), 5.64 (s, 1 H), 5.57 (app t, J: 1.10 Hz, 1 H), 5.44 (s, 1 H), 5.34 (s, 1 H), 4.57 (m, 4 H), 4.30 (d, J: 11.26 Hz, 1 H), 4.28 (ABq, J= 11.54 Hz, 1 H), 3.99 - 4.13 (m, 4 H), 3.79 131 (s, 6 H), 3.57 (dd, J = 9.07, 7.97 Hz, 1 H), 3.50 (dd, J: 9.07, 7.97 Hz, 1 H), 2.20 (s, 3 H), 1.96 (s, 3 H), 1.65 (m, 8 H), 0.90 (m, 12 H) Reduction of ot-acetoxy sulfide to give alcohol (57): El OPMB Q—Sfe‘ 57 To a cold (0 °C) solution of ot-acetoxy sulfide 56 (2.0 g, 4.1 mmol) in THF H0 (55 mL) was added dropwise (~20 minutes) Super-Hydride‘D (13.6 mL, 13.6 mmol, 1.0 M THF). The ice bath was removed and the reaction stirred at room temperature for 45 minutes. The reaction was quenched by the addition of a saturated aqueous NH4CI solution (12 mL) and glycerol (4.1 mL, 0.3 mUmmol). The reaction mixture was diluted with Et20 (80 mL) and stirred for several hours. The phases were separated, and the organic phase was washed with brine (5 mL x 2), dried over MgSO4, filtered and concentrated to give a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25%] afforded 1.2 g (87%) of alcohol 57 as a yellow oil. IR (neat, 4 cm“): v = 3466, 2973, 2940, 2881, 1613, 1515, 1465, 1249, 1174, 1077, 1036, 920, 823; [6339 +504 (0 0.84, CHCla); 1H NMR (300 MHz, CDCI3) 6 = 7.23 (d, J: 6.79 Hz, 2 H), 6.66 (d, J: 8.79 Hz, 2 H), 5.53 (app t, J: 1.10 Hz, 1 H), 5.35 (s, 1 H), 4.55 (ABq, J= 11.26 Hz, 1 H), 4.53 (dd, J: 8.24, 6.32 Hz, 1 H), 4.26 (ABq, J= 11.26 Hz, 1 H), 4.12 (dd, J: 7.69, 6.32 Hz, 1 H), 3.98 (dd, J: 7.14, 4.40 Hz, 1 H), 3.76 (s, 3 H), 3.52 (m, 3 H), 1.68 (m, 4 H), 0.93 (t, J: 7.42 Hz, 3 H), 0.89 (t, J: 7.42 Hz, 3 H); ‘30 NMR (75 MHZ, CDCI3) 6 = 159.3, 143.6, 129.8, 129.6, 115.4, 113.9, 113.0, 80.3, 132 75.9, 70.4, 70.1, 65.5, 55.2, 29.8, 29.3, 8.2, 8.1; HRMS (Cl) m/z 203.1280 [(M + H)"; calcd for C10H1904, 203.1283]. Oxidation of alcohol (57) to give aldehyde (58): El PMB Q E‘ H .T o 58 To a stirred solution of the Dess-Martin periodinane (0.28 g, 0.65 mmol) in CH20I2 (10 mL) were added pyridine (0.053 mL, 0.653 mmol) and a solution of alcohol 57 (0.20 g, 0.59 mmol) in CHzClz (0.5 mL). The reaction stirred at room temperature until judged complete by TLC (~1 hour). The reaction was quenched by the addition of a saturated aqueous NaHCOal10% N62820:; (1 :1) solution (5 mL) and diluted with 320 (25mL). After stirring for 1 hour, the phases were separated. The organic phase was washed with water (2 mL), aqueous saturated CuSO4 solution (2 mL x 2), water (2 mL) and brine (2 mL). The organics were dried over NaZSO4, filtered and concentrated to give 0.18 g (90%) of aldehyde 56 as a yellow oil. (egg, +6.9° (c 0.96, CHCI3); 1H NMR (300 MHz, CDCI3) 6 = 9.52 (d, J: 1.65 Hz, 1 H), 7.25 (d, J: 8.79 Hz, 2 H), 6.66 (d, J: 6.79 Hz, 2 H), 5.61 (app t, J: 1.10 Hz, 1 H), 5.34 (d, J: 0.55 Hz, 1 H), 4.58 (ABq, J= 11.54 Hz, 1 H), 4.52 (dd, J: 6.79, 6.32 Hz, 1 H), 4.43 (ABq, J= 11.54 Hz, 1 H), 4.23 (s, 1 H), 4.05 (dd, J: 7.97, 6.32 Hz, 1 H), 3.79 (s, 3 H), 3.60 (dd, J: 9.07, 7.97 Hz, 1 H), 1.68 (m, 4 H), 0.93 (t, J: 7.42 Hz, 3 H), 0.89 (t, J: 7.42 Hz, 3 H); ”C NMR (75 MHz, CDCla) 6 = 199.1, 159.5, 140.4, 129.8, 128.8, 116.2, 113.9, 113.3, 83.9, 76.3, 70.9, 69.5, 55.3, 29.7, 29.2, 8.3, 8.0. 133 Preparation of alcohol (60) [fragment AIB coupling]: El El 3+0 gpMe / TMS Et+o 99MB 0 t / O\*n/\/CH3 6H 8H 60 81 t-BuLi (0.30 mL, 0.50 mmol, 1.7 M pentane) was added dropwise to Et20 (1 mL) at ~78 °C. A solution of vinyl bromide B (0.055 g, 0.25 mmol) in E120 (0.7 mL) was added dropwise (~7 minutes) to the t-BuLi solution. After stirring for 10 minutes, ZnMez (0.17 mL, 0.34 mmol, 2.0 M toluene) was added. In a separate flask, to a solution of aldehyde 58 (0.056 g, 0.167 mmol) in Et20 (1 mL) at ~78 °C was added ZnMez (0.09 mL, 0.167 mmol, 2.0 M toluene). After both solutions had stirred for 15 minutes at ~78 °C, the zinc reagent was quickly transferred via cannula to the pre-complexed aldehyde solution. After stirring for 1.5 hours at -78 °C, the reaction was allowed to warm to room temperature over 60 minutes and was then quenched by the addition of a saturated aqueous NH4CI solution (1 mL) dropwise. E120 (5 mL) was added, and the phases were separated. The organic phase was washed with water (1 mL x 2) and brine (1 mL). The combined aqueous phases were extracted with 320 (5 mL). The combined organics were washed with brine (3 mL), dried over MgSO4, filtered and concentrated to give a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10% —> 25%] afforded 32 mg (41 %) of alcohol 60 as a yellow oil. Grignard protocol: t-BuLi (3.8 mL, 6.56 mmol, 1.7 M pentane) was added dropwise to Et20 (15 mL) at ~78 °C. A solution of vinyl bromide B (0.70 g, 3.2 mmol) in 320 (6 134 mL) was added dropwise (~12 minutes) to the t-BuLi solution. After stirring for 10 minutes, MgBrzoEtZO (3.5 mL, 1.0 M EtZO/PhH (3:1), 3.5 mmol) was added and stirred at ~78 °C for 15 minutes and then at 0 °C for 10 minutes and then the reaction temperature lowered back to ~78 °C. In a separate flask, to a solution of aldehyde 58 (0.72 g, 2.15 mmol) in Et20/PhH (3:1) (2mL) at 0 °C was added MgBrzoEtZO (2.2 mL, 1.0 M EtZO/PhH (3:1), 2.2 mmol). The aldehyde solution was transferred via cannula to the Grignard solution. After stirring for 1 hour at -78 °C, the reaction was allowed to warm to 0 °C and stirred for 2 hours. The reaction was quenched by the addition of a saturated aqueous NH4CI solution (2 mL) and water (2 mL). 320 (2 mL) was added, and the phases were separated. The organic phase was washed with brine (2x). The combined aqueous phases were extracted with Et20. The combined organics were dried over MgSO4, filtered and concentrated to give 1.2 g of a yellow oil, which was purified by flash chromatography on silica gel [hexanes/EtOAc 10%, 1% EtaN] to give 0.65 g (64%) of alcohol 60 as a yellow oil. IR (neat, 4 cm"): v = 3546, 2969, 2663, 2178,1613,1515,1465,1303,1250,1173,1078,1036,918,843,761; [ofigg +55.1° (c 0.69, CHCI3); 1H NMR (300 MHz, cool.) 6 = 7.21 (cl, J= 8.52 Hz, 2 H), 6.65 (d, J: 6.52 Hz, 2 H), 5.63 (t, J: 1.37 Hz, 1 H), 5.35 (s, 1 H), 5.33 (d, J = 1.37 Hz, 1 H), 5.13 (s, 1 H), 4.55 (ABq, J= 10.99 Hz, 1 H), 4.51 (dd, J: 9.07, 6.04 Hz, 1 H), 4.22 (ABq, J= 10.99 Hz, 1 H), 4.15 (dd, J: 7.69, 6.04 Hz, 1 H), 4.08 (m, 1 H), 3.84 (d, J: 6.04 Hz, 1 H), 3.79 (s, 3 H), 3.51 (dd, J: 9.07, 7.69 Hz, 1 H), 3.07 (ABq, J= 19.78 Hz, 1 H), 2.66 (d, J: 3.57 Hz, 1 H), 2.66 (ABq, J= 19.78 Hz, 1 H), 1.65 (m, 4 H), 0.94 (t, J: 7.42 Hz, 3 H), 0.90 (t, J: 7.42 Hz, 3 135 H), 0.14 (s, 9 H); “‘0 NMR (75 MHz, 00%) 6 = 159.4, 143.5, 141.9, 129.7, 129.5, 116.3, 115.2, 113.9, 112.8, 103.3, 67.7, 81.3, 76.2, 75.3, 70.6, 70.5, 55.2, 29.9, 29.5, 23.2, 8.2, 6.1, 0.01; HRMS (El) m/z 443.2246 [(M - Et)“; calcd for 025H35055i, 443.2254]. By-product alcohol 61: 1H NMR (300 MHz, CDCla) 6 = 7.22 (d, J: 6.79 Hz, 2 H), 6.86 (d, J: 8.79 Hz, 2 H), 5.66 (t, J: 1.37 Hz, 1 H), 5.31 (d, J: 1.10 Hz, 1 H), 4.56 (m, 1 H), 4.55 (ABq, J= 10.99 Hz, 1 H), 4.22 (ABq, J= 10.99 Hz, 1 H), 4.11 (dd, J: 7.69, 6.04 Hz, 1 H), 3.79 (s, 3 H), 3.60 (m, 2 H), 3.49 (dd, J: 9.07, 7.69 Hz, 1 H), 2.76 (br s, -OH), 1.66 (m, 4 H), 1.06 (d, J: 6.04 Hz, 3 H), 0.93 (t, J: 7.42 Hz, 3 H), 0.91 (t, J: 7.42 Hz, 3 H); “’0 NMR (75 MHz, 00013) 6 = 159.4, 143.7, 129.7, 117.4, 113.9, 112.7, 66.1, 74.9, 70.9, 70.3, 68.9, 55.3, 29.9, 29.6, 16.3, 6.2, 6.1. TMS-deprotection to give alkyne (62): OH m H 82 To a cold (0 °C) solution of TMS-alkyne 50 (0.127 g, 0.566 mmol) in THF (5 mL) was added dropwise (~5 minutes) an acetic acid buffered TBAF solution (1.05:1) (0.60 mL, 0.60 mmol, 1.0 M THF). After stirring for 2 hours, 320 (12 mL) was added and then the reaction was quenched by the addition of water (2 mL). The phases were separated, and the organic phase was washed with brine (1 mL x 2), dried over MgSO4, filtered and concentrated to give 0.12 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 78 mg (90%) of alkyne 62 as a yellow oil. 1H NMR (300 MHz, CDCI3) 8 136 = 0.66 (t, J: 7.14 Hz, 3 H), 1.30 (m, 4 H), 1.55 (m, 2 H), 2.13 (t, J: 2.75 Hz, 1 H), 2.92 (thBq, J = 2.75, 1.37, 19.50 Hz, 1 H), 3.06 (thBq, J = 2.75, 1.10, 19.50 Hz, 1 H), 4.15 (t, J: 6.59 Hz, 1 H), 5.12 (m, 1 H), 5.25 (dt, J= 1.65, 1.37 Hz, 1 H); ‘30 NMR (75 MHz, CDCI3) 6 = 145.9, 112.3, 61.3, 74.8, 71.0, 34.7, 27.7, 22.5, 21.0, 14.0. Preparation of PMB-ether (64): OPMB Q TMS 64 To a solution of alcohol 50 (0.14 g, 0.624 mmol) and p-CHaOPhCHzOC(NH)CCI3 (0.70 g, 2.49 mmol)78 in cyclohexane/CHZCIZ (1 :1) (4 mL) was added CSA (15 mg, 0.062mmol). The reaction vessel was immersed into a preheated oil bath (~40 °C). After stirring for 3 hours, more CSA (20 mg) was added. After stirring for a total of 12 hours, the reaction mixture was allowed to cool to room temperature, diluted with ether (15 mL), and quenched by the addition of a saturated aqueous NaHCOa solution (2 mL). The phases were separated, and the organic phase was washed with a saturated aqueous NaHCOa solution (2 mL x 2) and brine (3 mL), dried over MgSO4, filtered and concentrated to give a white-yellow solid. Hexanes were added to the residue which was stirred for 30 minutes and then filtered. The solid was washed several times with hexanes. The filtrate was concentrated to give 0.43 g of an yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5%] afforded 0.11 g (51%) of PMB-ether 64 as a clear oil. 1H NMR (300 MHz, 00013) 6 = 0.17 (s, 9 H), 0.85 (t, J: 6.87 Hz, 3 H), 1.30 (m, 4 H), 1.55 (m, 2 H), 2.93 (ABq, J= 20.33 Hz, 1 H), 137 3.03 (ABq, J= 20.05 Hz, 1 H), 3.78 (m, 1 H), 3.79 (s, 3 H), 4.16 (ABq, J= 11.26 Hz, 1 H), 4.42 (ABq, J: 11.54 Hz, 1 H), 5.11 (d, J: 1.37 Hz, 1 H), 5.41 (d, J: 1.65 Hz, 1 H), 6.85 (d, J: 8.52 Hz, 2 H), 7.22 (d, J: 8.52 Hz, 2 H); 13c NMR (75 MHz, 00013) 6 = 159.1, 143.3, 130.60, 129.4, 114.4, 113.7, 103.9, 87.7, 81.9, 69.9, 55.2, 33.6, 26.0, 22.5, 21.4, 14.0, 0.09. Preparation of alkyne (65): OPMB \\ H 35 To a solution of TMS-alkyne 64 (0.11 g, 0.32 mmol) in THF (3 mL) was added dropwise an acetic acid buffered TBAF solution (0.39 mL, 0.39 mmol, 1.0 M THF). After stirring for 3.5 hours at room temperature, EtZO (10 mL) was added and then quenched with the addition of a saturated aqueous NaHCOs solution (0.4 mL) and water (0.4 mL). The phases were separated, and the organic phase washed with brine (0.5 mL), dried over MgSO4, filtered and concentrated to give 93 mg of a yellow oil. Purification by flash chromatography on silica gel [Hexanes/EtOAc 5%] afforded 79 mg (91%) of alkyne 65 as a clear oil. 1H NMR (300 MHz, CDCla) 8 = 0.85 (t, J: 6.87 Hz, 3 H), 1.28 (m, 4 H), 1.60 (m, 2 H), 2.16 (t, J: 2.75 Hz, 1 H), 2.89 (app qABq, J= 1.92, 20.05 Hz, 1 H), 3.01 (thBq, J= 2.75, 1.37, 20.05 Hz, 1 H), 3.78 (m, 1 H), 3.78 (s, 3 H), 4.17 (ABq,J=11.26 Hz, 1 H), 4.42 (ABq, J= 11.54 Hz, 1 H), 5.12 (d, J: 1.10 Hz, 1 H), 5.43 (app q, J= 1.65 Hz, 1 H), 6.85 (d, J: 9.07 Hz, 2 H), 7.23 (d, J: 9.07 Hz, 2 H). 13c NMR (75 MHz, 00013) 6 = 159.1, 143.0, 130.5, 129.4, 114.6, 113.7, 81.9, 81.3, 71.2, 69.7, 55.3, 33.5, 27.9, 22.5, 19.8, 14.0. 138 Hydrostannylation of alkyne (65) to give vinyl stannane (66): OPMB OPMB SOB (Ph3P)2PdCl2 (1 mg, 0.002 mmol) and Red-Slim” (0.22 g, 0.463 mmol, 2.1 mmol/9) were added to 320 (1.5 mL) and followed by the addition of a solution of alkyne 62 (0.042 g, 0.15 mmol) in 320 (0.5 mL), BuasnF (0.057 g, 0.19 mmol) and a few crystals of TBAF. After stirring for 1.5 hours at room temperature, more Red-Sil (70 mg) was added and the reaction stirred for an additional 2 hours. The reaction was filtered through a pad of Celite on a glass frit. The residual Red-Sil was washed several times with Et20. The filtrate was concentrated to give 86 mg of a brown cloudy oil. From 1H NMR, the crude vinyl stannane 66 was a mixture of E- and internal isomers (1 .5:1). 1H NMR (300 MHz, CDCI3) 8 = 7.24 (d, J = 8.79 Hz, 2 H), 7.23 (d, J = 8.79 Hz, 2 H), 6.85 (d, J = 8.79 Hz, 4 H), 5.95 (m, 2 H), 5.70 (m, 1 H), 5.29 (m, 1 H), 5.05 (s, 1 H), 5.01 (s, 1 H), 4.96 (s, 1 H), 4.84 (d, J: 1.65 Hz, 1 H), 4.46 (ABq, J= 10.99 Hz, 1 H), 4.43 (ABq,J=10.99 Hz, 1 H), 4.16 (ABq, J= 11.54 Hz, 1 H), 4.16 (ABq, J= 11.54 Hz, 1 H), 3.78 (s, 6 H), 3.70 (m, 2 H), 3.0 ~ 2.70 (m, 4 H), 1.60 — 0.80 (3 series of m, 72 H). Preparation of diene (67) ~ Model Stille coupling: 0 OPMB 05‘ / / 67 To a solution of (MeCN)2PdCI2 (2 mg, 0.008 mmol) in DMF (1 mL) were added a solution of (Z)-B-iodo ethyl ester 49 (37 mg, 0.15 mmol) in DMF (0.1 mL) 139 and a solution of crude vinyl stannane 66 (86 mg, 0.15 mmol) in DMF (0.1 mL). After stirring for 12 hours at room temperature, the reaction was diluted with ether (10 mL) and then washed with brine (1 mL x 3), a saturated aqueous KF solution (1 mL x 2) and brine (1 mL). The organics were dried over MgSO4, filtered and concentrated to give 0.16 g of a yellow oil, which was purified by flash chromatography on silica gel [hexanes/EtOAc 5%] to give 61.2 mg of a diene 67 contaminated with residual vinyl iodide 49 as a yellow oil after two columns. Preparation of terminal alkyne (68): a El 2L. .. W 811 To a solution of TMS-alkyne 60 (0.14 g, 0.30 mmol) in THF (3 mL) was added an acetic acid buffered TBAF (1.05:1) solution (0.36 mL, 1.0 M THF, 0.36 mmol) dropwise. After stirring for 3.5 hours at room temperature, the reaction was diluted with ether (10 mL) and then quenched by the addition of a saturated aqueous NaHCOa solution (0.4 mL) and water (0.4 mL). The phases were separated, and the organic phase was washed with brine (0.5 mL), dried over M9804, filtered and concentrated to give 0.11 g (93%) of alkyne 68 as a yellow oil. 1H NMR (300 MHz, 00013) 6 = 7.21 (d, J: 6.24 Hz, 2 H), 6.86 (d, J: 8.24 Hz, 2 H), 5.64 (s, 1 H), 5.35 (s, 2 H), 5.14 (s, 1 H), 4.56 (ABq, J=10.44 Hz, 1 H), 4.51 (dd, J: 9.34, 6.04 Hz, 1 H), 4.22 (ABq, J= 10.99 Hz, 1 H), 4.14 (dd, J: 7.69, 6.04 Hz, 1 H), 4.08 (d, J: 6.59 Hz, 1 H), 3.83 (d, J: 6.59 Hz, 1 H), 3.79 (s, 3 H), 3.51 (dd, J: 9.34, 7.69 Hz, 1 H), 3.03 (ABq, J= 19.78 Hz, 1 H), 2.86 (ABq, 140 J= 19.78 Hz, 1 H), 2.10 (t, J: 2.75 Hz, 1 H), 1.64 (m, 4 H), 0.92 (m, 6 H); ”C NMR (75 MHz, CDCI3) 6 = 159.4, 143.5, 141.6, 129.7, 129.4, 116.4, 115.3, 113.6, 112.6, 61 .3, 60.9, 76.3, 75.3, 71.2, 70.6, 70.4, 55.2, 29.6, 29.4, 21.7, 8.2, 8.1. Preparation of vinyl stannane (69): El 3+0 SnBua Red-Sil (0.53 g, 2.1 mmol/9, 1.1 mmol) and (PhaP)2PdCl2 (2 mg, 0.003 mmol) were dissolved in 320 (2 mL) and followed by the addition of a solution of crude alkyne 68 (0.11 g, 0.28 mmol) in 320 (1 mL), BuasnF (0.11 g, 0.36 mmol), and a few crystals of TBAF. After stirring for 4 hours at room temperature, the reaction mixture was filtered through a glass frit filter with a pad of Celite. The Red-Sil was washed several times with 320. The filtrate was concentrated to give 0.16 g of a yellow oil, which was purified by flash chromatography on silica gel [Hexanes/EtOAc 10%] to give 27 mg (14%) of pure E-vinyl stannane 69, 51 mg (27%) as a mixture of regioisomers (E-stannane major) and 44 mg (23%) of a regio-mixture (internal major). E-isomer: 1H NMR (300 MHz, CDCIa) 6 = 7.22 (d, J: 8.79 Hz, 2 H), 6.86 (d, J: 8.79 Hz, 2 H), 5.90 (m, 2 H), 5.62 (s, 1 H), 5.33 (s, 1 H), 5.09 (s, 1 H), 4.96 (d, J = 1.10 Hz, 1 H), 4.56 (ABq, J= 10.44 Hz, 1 H), 4.51 (dd, J: 8.79, 6.04 Hz, 1 H), 4.23 (ABq, J= 10.99 Hz, 1 H), 4.14 (dd, J: 7.69, 6.04 Hz, 1 H), 3.98 (dd, J: 141 6.04, 3.85 Hz, 1 H), 3.62 (d, J: 6.04 Hz, 1 H), 3.79 (s, 3 H), 3.50 (dd, J: 8.79, 7.69 Hz, 1 H), 2.92 (dABq, J = 4.40, 19.32 Hz, 1 H), 2.86 (d, J = 3.85 Hz, -OH), 2.70 (dABq, J= 4.40, 19.23 Hz, 1 H), 1.65 (m, 4 H), 1.46 (m, 6 H), 1.26 (m, 12 H), 0.87 (m, 15 H); "’0 NMR (75 MHz, CDCI3) 6 = 159.4, 146.0, 145.7, 143.9, 130.9, 129.7, 129.6, 116.1, 114.1, 113.6, 112.7, 81.5, 76.6, 75.2, 70.8, 70.4, 55.3, 40.7, 29.9, 29.5, 29.1, 27.3, 13.7, 9.4, 6.2, 8.1. internal isomer: 1H NMR (300 MHz, CD03) 6 = 7.22 (d, J= 8.79 Hz, 2 H), 6.85 (d, J: 8.24 Hz, 2 H), 5.60 (s, 1 H), 5.59 (m, 1 H), 5.33 (s, 1 H), 5.21 (m, 1 H), 5.15 (s, 1 H), 4.90 (s, 1 H), 4.55 (ABq, J= 10.99 Hz, 1 H), 4.52 (dd, J: 7.69, 6.59 Hz, 1 H), 4.23 (ABq, J= 10.99 Hz, 1 H), 4.17 (dd, J: 7.69, 6.59 Hz, 1 H), 3.93 (t, J: 5.49 / 4.40 Hz, 1 H), 3.82 (d, J: 4.94 Hz, 1 H), 3.79 (s, 3 H), 3.52 (dd, J = 6.79, 7.69 Hz, 1 H), 3.01 (ABq, J= 15.93 Hz, 1 H), 2.71 (ABq, J= 15.93 Hz, 1 H), 2.66 (d, J: 4.94 Hz, -OH), 1.66 (m, 4 H), 1.44 (m, 6 H), 1.26 (m, 12 H), 0.87 (m, 15 H); ‘30 NMR (75 MHz, 00013) 6 = 159.3, 152.4, 146.3, 144.2, 129.7, 129.6, 127.4, 115.7, 114.2, 113.8, 112.7, 60.7, 75.8, 75.2, 70.8, 70.3, 55.2, 44.0, 29.9, 29.5, 29.0, 27.4, 13.7, 9.6, 6.2, 8.1. Preparation of diene (70) “ABD”: Stille Cross-coupling: A solution of szdbaa (1 mg, 0.001 mmol) and AsPha (1.3 mg, 0.0044 mmol) in NMP (0.2 mL) was stirred at room temperature for 10 minutes and then 142 a solution of (Z)-B-iodo ethyl ester 49 (0.013 g, 0.055 mmol) in NMP (0.2 mL) was added. The reaction vessel was immersed into a preheated oil bath (~50 °C) and a solution of vinyl stannane 69 (0.038 g, 0.055 mmol) in NMP (0.2 mL) was immediately added. After stirring for 16 hours at 50 °C, the reaction was allowed to cool to room temperature and then diluted with 320 (6 mL). The organic phase was washed with water (0.2 mL), brine (0.2 mL), a saturated aqueous KF solution (0.2 mL x 2) and brine (0.2 mL). The organics were dried over MgSO4, filtered and concentrated to give 95 mg of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 15 mg (52%) of diene 70 as a yellow oil. For spectroscopic data see below. Liebeskind’s Cross-coupling: To a solution of (Z)-|3-iodo ethyl ester 49 (0.017 g, 0.072 mmol) in NMP (0.2 mL) was added copper (I) thiophene-2-carboxylate (CuTc) (0.010 g, 0.054 mmol). To this suspension was added a solution of vinyl stannane 69 (0.026 g, 0.036 mmol) in NMP (0.2 mL). After stirring for 30 minutes, the reaction was diluted with Et20 (6 mL) and filtered through a bed of Celite. The green filter cake was washed with Et20 (3 mL). The clear filtrate was washed with water (0.6 mL x 3), a saturated aqueous KF solution (0.5 mL x 2), and brine (0.6 mL). The organics were dried over MgSO4, filtered and concentrated to give 48 mg of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 10 mg (56%) of diene 70 as a yellow oil. 1H NMR (300 MHz, CDCIa) 8 = 7.56 (d, J = 15.93 Hz, 1 H), 7.22 (d, J = 8.79 Hz, 2 H), 6.86 (d, J = 8.79 Hz, 2 H), 6.06 (dt, J= 15.36, 7.14 Hz, 1 H), 5.62 (s, 1 H), 5.61 (s, 1 H), 5.34 143 (s, 1 H), 5.10 (s, 1 H), 4.95 (s, 1 H), 4.55 (ABq, J=10.99 Hz, 1 H), 4.51 (dd, J: 8.79, 6.04 Hz, 1 H), 4.23 (ABq, J= 10.99 Hz, 1 H), 4.13 (m, 3 H), 4.0 (dd, J: 6.04, 3.30 Hz, 1 H), 3.83 (d, J: 6.59 Hz, 1 H), 3.79 (s, 3 H), 3.50 (dd, J: 8.79, 7.69 Hz, 1 H), 2.99 (dABq, J= 6.59, 16.46 Hz, 1 H), 2.90 (d, J: 3.30 Hz, -OH), 2.79 (dABq, J= 7.69, 16.48 Hz, 1 H), 1.95 (d, J: 1.10 Hz, 3 H), 1.65 (m, 4 H), 1.25 (t, J: 7.14 Hz, 3 H), 0.94 (t, J: 7.69 Hz, 3 H), 0.89 (t, J: 7.69 Hz, 3 H); ”C NMR (75 MHz, CDCI3) 6 = 166.2, 159.4, 150.6, 145.6, 143.7, 135.6, 129.8, 129.5, 116.5, 116.4, 114.9, 113.9, 112.8, 81.5, 76.8, 75.1, 70.7, 70.4, 59.7, 55.3, 35.6, 29.9, 29.5, 21.1, 14.3, 6.2, 8.1; HRMS (Cl) m/z 515.3001 [(M + H)+; calcd for 030H4307, 515.3009]. Preparation of PMB-ether (72): To a solution alcohol 60 (0.095 g, 0.201 mmol) and p—CH30PhCH200(NH)CCI378 (0.23 g, 0.80 mmol) in cyclohexane/CH20I2 (3:1) (2 mL) was added CSA (5 mg, 0.02 mmol). The reaction vessel was immersed into a preheated oil bath (~40 °C). After stirring for 3 hours at 40 °C, more CSA (11 mg) was added. After stirring for a total of 12 hours, the reaction mixture was allowed to cool to room temperature, diluted with 320 (15 mL), and quenched by the addition of a saturated aqueous NaHCOa solution (1 mL). The phases were separated, and the organic phase was washed with a saturated aqueous NaHCOa solution (2 mL x 2) and brine (3 mL), dried over M9804, filtered and concentrated to give a 144 white-yellow solid. Hexanes were added to the residue, stirred for 30 minutes and then filtered. The solid was washed several times with hexanes. The filtrate was concentrated to give 0.21 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 49 mg (41%) of PMB-ether 72 as an oil. 1H NMR (300 MHz, CDCI3) 6 = 7.27 (d, J: 8.79 Hz, 2 H), 7.22 (d, J = 8.24 Hz, 2 H), 6.87 (d, J = 8.24 Hz, 2 H), 6.83 (d, J = 8.79 Hz, 2 H), 5.54 (s, 1 H), 5.45 (s, 1 H), 5.31 (s, 1 H), 5.16 (s, 1 H), 4.53 (ABq, J= 10.99 Hz, 1 H), 4.46 (ABq, J= 11.54 Hz, 1 H), 4.45 (m, 1 H), 4.27 (ABq, J = 10.99 Hz, 1 H), 4.23 (ABq, J = 11.54 Hz, 1 H), 3.99 (dd, J = 7.69, 6.04 Hz, 1 H), 3.95 (d, J = 5.49 Hz, 1 H), 3.84 (d, J: 6.04 Hz, 1 H), 3.79 (s, 3 H), 3.78 (s, 3 H), 3.41 (dd, J: 8.79, 7.69 Hz, 1 H), 3.04 (ABq, J= 20.33 Hz, 1 H), 2.94 (ABq, J= 20.33 Hz, 1 H), 1.64 (m, 4 H), 0.91 (t, J: 7.14 Hz, 3 H), 0.87 (t, J: 7.14 Hz, 3 H), 0.17 (s, 9 H); ”C NMR (75 MHz, CDCI3) 8 = 159.1, 159.0, 143.7, 140.8, 130.4, 130.2, 130.1, 129.7, 115.9, 115.3, 113.8(2), 112.6, 103.6, 87.6, 83.0, 81.2, 75.5, 71.4, 70.7, 70.6, 55.2, 29.8, 29.5, 23.6, 8.1, 0.08. Preparation of terminal alkyne (73): To a solution TMS-alkyne 72 (0.049 g, 0.083 mmol) in THF (0.8 mL) was added an acetic acid buffered TBAF (1.05:1) solution (0.10 mL, 1.0 M THF, 0.10 mmol) dropwise. After stirring for 5 hours at room temperature, the reaction was diluted with Et20 (5 mL) and then quenched by the addition of a saturated 145 aqueous NaHCOa solution (0.1 mL) and water (0.1 mL). The phases were separated, and the organic phase was washed with brine (0.2 mL), dried over MgSO4, filtered and concentrated to give 40 mg (93%) of crude alkyne 73 as a yellow oil. Preparation of 1-bromo—alkyne (74): To a solution of crude alkyne 73 (0.040 g, 0.077 mmol) in acetone (0.2 mL) were added NBS (0.0164 9, 0.0924 mmol) and AgNOa (1.3 mg, 0.0077 mmol). The flask was wrapped with aluminum foil and stirred at room temperature for one hour. The reaction was quenched by the addition of water (0.2 mL), diluted with Et20 (1.5 mL) and the phases were separated. The organic phase was washed with brine, dried over MgSO4, filtered and concentrated to give 37 mg of crude 1-bromo-alkyne 74 as a yellow oil. Preparation of TBS-ether (76): To a solution of alcohol 60 (0.45 g, 0.95 mmol) in CHZCIZ (4.5 mL) was added 2,6-Iutidine (0.22 mL, 1.9 mmol) and TBSOTf (0.33 mL, 1.4 mmol). After stirring for 60 minutes, the reaction was quenched with water (1 mL) and a 146 saturated aqueous NH4CI solution (1 mL). The reaction was diluted with EtzO (50 mL), and the phases were separated. The organic phase was washed with brine (2 mL x 2), a saturated aqueous CuS04 solution (2 mL x 2) and brine (2 mL). The combined aqueous phases were extracted with Et20 (3 mL). The combined organics were dried over MgSO4, filtered and concentrated to give 0.59 g of a yellow oil, which was purified by flash chromatography on silica gel [hexanes/EtOAc 5% --> 10%] to give 0.50 g (89%) of TBS-ether 76 as a yellow oil. IR (neat, 4 cm"): v = 2957, 2929, 2657, 2176, 1613, 1514, 1464, 1258, 1173, 1079, 1040, 920, 642, 777,760, 699; [aE§9+16.9° (c 0.625, CHCI3); 1H NMR (300 MHz, CDCIa) 6 = 7.21 (d, J: 8.52 Hz, 2 H), 6.63 (d, J: 8.52 Hz, 2 H), 5.52 (s, 1 H), 5.24 (s, 2 H), 5.07 (s, 1 H), 4.52 (app d, J: 9.07 Hz, 1 H), 4.50 (ABq, J= 11.26 Hz, 1 H), 4.28 (d, J: 5.49 Hz, 1 H), 4.24 (ABq, J= 11.26 Hz, 1 H), 4.05 (dd, J: 7.42, 6.04 Hz, 1 H), 3.76 (s, 3 H), 3.63 (d, J: 5.49 Hz, 1 H), 3.43 (dd, J: 9.07, 7.69 Hz, 1 H), 3.07 (ABq, J= 19.78 Hz, 1 H), 2.90 (ABq, J= 19.78 Hz, 1 H), 1.65 (m, 4 H), 0.92 (t, J: 7.42 Hz, 3 H), 0.88 (t, J: 7.42 Hz, 3 H), 0.64 (s, 9 H), 0.14 (s, 9 H), -0.01 (s, 3 H), -0.02 (s, 3 H); ”C NMR (75 MHz, 00013) 6 = 143.4, 130.3, 129.3, 114.2, 113.6, 104.1, 100.3, 62.0, 70.6, 55.3, 30.1, 29.7, 25.8, 25.7, 23.9, 16.2, 6.2, 8.1, 0.11, -2.9, -4.9; HRMS (CI) m/z 587.3573 [(M + H)*; calcd for C33H55058i2, 587.3588]. Hydrolysis of isopentylidene acetal (76) to give diol (77) and trial (78): 147 77 p-toluenesulfonic acid monohydrate: ‘ To a solution of isopentylidene acetal 76 (0.12 g, 0.20 mmol) in MeOH (2 mL) was added p-toluenesulfonic acid monohydrate (PTSA) (4 mg, 0.02 mmol). After stirring at room temperature for 12 hours, the reaction was quenched by the addition of a saturated aqueous NaHCOa solution (0.4 mL). The reaction mixture was diluted with 320 (10 mL) and water (2 mL) and then the phases were separated. The organic phase was washed with brine (0.5 mL x 2). The combined aqueous phases were extracted with Et20 (3 mL). The combined organics were dried over MgSO4, filtered and concentrated to give 63 mg of a yellow oil, which was purified by flash chromatography on silica gel [hexanes/EtOAc 10% -—> 25%] to give 6.7 mg of desired diol 77 (6%) as a yellow oil, 19 mg (23%) of triol 78 via acetonide hydrolysis and loss of the TBS moiety, and 16.4 mg (17%) of alcohol 60 via loss of the TBS group only. For spectroscopic data see below. 10-camphorsulfonic acid: To a solution of isopentylidene acetal 76 (0.46 g, 0.78 mmol) in MeOH/ CH2C|2 (2:1) (9 mL) was added 10-camphorsulfonic acid (CSA) (0.018 g, 0.078 mmol). The reaction was immersed into a preheated oil bath (40 °C). After stirring for 6 hours, additional CSA (18 mg) was added. A second portion of CSA (18 mg) was made after 24 hours. After stirring for a total of 31 hours, the reaction was allowed to cool to room temperature and was then neutralized with 146 EtaN (0.5 mL). The reaction mixture was then concentrated to give 0.45 g of a yellow oil, which was purified by flash chromatography on silica gel [hexanes/ EtOAc 25% —> 50%, 0.5% MeOH] to give 0.145 g (46%) of triol 78 and 92 mg (25%) of alcohol 60 as clear oils. diol 77: IR (neat, 4 cm"): v = 3417, 2957, 2931,2858, 2177, 1613, 1515, 1471, 1464, 1303, 1250, 1174, 1084, 1037, 915, 842, 777,760; 1H NMR (300 MHz, CDCI3) 8 = 7.21 (d, J = 8.79 Hz, 2 H), 6.84 (d, J = 8.79 Hz, 2 H), 5.30 (s, 1 H), 5.26 (d, J = 1.65 Hz, 1 H), 5.21 (s, 1 H), 5.07 (s, 1 H), 4.49 (ABq, J = 11.54 Hz, 1 H), 4.43 (d, J: 6.04 Hz, 1 H), 4.34 (ABq, J= 11.54 Hz, 1 H), 4.19 (m, 1 H), 3.83 (d, J: 6.04 Hz, 1 H), 3.79 (m, 4 H), 3.56 (m, 1 H), 3.09 (ABq, J= 19.78 Hz, 1 H), 2.94 (ABq, J= 19.78 Hz, 1 H), 0.86 (s, 9 H), 0.14 (s, 9 H), 0.03 (s, 3 H), 0.01 (s, 3 H); 13C NMR (75 MHz, CDCI3) 8 = 159.2, 144.6, 143.1, 129.4, 115.2, 114.6, 113.7, 103.9, 84.4, 77.2, 75.2, 72.1, 71 .2, 65.4, 55.3, 25.8, 23.5, 18.2, 0.08, -5.0; HRMS (Cl) m/z 519.2948 [(M + H)‘; calcd for C23H4705$i2, 519.2962]. triol 78: IR (neat, 4 cm"): v = 3397, 2956, 2929, 2176, 1612, 1515, 1457, 1420, 1303, 1251, 1174, 1036, 922, 645, 760; [111339 +56.9° (c 0.50, CHCla); 1H NMR (300 MHz, 00013) 6 = 7.20 ( d, J: 8.52 Hz, 2H), 6.85 (d, J: 6.52 Hz, 2 H), 5.45 (s, 1 H), 5.34 (s, 2 H), 5.16 (s, 1 H), 4.53 (ABq, J=10.99 Hz, 1 H), 4.25 (ABq, J: 10.99 Hz, 1 H), 4.22 - 4.18 (m, 2 H), 3.66 (d, J: 5.77 Hz, 1 H), 3.78 (s, 3 H), 3.69 (dd, J: 11.26, 3.57 Hz, 1 H), 3.57 (dd, J: 11.26, 7.14 Hz, 1 H), 3.06 (ABq, J= 19.78 Hz, 1 H), 2.90 (ABq, J= 19.78 Hz, 1 H), 0.14 (s, 9 H); “0 NMR (75 MHZ, CDCla) 8 = 159.5, 145.2, 142.2, 129.7, 129.2, 116.6, 114.9, 113.9, 103.4, 149 87.8, 82.0, 76.4, 72.4, 70.8, 65.8, 55.3, 23.3, 0.01; HRMS (CI) m/z 405.2079 [(M + H)*; calcd for szHaaOsSi, 405.2097]. Hydrolysis of isopentylidene acetal (60) to give trial (78): El El 5‘25 I,“ To a solution of isopentylidene acetal 60 (0.38 g, 0.80 mmol) in MeOH was added PTSA (0.015 g, 0.080 mmol). The reaction vessel was immersed into a preheated oil bath (~40 °C). After 11.5 hours, additional PTSA (15 mg) was added, as well as THF (1 mL). After stirring for 24 hours, CSA (19 mg) and THF (2 mL) was added. After stirring an additional 4.5 hours, the reaction was neutralized by the addition of EtaN (0.5 mL) and then concentrated to give 0.49 g of a yellow oil. CH2CI2 (5 mL) was added to residue. The residue was washed with brine (0.5 mL), water (0.5 mL), a saturated aqueous NaHCOa solution (0.5 mL), and brine (0.5 mL). The combined aqueous phases were extracted with EtzO. The organics were dried over MgSO4, filtered and concentrated to give 0.38 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25% --> 50%, 0.5% MeOH] to give 0.16 g (50%) of desired triol 78 as a yellow oil, 65 mg (17%) of recovered alcohol 60 and small amounts of by-products 79 and 80. by-product 79: IR (neat, 4 cm"): v = 3426, 2971, 2944, 2884, 2180, 1464, 1250, 1199, 1175, 1076, 1034, 928, 843, 760; 1H NMR (300 MHz, CDCIa) 8 = 5.38 (s, 1 H), 5.34 (s, 1 H), 5.30 (s, 1 H), 5.18 (s, 1 H), 4.33 (s, 2 H), 4.27 (m, 1 H), 3.69 (m, 150 2 H), 3.14 (ABq, J= 19.23 Hz, 1 H), 3.0 (ABq, J= 19.23 Hz, 1 H), 2.94 (s, 1 H), 2.33 (s, 1 H), 1.75 - 1.62 (m, 4 H), 0.93 (t, J: 7.69 Hz, 3 H), 0.92 (t, J: 7.69 Hz, 3 H), 0.14 (s, 9 H); 13c NMR (75 MHz, CDCI3) 6 = 143.6, 139.1, 116.5, 116.1, 112.9, 88.0, 63.1, 80.8, 76.3, 71.9, 65.4, 30.2, 30.1, 22.3, 8.1, -0.06; LRMS (Cl) m/z 353 [(M + H)*; calcd for C(9H3304Si, 353]. by-product 80: IR (neat, 4 cm"): v = 2957, 2926, 2655, 2160, 1746, 1464, 1250, 1198, 1173, 1080, 1059, 1034, 922, 643, 760; 1H NMR (300 MHz, CDCla) 6 = 5.53 (s, 1 H), 5.40 (d, J: 1.10 Hz, 1 H), 5.34 (s, 1 H), 5.22 (s, 1 H), 4.53 (dd, J: 8.79, 6.04 Hz, 1 H), 4.26 (d, J: 8.79 Hz, 1 H), 4.22 (d, J: 9.07 Hz, 1 H), 4.17 (dd, J: 7.69, 6.04 Hz, 1 H), 3.49 (dd, J: 8.79, 7. 69 Hz, 1 H), 3.15 (ABq, J= 19.50 Hz, 1 H), 3.01 (ABq, J=19.78 Hz, 1 H), 1.70 (m, 6 H), 0.90 (m, 12 H), 0.14 (s, 9 H); “’0 NMR (75 MHz, 00013) 6 = 143.4, 139.7, 116.6, 113.4, 112.8, 112.6, 67.9, 63.7, 79.3, 77.2, 75.5, 70.9, 30.1, 29.9, 29.6, 29.4, 22.7, 22.3, 8.1, 6.0, - 0.02; LRMS (Cl) m/z 421 [(M + H)*; calcd for C24H41O4Si, 421]. Preparation of p-methoxybenzylidene acetal (81): 81 To a solution of triol 78 (0.16 g, 0.40 mmol) in DMF (1 mL) were added PTSA (4 mg, 0.02 mmol) and p-MeOCeH4CH(OMe)2 (0.080 mL, 0.47 mmol). The reaction was immersed into a preheated oil bath (~55 °C) and stirred for 2.5 hours. The reaction was neutralized with EtaN (0.1 mL). The resulting mixture was diluted with EtOAc (10 mL). The phases were separated, and the organic phase washed with brine (1 mL x 2) and H20 (1 mL). The combined aqueous 151 phases were extracted with EtOAc. The organics dried over MgSO4, filtered and concentrated to give 0.49 g of a yellow oil, which was purified by flash chromatography on silica gel [hexanes/EtOAc 25%] to give 0.16 g (78%) of a diastereomeric mixture of p-methoxybenzylidene acetal 81 as an oil. Preparation of TBS-ether (82): To a solution of alcohol 81 (0.16 g, 0.31 mmol) in CH20l2 (1.5 mL) were added 2,6-lutidine (0.071 mL, 0.61 mmol) and TBSOTf (0.10 mL, 0.46 mmol). After stirring at room temperature for 1 hour, the reaction was quenched by the addition of water (0.3 mL) and a saturated aqueous NH4CI solution (0.3 mL). The mixture was diluted with ether (15 mL) and then the phases were separated. The organic phase was washed with brine (0.6 mL), a saturated aqueous CuSO4 solution (0.6 mL x 2) and brine (0.6 mL). The combined aqueous phases were extracted with Et20 (1 mL). The combined organics were dried over MgSO4, filtered and concentrated to give 0.26 g of a yellow oil, which was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 0.11 g (56%) of TBS-ether 82 as a clear oil. Reduction of benzylidene acetal (82) to give PMB-ether (83): OPMB OPMB TMS OH 9% / OTBS OTBS TMS 152 To a solution of p-methoxybenzylidene acetal 82 (0.11 g, 0.17 mmol) in CHgClg (1 mL) at -78 °C was added DIBAL-H (0.51 mL, 1.0 M hexanes, 0.51 mmol) dropwise. After stirring for 1 hour at ~78 °C, the reaction was gradually allowed to warm to room temperature and stirred overnight (~20 hours). The reaction was quenched by the addition of EtOAc (0.2 mL) and a aqueous solution of Rochelle’s salt (1 mL). The mixture solidified and therefore, CH2Cl2 was added. After stirring overnight, the reaction mixture was separated. The organic phase was washed with Rochelle’s salt (2x). The combined aqueous phases were extracted with CH2C|2 (3x). The combined organics were dried over MgSO4, filtered and concentrated to give 82 mg of an yellow oil, which was purified by flash chromatography on silica gel [hexanes/EtOAc 25%] to give 49 mg (50%) of a mixture of PMB-ethers 83. Preparation of diol (84): OH QPMB Ho ’ SPh To a solution of isopentylidene acetal 54 (1.68 g, 3.92 mmol) were added CSA (0.091 g, 0.39 mmol) and water (0.25 mL). The reaction was immersed into a preheated oil bath (40 °C). After stirring for 12 hours, the reaction was allowed to cool to room temperature and was then neutralized with EtaN (0.17 mL). The reaction solution was concentrated and 320 (20 mL) was added to the residue. The resulting solution was washed with brine (1 mL x 2), dried over MgSO4, filtered and concentrated to give 1.48 g of a thick yellow oil, which was purified by flash chromatography on silica gel [hexanes/EtOAc 50%, 1% MeOH] to give 1.26 153 g (89%) of diol 84 as a clear oil. IR (neat, 4 cm"): v = 3409, 2932, 2870, 2836, 1613,1566,1514,1462,1464,1439,1302,1246,1175,1060,1034,926,622, 741; [11E]9 +73.1° (c 0.73, CHCla); 1H NMR (300 MHz, CDCI3) 6 = 7.30 - 7.13 (m, 7 H), 6.84 (d, J: 8.79 Hz, 2 H), 5.36 (s, 1 H), 5.26 (s, 1 H), 4.49 (ABq, J= 10.99 Hz, 1 H), 4.32 (ABq, J= 10.99 Hz, 1 H), 4.26 (m, 1 H), 3.99 (t, J: 7.14 Hz, 1 H), 3.78 (s, 3 H), 3.67 (m, 1 H), 3.57 (m, 1 H), 3.25 (dABq, J= 7.14, 13.19 Hz, 1 H), 3.11 (dABq, J= 6.04, 13.19 Hz, 1 H), 2.69 (m, -OH), 2.23 (m, -OH); "’0 NMR (75 MHz, cock.) 6 =159.3, 146.0, 135.9, 129.6, 129.5, 126.9, 126.2, 116.4, 113.6, 79.9, 76.6, 72.0, 70.8, 65.8, 55.3, 38.5; HRMS (Cl) m/2361.1462 [(M + H)*; calcd for C20H2504S, 361 .1474]. Preparation of mono-protected 1,2-diol (85): OH QPMB (n-Pr)38IO ’ SPh To a solution of diol 84 (0.420 g, 1.17 mmol) in CH2C|2 (12 mL) was added imidazole (0.16 g, 2.3 mmol), DMAP (0.014 g, 0.12 mmol), and tri-n-propylsilyl chloride (0.26 mL, 1.2 mmol). After stirring for 2 hours at room temperature, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (4 mL). Ether (25 mL) was added, and the phases were separated. The organic phase was washed with brine (3 mL x 2), dried over M9304, filtered and concentrated to give 0.60 g of a clear oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 0.39 g (65%) of mono-silylated 85 and 0.17 g (22%) of the fully disilylated diol as clear oils. IR (neat, 4 cm"): v = 3480, 2955, 2926, 2869, 1612, 1586, 1514, 1481, 1462, 1439, 154 1302, 1246, 1209, 1173, 1090, 1067, 1038, 924, 822,739; [6339+65.0° (c 0.785, CHCI3); 1H NMR (300 MHz, 0006) 6 = 7.30 - 7.10 (m, 7 H), 6.83 (d, J: 8.79 Hz, 2 H), 5.42 (s, 1 H), 5.33 (s, 1 H), 4.52 (ABq, J= 10.99 Hz, 1 H), 4.27 (ABq, J= 11.54 Hz, 1 H), 4.17 (m, 1 H), 3.97 (dd, J: 7.69, 4.94 Hz, 1 H), 3.78 (s, 3 H), 3.60 (dd, J: 9.69, 3.30 Hz, 1 H), 3.44 (dd, J: 10.44, 8.24 Hz, 1 H), 3.16 (dd, J: 13.19, 7.69 Hz, 1 H), 3.07 (dd, J: 13.19, 5.49 Hz, 1 H), 2.75 (d, J: 2.75 Hz, - OH), 1.32 (m, 6 H), 0.93 (t, J: 7.14 Hz, 9 H), 0.57 (m, 6 H); “’0 NMR (75 MHz, cock.) 6 =159.2, 146.4, 136.5, 129.9,129.5,129.2, 128.8, 125.9, 115.5, 113.7, 78.7, 71.6, 70.4, 66.8, 55.2, 39.2, 18.3, 16.7, 16.2; HRMS (Cl) 111/25172607 [(M + H)*; calcd for C29H4504SSI, 517.2808]. Preparation of mono-protected 1,2-diol (87): OH QPMB TIPSO ’ SPh 87 To a solution of diol 84 (1.41 g, 3.91 mmol) in CH2C|2 (40 ml.) were added imidazole (0.53 g, 7.8 mmol), DMAP (0.048 g, 0.391 mmol), and triisopropylsilyl chloride (0.88 mL, 4.1 mmol). After stirring for 24 hours at room temperature, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (5 mL). Et20 (80 mL) was added, and the phases were separated. The organic phase was washed with brine (5 mL x 2). The combined aqueous phases were extracted with 320 (5 mL x 2). The combined organics were dried over MgSO4, filtered and concentrated to give 2.34 g of a clear oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 25%] to give 1.84 g (91%) of mono-silylated 87. IR (neat, 4 cm"): v = 3474, 2944, 2889, 1613, 155 1566. 1514, 1464, 1439, 1365, 1302, 1246, 1173, 109/, 1038, 920, 664, 820, 739; [3123, +64.1° (c 0.695, CHCIa); 1H NMR (300 MHz, cool.) 6 = 7.30 - 7.11 (m, 7 H), 6.62 (d, J: 8.79 Hz, 2 H), 5.44 (s, 1 H), 5.33 (s, 1 H), 4.52 (ABq, J= 10.99 Hz, 1 H), 4.28 (A80, J= 10.99 Hz, 1 H), 4.20 (m, 1 H), 3.97 (dd, J: 5.49, 7.69 Hz, 1 H), 3.78 (s, 3 H), 3.70 (dd, J: 3.85, 9.69 Hz, 1 H), 3.55 (dd, J: 8.24, 9.89 Hz, 1 H), 3.16 (dABq, J= 7.69, 13.19 Hz, 1 H), 3.08 (dABq, J= 5.49, 13.19 Hz, 1 H), 2.64 (d, J: 2.20 Hz, -OH), 1.03 (m, 21 H); 13c NMR (75 MHz, cool.) 6 =159.2, 146.3, 136.5, 129.9, 129.5, 128.8, 125.9, 115.5, 113.7, 78.6, 77.2, 71.6. 70.4, 67.5, 55.2, 39.3, 17.9, 11.6; HRMS (Cl) m/2517.2805 [(M + H)+; calcd for ngH4504SSi, 517.2808]. Preparation of fully protected trial (89): OPMB QPMB TIPSO ’ SPh To a cold (0 °C) solution of alcohol 87 (0.46 g, 0.89 mmol) in THF (8 mL) was added NaHMDS (1.34 mL, 1.0 M THF, 1.34 mmol) dropwise. The ice bath was removed and the reaction stirred at room temperature for 30 minutes, after which time DMSO (2.5 mL) and PMBCI (0.20 mL, 1.4 mmol) were added. After stirring for 1.5 hours, the reaction was quenched with a saturated aqueous NH4C| solution (1 mL) and diluted with 320 (20 mL) and water (0.5 mL). The phases were separated, and the organic phase was washed with brine (1 mL x 2), dried over MgSO4, filtered and concentrated to give 0.85 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 5% —> 10%] to give 0.45 g (79 %) of fully protected triol 89 as a clear oil. IR (neat, 4 156 cm"): v = 2940,2865, 1613, 1514, 1464, 1302, 1246, 1173, 1066, 1038, 664; [01 239 +71 .9° (c 0.705, CHCla); 1H NMR (300 MHz, CDCIa) 6 = 7.30 - 7.10 (m, 9 H), 6.85 (d, J: 8.79 Hz, 2 H), 6.84 (d, J: 8.79 Hz, 2 H), 5.45 (s, 1 H), 5.44 (s, 1 H), 4.59 (ABq, J= 11.54 Hz, 1 H), 4.53 (ABq, J= 11.54 Hz, 1 H), 4.43, (ABq, J= 11.54 Hz, 1 H), 4.29 (ABq, J= 11.54 Hz, 1 H), 3.98 (t, J: 6.59 Hz, 1 H), 3.89 (dd, J = 4.40, 6.59 Hz, 1 H), 3.82 — 3.74 (m, 7 H), 3.65 (dd, J = 4.40, 10.44 Hz, 1 H), 3.11 (d, J: 6.59 Hz, 2 H), 1.03 (m, 21 H); “*0 NMR (75 MHz, CDCI3) 6 = 159.1, 145.7, 136.7, 130.5, 1302,1294, 129.3,129.2,128.8, 125.6, 115.4, 113.7, 60.0, 77.9, 70.6, 70.5, 66.8, 55.2, 39.6, 17.9, 11.9; HRMS (CI) m/z 637.3365 [(M + H)*; calcd for C37H530588i, 637.3383]. Preparation of alcohol (90): 02MB gPMe HO SPh To a solution of TIPS-silyl ether 89 (0.126 g, 0.198 mmol) in THF (2 mL) was added TBAF (0.24 mL, 1.0 M THF, 0.24 mmol) dropwise. After stirring for 20 minutes, the reaction was diluted with 320 (5 mL) and water (0.2 mL). The phases were separated, and the organic phase was washed with brine (0.2 mL x 2). The combined organics were dried over MgSO4, filtered and concentrated to give 0.139 of a yellow oil. The cmde residue was purified by flash chromatography on silica gel [hexanes/EtOAc 25% —> 50%] to give 80 mg (84%) of alcohol 90 as a yellow oil. IR (neat, 4 cm"): v = 3409, 2932, 2670, 2636, 1613, 1586, 1514, 1482, 1464, 1439, 1302, 1248, 1175, 1080, 1034, 928, 822, 741; 1H NMR (300 MHz, CDCI3) 8 = 7.21 (d, J: 8.79 Hz, 2 H), 7.20 (d, J: 8.79 157 Hz, 2 H), 7.20 (m, 4 H), 6.65 (d, J: 8.79 Hz, 2 H), 6.84 (m, 1 H), 6.83 (d, J: 8.79 Hz, 2 H), 5.48 (s, 1 H), 5.44 (s, 1 H), 4.57 (ABq, J= 11.54 Hz, 1 H), 4.51 (ABq, J = 11.54 Hz, 1 H), 4.30 (ABq, J= 11.54 Hz, 1 H), 4.28 (ABq, J= 11.54 Hz, 1 H), 3.93 (m, 2 H), 3.76 (s, 6 H), 3.50 (m, 2 H), 3.18 (dABq, J= 7.69, 13.19 Hz, 1 H), 3.07 (dABq, J = 5.49, 13.19 Hz, 1 H). Preparation of aldehyde (91): OPMBQPMB H SH) 0 91 To a stirred solution of Dess-Martin periodinane (0.074 g, 0.18 mmol) in CHgCIz (3 mL) were added pyridine (0.014 mL, 0.18 mmol) and a solution of alcohol 90 (0.080 g, 0.17 mmol) in CHzclz (0.5 mL). After stirring for 50 minutes at room temperature, the reaction was quenched by the addition of a saturated aqueous NaHCOa /10% aqueous Nazsan (1 :1) solution (2 mL) and diluted with EtZO (10 mL). After stirring for 30 minutes, the phases were separated. The organic phase was washed with water (0.4 mL), a saturated aqueous CUSO4 solution (0.4 mL x 2), water (0.4 mL) and brine (0.5 mL), dried over Na2304, filtered and concentrated to give 77 mg (97%) of crude aldehyde 91 as a yellow oil. 1H NMR (300 MHz, CDCI3) 6 = 9.52 (cl, J= 1.65 Hz, 1 H), 7.19 (m, 6 H), 6.85 (d, J: 8.24 Hz, 2 H), 6.84 (m, 1 H), 6.83 (d, J: 8.24 Hz, 2 H), 5.47 (s, 1 H), 5.43 (s, 1 H), 4.58 (ABq, J= 10.99 Hz, 1 H), 4.45 (ABq, J= 11.54 Hz, 1 H), 4.36 (A80, J= 11.54 Hz, 1 H), 4.22 (d, J: 1.65 Hz, 1 H), 4.14 (ABq, J= 10.99 Hz, 1 H), 3.97 (dd, J = 7.14, 6.04 Hz, 1 H), 3.78 (s, 6 H), 3.22 (dABq, J= 7.14, 13.73 Hz, 1 H), 3.11 (dABq, J= 6.04, 13.73 Hz, 1 H); 13c NMR (75 MHz, 00013) 6 = 199.2, 158 159.5, 159.3, 141.7, 136.2, 129.7, 129.6, 129.1, 128.9, 128.8, 125.9, 120.5, 113.9, 113.7, 84.2, 78.9, 71.0, 70.7, 55.3, 38.2. Preparation of ot-acetoxy sulfide (93): OPMB QPMB TIPSO ’ SPh OAc 93 To a solution of phenyl sulfide 89 (0.43 g, 0.68 mmol) in CHzclz (13 mL) at ~78 °C was added dropwise (~8 minutes) a solution of m-CPBA (0.14 g, 0.81 mmol) in CHch2 (4 mL). After stirring for 10 minutes (until judged complete by TLC), the reaction was quenched with 1 M NaOH (0.81 mL) and then allowed to warm to room temperature. The phases were separated, and the organic phase was washed with 1 M NaOH (0.81 mL x 2) and brine (1 mL), dried over MgSO4, filtered and concentrated to give 0.43 g (100%) of crude sulfoxide 92 as a clear oil. Pummerer rearrangement: Trifluoroacetic anhydride (0.14 mL, 1.0 mmol) was dissolved in acetic anhydride (0.7 mL) and the solution stirred at room temperature for 7.5 hours. A solution of crude sulfoxide 92 (0.43 g, 0.68 mmol) in A020 (0.7 mL) was added and after a few minutes 2,6-lutidine (0.16 mL, 1.4 mmol) was added. After stirring for 12 hours at room temperature, the reaction mixture was concentrated under high vacuum. CH2CI2 (15 mL) was added to the residue and the resultant solution was then washed with a saturated aqueous NaH003 solution (1.5 mL x 2) and brine (2 mL). The combined organics were dried over MgSOa, filtered and concentrated to give 0.47 g of a dark red oil. The crude residue was purified by 159 flash chromatography on silica gel [hexanes/EtOAc, 10 %] to give 0.28 g (60 %) of ot-acetoxy sulfide 93 as a yellow oil. IR (neat, 4 cm"): v = 2942, 2867, 1750, 1613, 1514, 1464, 1370, 1302, 1246, 1219, 1173, 1090, 1036, 884, 821, 745; 1H NMR (300 MHz, CDCI3) 8 = 7.41 (m, 4 H), 7.23 (m, 14 H), 6.82 (m, 8 H), 6.34 (d, J: 3.85 Hz, 1 H), 6.22 (d, J: 3.85 Hz, 1 H), 5.61 (s, 1 H), 5.56 (s, 1 H), 5.52 (s, 1 H), 5.50 (s, 1 H), 4.63 - 4.49 (m, 4 H), 4.29 - 4.41 (m, 4 H), 4.22 (d, J = 3.30 Hz, 1 H), 4.11 (d, J: 3.30 Hz, 1 H), 3.96 (t, J = 5.49 Hz, 1 H), 3.91 (dd, J=4.40, 6.59 Hz, 1 H), 3.79 ~ 3.64 (m, 16 H), 1.96 (s, 3 H), 1.94 (s, 3 H), 1.01 (m, 42 H); 13C NMR (75 MHz, CDCI3) 8 = 169.5, 169.4, 159.2, 159.1, 158.9, 142.8, 142.4, 132.9, 132.7, 130.8, 130.6, 129.8, 129.5, 129.2 (2), 129.1, 128.9, 127.9, 127.8, 117.4, 116.3, 113.7, 113.6, 113.5, 83.5, 81.5, 80.5, 80.4, 79.1, 78.9, 70.9, 70.7, 70.6, 67.2, 66.9, 55.2, 20.9, 20.8, 18.0, 17.9, 11.8; HRMS (CI) m/z712.3697 [(M + NH); calcd for 039H5307SSIN, 712.3703]. Preparation of alcohol (94): OPMB QPMB Tipso\/'\‘(’-\/0H 94 To a cold (0 °C) solution of a-acetoxy sulfide 93 (0.28 g, 0.43 mmol) in THF (5 mL) was added dropwise (~4 minutes) Super-Hydride” (1.4 mL, 1.0 M THF, 1.4 mmol). The ice bath was removed. After stirring at room temperature for 30 minutes, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (2.2 mL) and glycerol (0.66 mL, 0.3 mL/mmol) and diluted with 320 (20 mL). After stirring for several hours, the phases were separated. The organic phase was washed with brine (2 mL x 2), dried over 160 MgSO4, filtered and concentrated to give 0.45 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10% a 25%] to give 0.18 g (82%) of alcohol 94 as a yellow oil. IR (neat, 4 cm"): v = 3453,2944,2667,1613,1514,1464,1302,1246,1173,1094,1067,1036.664, 622; [d]§§9 +64.9° (c 0.5625, CHCIa); 1H NMR (300 MHz, CDCIa) 6 = 7.23 (m, 4 H), 6.84 (m, 4 H), 5.46 (s, 1 H), 5.44 (s, 1 H), 4.56 (ABq, J= 11.54 Hz, 1 H), 4.55 (ABq, J= 10.99 Hz, 1 H), 4.38 (ABq, J= 11.54 Hz, 1 H), 4.26 (ABq, J= 10.99 Hz, 1 H), 4.01 (dd, J: 4.40, 7.14 Hz, 1 H), 3.90 (t, J: 6.04 Hz, 1 H), 3.78 (m, 7 H), 3.68 (dd, J = 5.49, 10.44 Hz, 1 H), 3.62 - 3.46 (m, 2 H), 2.40 (dd, J: 4.40, 8.79, -OH), 1.02 (m, 21 H); 13c NMR (75 MHz, 00013) 6 = 159.1, 144.0, 130.3, 130.2, 129.4, 129.2, 116.9, 113.9, 113.7, 60.3, 79.9, 70.7, 70.3, 66.3, 65.3, 55.3, 17.9, 11.9; HRMS (FAB, NBA + Kl) m/z 563.2636 [(M + K)“; calcd for Ca1H4305SiK, 583.2857]. Preparation of aldehyde (95): OPMB gm TIPSO ’ H To a stirred solution of Dess-Martin periodinane (0.24 g, 0.57 mmol) in CH2CI2 (10 mL) were added pyridine (0.050 mL, 0.57 mmol) and a solution of alcohol 94 (0.28 g, 0.51 mmol) in CHzclz (1.5 mL). After stirring for 3 hours at room temperature, the reaction was quenched by the addition of a saturated aqueous N3HCOa/1oo/o aqueous Nazszoa (1 :1) solution (8 mL) and diluted with hexanes (40 mL). After stirring for 60 minutes, the phases were separated. The organic phase was washed with water (1 mL), a saturated aqueous Cu804 161 solution (1 mL x 2), water (1 mL) and brine (1 mL), dried over Na2804, filtered and concentrated to give 0.26 g (91%) of aldehyde 95 as a yellow oil. IR (neat, 4 cm"): v = 2944, 2867, 1734, 1613, 1514, 1464, 1302, 1250, 1175, 1092, 1036, 884, 820; [111;];9 +21 .2° (c 0.865, CHCI3); 1H NMR (300 MHz, CDCIa) 6 = 9.46 (d, J = 1.47 Hz, 1 H), 7.23 (m, 4 H), 6.85 (d, J: 8.79 Hz, 2 H), 6.62 (d, J: 8.79 Hz, 2 H), 5.48 (s, 1 H), 5.46 (s, 1 H), 4.56 (ABq, J = 11.72 Hz, 1 H), 4.43 (ABq, J= 11.72 Hz, 1 H), 4.41 (ABq, J= 11.72, 1 H), 4.26 (s, 1 H), 4.24 (ABq, J= 11.72 Hz, 1 H), 3.94 (app t, J = 5.37 and 6.35 Hz, 1 H), 3.84 (dd, J = 6.84, 10.25 Hz, 1 H), 3.78 (s, 3 H), 3.77 (s, 3 H), 3.68 (dd, J: 5.37, 10.25 Hz, 1 H), 1.0 (m, 21 H); ”C NMR (75 MHz, CDCI3) 6 = 199.0, 159.1, 141.4, 130.2, 129.5, 129.4, 129.1, 119.4, 113.8, 113.6, 84.2, 80.9, 70.7, 70.6, 66.2, 55.2, 17.9, 11.8. Preparation of alcohol (96): TIPSO To a solution of crude aldehyde 95 (0.16 g, 0.30 mmol) in Et20/PhH (3:1) (4 mL) was added MgBrzoEtzo (0.31 mL, 1.0 M Et20/PhH (3:1), 0.31 mmol). The mixture was then cooled to 0 °C. Vinyl magnesium bromide (0.44 mL, 1.0 M THF, 0.44 mmol) was added dropwise. After stirring for 40 minutes at 0 °C, the reaction was quenched with a saturated aqueous NH4CI solution (0.5 mL) and water (0.1 mL). Et20 (1 mL) was added, and the phases separated. The organic phase was washed with water (0.2 mL) and brine (0.2 mL x 2), dried over MgSO4, filtered and concentrated to give 0.16 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10% 162 —+ 25%] to give 0.12 g (71 %) of vinyl addition alcohol 96 as a clear oil. IR (neat, 4 cm"): v : 3456, 2961, 2944, 2667, 1613, 1514, 1464, 1302, 1250, 1173, 1090, 1038, 922, 664, 601; [61339 +51 .3° (0 0.31, CHCIa); 1H NMR (300 MHz, CDCIa) 6 = 7.25 (d, J: 8.24 Hz, 2 H), 7.20 (d, J: 8.79 Hz, 2 H), 6.85 (d, J= 8.79 Hz, 2 H), 6.83 (d, J: 8.24 Hz, 2 H), 5.61 (ddd, J: 17.03, 10.99, 6.04 Hz, 1 H), 5.52 (s, 1 H), 5.43 (s, 1 H), 5.32 (dt, J: 17.03, 1.65 Hz, 1 H), 5.15 (dt, J: 10.44, 1.65 Hz, 1 H), 4.57 (ABq, J: 11.54 Hz, 1 H), 4.56 (ABq, J: 11.54 Hz, 1 H), 4.43 (ABq, J: 11.54 Hz, 1 H), 4.23 (ABq, J: 10.99 Hz, 1 H), 4.09 (m, 1 H), 393(1, J: 5.49 Hz, 1 H), 3.80 - 3.70 (m, 9 H), 2.89 (d, J: 3.85 Hz, -OH), 1.03 (m, 21 H); "‘0 NMR (75 MHz, CDCI3) 6 :1592, 159.0, 143.7, 136.7, 130.6, 129.9, 129.4, 129.2, 116.8, 113.8, 113.7, 62.3, 60.4, 74.4, 71.0, 70.4, 66.7, 55.3, 17.6, 11.9; HRMS (Cl) m/z 566.3716 [(M + NH.)+; calcd for 033H5405NSI, 588.3720]. Protection of alcohol (96) to give PMB-ether (97): OPMB OPMB TIPSO ' . \ 97 issue To a cold (0 °C) solution of alcohol 96 (0.16 g, 0.28 mmol) in THF (4 mL) was added NaHMDS (0.31 mL, 1.0 M THF, 0.31 mmol) dropwise. The ice bath was removed and the reaction stirred at room temperature for 20 minutes, after which time DMSO (1.3 mL) and PMBCI (0.053 mL, 0.392 mmol) were added. After stirring for 3 hours, the reaction was quenched with a saturated aqueous NH4CI solution (0.3 mL) and water (0.3 mL) and then diluted with EtZO (15 mL). The phases were separated, and the organic phase was washed with brine (0.3 mL x 2). The combined aqueous phase was extracted with Et20 (1 mL). The 163 combined organics were dried over MgSO4, filtered and concentrated to give 0.47 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 0.15 g (79 %) of fully protected tetra-0| 97 as a clear oil. IR (neat, 4 cm"): v = 2961, 2865, 1613, 1586, 1512, 1464, 1302, 1250, 1173, 1068, 1036, 922,882, 802; [01 (8)9 +40.3° (c 0.71, CHCIa); 1H NMR (300 MHz, CDCI3) 6 : 7.20 (d, J: 6.24 Hz, 6 H), 6.61 (m, 6 H), 5.62 (m, 1 H), 5.50 (s, 1 H), 5.39 (s, 1 H), 5.27 (d, J: 2.75 Hz, 1 H), 5.22 (s, 1 H), 4.50 (series ABq, 3 H), 4.30 (series ABq, 3 H), 3.91 (m, 3 H), 3.78 (s, 3 H), 3.77 (s, 3 H), 3.75 (s, 3 H), 3.63 (m, 2 H), 1.01 (s, 21 H); "’0 NMR (75 MHz, CDCIa) 6 : 156.9, 158.8, 143.9, 135.3, 131.2, 130.6, 130.5, 129.4, 129.3, 129.1, 118.3, 114.9, 113.7, 113.6, 113.5 (2), 81.9, 61.0, 80.3, 70.8, 70.5, 70.4, 67.2, 55.2, 16.0, 11.9; HRMS (CI) m/z 706.4292 [(M + NH.)+; calcd for CuHszOyNSi, 708.4296]. Deprotection of TIPS-silyl ether (97) to give alcohol (98): one QPMB HOW OPMB To a solution of TIPS-silyl ether 97 (0.15 g, 0.22 mmol) in THF (2 mL) was added TBAF (0.24 mL, 1.0 M THF, 0.24 mmol) dropwise. After stirring for 30 minutes, the reaction was diluted with 320 (12 mL) and water (0.4 mL). The phases were separated, and the organic phase was washed with brine (0.30 mL x 2), dried over MgSO4, filtered and concentrated to give 0.15 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/ EtOAc 25%] to give 0.11 g (94 %) of alcohol 98 as a clear oil. IR (neat, 4 cm"): v = 3445, 2961,2865, 1613, 1566. 1514. 1464. 1302.1248,1173. 1066, 1034. 164 926, 616; [61239 +62.2° (c 0.31, CHCI3); 1H NMR (300 MHz, 00013) 6 : 7.21 (m, 6 H), 6.84 (m, 6 H), 5.86 (ddd, J: 17.03, 10.44, 6.59 Hz, 1 H), 5.53 (s, 1 H), 5.46 (s, 1 H), 5.31 (m, 2 H), 4.56 (ABq, J: 11.54 Hz, 2 H), 4.50 (ABq, J: 10.99 Hz, 1 H), 4.34 (ABq, J= 11.54 Hz, 1 H), 4.33 (ABq, J= 12.09 Hz, 1 H), 4.12 (ABq, J= 10.99 Hz, 1 H), 4.00 (m, 2 H), 3.87 (d, J: 4.94 Hz, 1 H), 3.80 (s, 6 H), 3.77 (s, 3 H), 3.54 (m, 1 H), 3.39 (m, 1 H); 13c NMR (75 MHz, CDCI3) 6 : 159.1, 159.0, 142.7, 134.8, 1303,1302, 130.1, 129.5, 1294,1292, 118.8, 116.1, 113.7, 113.6, 61.6, 80.6, 79.6, 70.6, 70.4, 70.4, 64.9, 55.1. Preparation of aldehyde (99): To a stirred solution of Dess-Martin periodinane (0.096 g, 0.23 mmol) in CH20I2 (4 mL) were added pyridine (0.020 mL, 0.23 mmol) and a solution of alcohol 98 (0.11 g, 0.21 mmol) in CHZCIz (0.5 mL). After stirring for 2 hours at room temperature, the reaction was quenched with the addition of a saturated aqueous NaHCOa /10% aqueous NazS203 (1 :1) solution (4 mL) and diluted with Et20 (25 mL). After stirring for 2 hours, the phases were separated. The organic phase was washed with water (0.8 mL), a saturated aqueous Cu804 solution (0.8 mL x 2), water (0.8 mL) and brine (1.5 mL), dried over Na2804, filtered and concentrated to give 0.10 g (92 %) of aldehyde 99 as a yellow oil. IR (neat, 4 cm"): v : 2944,2867, 1734, 1613, 1514, 1464, 1302, 1250, 1175, 1092, 1036, 884, 620; [61,339 +10.6° (c 0.56, CHCIa); 1H NMR (300 MHz, cool.) 6 : 9.36 (d, J = 1.65 Hz, 1 H), 7.20 (m, 6 H), 6.83 (m, 6 H), 5.76 (m, 1 H), 5.51 (S, 1 H), 5.45 (s, 165 1 H), 5.27 (s, 1 H), 5.23 (dd, J: 6.59, 1.65 Hz, 1 H), 4.49 (ABq, J: 11.54 Hz, 2 H), 4.44 (ABq, J: 11.54 Hz, 1 H), 4.33 (ABq, J: 11.54 Hz, 1 H), 4.32 (m, 1 H), 4.31 (ABq, J: 10.99 Hz, 1 H), 4.23 (ABq, J: 11.54 Hz, 1 H), 4.0 (m, 2 H), 3.79 (s, 3 H), 3.78 (s, 3 H), 3.77 (s, 3 H); 13c NMR (75 MHz, CDCI3) 6 : 199.1, 159.3. 159.1, 159.0, 140.3, 134.7, 130.3, 130.1, 129.5, 129.4, 129.3, 116.7, 113.8, 113.6, 64.3, 81.6, 80.6, 71.1, 70.9, 70.5, 55.2. Preparation of alcohol (100): OPMB QPMB TMS W / : OPMB OH 100 t-BuLi (0.30 mL, 1.7 M pentane, 0.507 mmol) was added dropwise to a Et20 (1.5 mL) at ~78 °C. A solution of vinyl bromide B (0.55 g, 0.25 mmol) in Et20 (0.6 mL) was added dropwise to the t-BuLi solution. After stirring for 10 minutes, MgBrZ-EtzO (0.27 mL, 1.0 M Et20/PhH (3:1), 0.27 mmol) was added and stirred at ~78 °C for 15 minutes and then at 0 °C for 10 minutes and then lowered back to ~78 °C. In a separate flask, crude aldehyde 99 (90 mg, 0.17 mmol) was dissolved in an EtZO/benzene/CHzClz (3:1:1) solution (1.5 mL) and cooled to 0 °C and MgBrgoEtgo (0.17 mL, 1.0 M Et20/PhH (3:1), 0.17 mmol) was added. The Grignard solution of B was transferred via cannula to the precomplexed aldehyde solution. After stirring for 2 hours at 0 °C, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (0.2 mL) and water (0.1 mL). The phases were separated, and the organic phase was washed with water (0.2 mL) and brine (0.2 mL x 2). The combined aqueous phases were extracted with 820 (2x). The combined organics were dried over 166 MgSO4, filtered and concentrated to give 0.11 g of a yellow oil, which was purified by flash chromatography on silica gel [hexanes/EtOAc 25%] to give 63 mg (56 %) of a diastereomeric mixture of alcohol 100 as a yellow oil. Preparation of alkyne (101) via TMS deprotection: OPMB QWB / H WM / ; OPMB H 101 To a solution of TMS-alkyne 100 (0.033 g, 0.049 mmol) in THF (1 mL) was on added dropwise an acetic acid buffered TBAF solution (1.05:1) (0.060 mL, 0.060 mmol, 1.0M THF). After stirring for 4 hours at room temperature, 320 (4 mL) was added to the reaction and which was then quenched by the addition of a saturated aqueous NaHCOa solution (0.06 mL) and water (0.1 mL). The phases were separated. The organic phase was washed with brine (0.2 mL), dried over MgSO4, filtered and concentrated to give 29 mg (98 %) of alkyne 101 as a yellow oil, which was used crude in the subsequent reaction. Hydrostannylation of alkyne “101” to give vinyl stannane “102”: OPMB 99MB Wsns‘h OPMB SH 102 (PhaP)2PdCI2 (0.3 mg, 0.0005 mmol) and Red-Sil (0.089 9, 0.1872 mmol, 2.1 mmng) were added to 320 (0.5mL). A solution of crude alkyne 101 (0.028 g, 0.047 mmol) in 820 (0.5 mL), BuasnF (0.019 9, 0.0608 mmol) and a drop of TBAF (1.0 M THF) were added. After stirring for 2.5 hours at room temperature, the reaction was filtered through a pad of Celite on a glass frit . The Red-Sil filter cake was washed several times with ether. The filtrate was dried over MgSO4, filtered, and concentrated to give 31 mg of a yellow oil. The crude residue was 167 purified by flash chromatography on silica gel [hexanes/EtOAc 10% —> 25%] to give 17 mg (41%) of (E)-viny| stannane 102 as a diastereomeric regio-mixture. Preparation of diene (103) via Stille reaction: A solution of szdbaa (0.6 mg, 0.0006 mmol) and AsPha (0.8 mg, 0.0025 mmol) in NMP (0.1 mL) was stirred at room temperature for 10 minutes and followed by the addition of vinyl iodide 300“ (0.014 9, 0.0315 mmol) as an NMP solution (0.1 mL) to the yellowish-green solution. The reaction was immersed into a preheated oil bath (~45 °C) and a solution of vinyl stannane 102 (0.028 9, 0.0315 mmol) in NMP (0.2 mL) was added immediately. After stirring for 18 hours at 50 °C, the reaction was allowed to cool to room temperature and was then diluted with 320 (6 mL). The organic phase was washed with water (0.2 mL), brine (0.2 mL), a saturated aqueous KF solution (0.2 mL x 2) and brine (0.2 mL). The organics were dried over MgSO4, filtered and concentrated to give 0.11 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10% —> 25%] to give 7 mg (24%) of a diastereomeric mixture of diene 103 as a yellow oil. Preparation of TBS-ether (104): 168 PMB QPMB ms / : OPMB OTBS 104 To a solution of alcohol 100 (0.057 g, 0.085 mmol) in CH2CI2 (0.5 mL) were added 2,6-lutidine (0.020 mL, 0.17 mmol) and TBSOTf (0.030 mL, 0.13 mmol). After stirring for 10 minutes, the reaction was quenched with water (0.1 mL) and a saturated aqueous NH40I solution (0.1 mL). The reaction was diluted with Et20 (5 mL), and the phases were separated. The organic phase was washed with brine (0.2 mL x 2), dried over MgSO4, filtered and concentrated to give 91 mg of a yellow oil. The cnIde residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10% —-> 25%] to give 48 mg (72%) of a diastereomeric mixture of TBS-protected alcohol 104 as a clear oil. Preparation of 1-bromo-alkyne (105): TMS-alkyne 104 (0.048 g, 0.06 mmol) were dissolved in acetone (0.5 mL). NBS (0.013 g, 0.073 mmol) and AgNO;; (1 mg, 0.006 mmol) were added to the solution. After stirring for 65 minutes, the reaction mixture was diluted with water (0.25 mL) and 320 (2.5 mL). The phases were separated, and the organic phase was washed with brine (0.1 mL x 2), dried over MgSO4, filtered and concentrated to give 44 mg (90%) of a yellow oil, which was used crude in the subsequent reaction. 169 Preparation of vinyl stannane (106): OPMB QPMB WSW": OPMB Ores 106 (PhaP)2PdCl2 (0.4 mg, 0.0005 mmol) and Red-Sil (0.21 g, 0.43 mmol, 2.1 mmol/g) were added to 320 (0.6 mL). A solution of crude 1-bromo-alkyne 105 (0.043 g, 0.054 mmol) in EtZO (0.6 mL), BuasnF (0.037 g, 0.12 mmol) and a drop of TBAF (1.0 M THF) were added. After stirring for 1.5 hours at room temperature, the reaction was filtered through a pad of Celite on a glass frit. The residual Red-Sil was washed several times with 320. The filtrate was dried over MgSO4, filtered, and concentrated to give 69 mg of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 31 mg (57%) of diastereomeric mixture of vinyl stannane 106 as a yellow oil. Preparation of diene (107) via Liebeskind’s coupling: 107 To a solution of (2)-vinyl iodide 300“ (0.014 g, 0.031 mmol) in NMP (0.2 mL) was added copper (l) thiophene-2-carboxylate (CuTc) (0.009 g, 0.05 mmol). To this suspension was added a solution of vinyl stannane 106 in NMP (0.2 mL). After stirring for 50 minutes, the reaction was diluted with 320 (10 mL) and filtered through a bed of Celite. The green filter cake was washed with 320 (3 170 mL). The clear filtrate was washed with water (0.6 mL x 3), a saturated aqueous KF solution (0.5 mL x 2), and brine (0.6 mL). The organics were dried over MgSOa, filtered and concentrated to give 51 mg of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 16 mg (49%) of a diastereomeric mixture of diene 107 as a pink oil. Preparation of Piv-ester (108): OPMB gme PlvO i OTIPS 108 To a cold (0 °C) solution of alcohol 94 (0.092 g, 0.17 mmol) in CH20I2 (1.5 mL) were added pyridine (0.027 mL, 0.34 mmol) and a solution of PivCI (0.025 mL, 0.20 mmol) in CH20|2 (0.2 mL) dropwise. After stirring for 2.5 hours, the ice bath was removed and the reaction stirred at room temperature for 30 minutes. The reaction was quenched by the addition of water (0.1 mL) and then diluted with EtZO (4 mL). The phases were separated, and the organic phase was washed with a saturated aqueous CuSO4 solution (0.2 mL x 2), water (0.2 mL x 2) and brine. The organics were dried over MgSO4, filtered and concentrated to give 0.15 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 78 mg (74%) of fully protected tetra-oi 108 as a clear oil. Preparation of alcohol (109): OPMB QPMB Pivo ’ 109 171 To a solution of crude fully protected tetra-0| 108 (1.69 g, 2.31 mmol) in THF (15 mL) was added TBAF (2.8 mL, 1.0 M THF, 2.8 mmol) dropwise. After stirring for 5.5 hours the reaction was judged complete by TLC analysis. The reaction was then diluted with Etzo (40 mL) and water (2.5 mL) and the phases were separated. The organic phase was washed with brine (2.5 mL x 2). The combined aqueous phase was extracted with EtzO (2 mL). The combined organics were dried over MgSO4, filtered and concentrated to give 1.53 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25%] afforded 1.05 g (96% yield, 2 steps from 94) of alcohol 109 as a clear oil. via dial (1 18): To a cold (0 °C) solution of diol 118 (1.19 g, 3.06 mmol) in Cchlz (30 mL) were added pyridine (0.50 mL, 6.1 mmol) and a solution of PivCI (0.38 mL, 3.1 mmol) in CHZCIZ (2 mL) dropwise (~3 minutes). After stirring for 18 hours between 0 °C and room temperature, the reaction was quenched by the addition of water (1 mL) and a saturated aqueous NH4CI solution (1 mL). Et20 (35 mL) was added, and the phases were separated. The organic phase was washed with a saturated aqueous CuSO4 solution (7 mL x 2), water (5 mL x 2) and brine (5 mL), dried over MgSO4, filtered and concentrated to give 1.40 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 35% —> 75%] afforded 0.68 g (47%) of alcohol 109 as a clear oil and 0.33 g (28%) of recovered diol 118. For 109: IR (neat, 4 cm"): v = 3492, 2965, 2872, 2838, 1728, 1613, 1588, 1514, 1646, 1399, 1364, 1302, 1285, 1250, 1173, 1139, 1073, 1036, 927, 620; [6339 +91 .3° (c 1.095, CHCla); 1H NMR (300 MHz, CDCIa) 6 = 7.23 (d, J : 172 8.79 Hz, 4 H), 6.86 (d, J: 8.79 Hz, 2 H), 6.84 (d, J: 8.79 Hz, 2 H), 5.50 (s, 2 H), 4.55 (ABq, J: 11.54 Hz, 1 H), 4.54 (ABq, J: 11.54 Hz, 1 H), 4.33 (ABq, J: 11.54 Hz, 1 H), 4.25 (ABq, J : 11.54, 1 H), 4.14 - 4.07 (m, 2 H), 4.03 — 3.95 (m, 2 H), 3.79 (s, 3 H), 3.78 (s, 3 H), 3.56 (m, 2 H), 2.22 (dd, J: 8.79, 4.94 Hz, 1 H), 1.17 (s, 9 H); 13c NMR (75 MHz, 00013) 6 = 176.3, 159.3(2), 142.5, 129.9, 129.8, 129.5, 129.3, 117.2, 113.9, 113.8, 80.0, 70.5, 65.7, 65.3, 60.4, 55.2, 38.7, 27.2. Preparation of bisisopentylidene acetal (111): El El a+0 9X8 0% 111 To a 40 °C slurry of D-arabitol (15 g, 99 mmol) in DMF (15 mL) containing CSA (0.70 g, 3.0 mmol) was added 3,3-dimethoxypentane (29.0 g, 217 mmol) dropwise (~40 minutes). After stirring for an additional 5.5 hours, the reaction was quenched with Et3N (0.45 mL) and then concentrated via rotovap at 60 °C to afford a crude oil. The residue was diluted with 320 (200 mL) and then washed with brine (50 mL x 4), dried over MgSO4, filtered and concentrated to give 26 g (90%) of acetal 111 as a clear oil. Preparation of ketone (112): El El sf, 46 ’0 4 112 To a solution of alcohol 111 (1.0 g, 3.5 mmol) in Cchlz (35 mL) were added DMSO (2.46 mL, 34.7 mmol), I'-Pr2NEt (3.62 mL, 20.8 mmol) and 173 803-pyridine (1.65 g, 10.4 mmol). After stirring at room temperature for 90 minutes, the reaction was quenched with a saturated aqueous NH4CI solution (70 mL) and water (6 mL). Bio (140 mL) was added, and the phases were separated. The organic phase was washed with brine (20 x 2). The combined aqueous phase was extracted with 320 (20 mL x 3). The combined organics were dried over MgSO4, filtered and concentrated to give a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 0.68 g (68%) of ketone 112 as a clear oil. IR (neat, 4 cm"): v = 2975, 2944, 2664, 1736, 1464, 1360, 1262, 1201, 1173, 1062, 1061, 912,799; [(1339 +62.4° (c 0.66, CHCla); 1H NMR (300 MHz, CDCI3) 6 : 4.82 (t, J: 7.14 or 7.69 Hz, 2 H), 4.31 (t, J: 7.69 or 8.24 Hz, 2 H), 3.96 (dd, J: 7.14, 8.79 Hz, 2 H), 1.69 (m, 6 H), 0.93 (m, 12 H); “’0 NMR (75 MHz, cool.) 6 : 205.3, 114.9, 78.7, 66.2, 29.1, 26.2, 8.2, 8.0. Preparation of alkene (113): El El 233.5% 113 To a cold (0 °C) mixture of methyltriphenylphosphonium bromide (1.35 g, 3.77 mmol) in THF (5 mL) was added NaHMDS (3.5 mL, 1.0 M THF, 3.5 mmol) dropwise. The ice bath was removed and the reaction stirred at room temperature for 30 minutes before the temperature was lowered back to 0 °C. A solution of ketone 112 (0.20 g, 0.70 mmol) in THF (1 mL) was added dropwise and the reaction stirred for 3 hours at room temperature. The reaction was quenched by the addition of a saturated aqueous NH4CI solution (5 mL) and 174 water (5 mL). The reaction was diluted 320 (15 mL) and the phases were separated. The aqueous phase was extracted with Et20 (5 mL x 2). The combined organic phase was washed with brine (5 mL), dried over MgSO4, filtered and concentrated to give an oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5%] afforded 0.196 g (99%) of alkene 113 as a clear oil. IR (neat, 4 cm"): v : 2975, 2942, 2882, 1464, 1356, 1271, 1198, 1173, 1132, 1080, 1059, 1040. 920; [11339 +63.1° (c 0.90, CHCIa); 1H NMR (300 MHz, CDCI3) 6 : 5.29 (br s, 2 H), 4.50 (dd, J: 6.04, 8.79 Hz, 2 H), 4.18 (dd, J: 6.04, 7.69 Hz, 2 H), 3.55 (dd, J: 7.69, 8.79 Hz, 2 H), 1.64 (m, 4 H), 0.90 (t, J: 7.69 Hz, 3 H), 0.89 (t, J: 7.69 Hz, 3 H); ”0 NMR (75 MHz, CDCI3) 6 : 144.6, 112.8, 76.1, 70.0, 29.7, 29.4, 8.1 (2). Hydrolysis of acetal (113) to give tetra-oi (114): Ho QH Hovkrivow 114 To a solution of bisisopentylidene acetal 113 (5.08 g, 17.9 mmol) in MeOH/CH2Cl2 (2:1) (180 mL) was added CSA (0.83 g, 3.6 mmol) and water (3 mL). The reaction flask was immersed into a preheated oil bath (~40 °C). After stirring for 8.5 hours, the reaction was allowed to cool to room temperature and then concentrated under high vacuum overnight to give 3.73 g of crude tetra-0| 114 as a yellow oil. Preparation of TIPS-ether (115): 175 OH 9“ TIPso\/'\[(’\/orlps 115 To a solution of crude tetra-0| 114 (from above) in CH20l2/DMF (1 :1) (130 mL) were added imidazole (4.86 g, 71.4 mmol), DMAP (0.22 g, 1.8 mmol) and TIPSCI (8.0 mL, 37 mmol). After stirring for 12 hours, the reaction was concentrated to give a yellow residue. CH2CI2 (150 mL) was added to the residue and then washed with water (25 mL) and brine (25 mL x 2). The organics were dried over MgSO4, filtered and concentrated to give 9.54 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10% ~> 50%] afforded 6.3 g (77% yield, 2 steps) of TIPS disilylated tetra-0| 115 as a clear oil and 1.04 g (19% yield, 2 steps) of TIPS monosilylated tetra-0| 115a as a white solid. Preparation of fully protected tetra-oi (116): OPMB QPMe TIPSO ’ OTIPS 118 To a solution of tetra-oi 115 (2.30 g, 4.99 mmol) in cyclohexane/CH20I2 (3:1) (44 mL) were added PMB-imidate (5.64 g, 20 mmol) and CSA (0.12 g, 0.50 mmol). The reaction flask was immersed into a preheated oil bath (~40 °C). After stirring for 24 hours, additional CSA (60 mg) and PMB-imidate (2.8 g) were added. After stirring for a total of 50 hours, the reaction was allowed to cool to room temperature and was then quenched with a saturated aqueous NaHC03 solution (3 mL). Etzo (80 mL) was added and the phases were separated. The organic phase was washed with a saturated aqueous NaHCOa solution (3 mL x 176 2) and brine (4 mL). The organics were dried over MgSO4, filtered and concentrated to give a milky white solid. Hexanes were added to the residue. After stirring for several hours, the mixture was filtered and concentrated to give 5.3 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5%] afforded 1.35 g (38%) of fully protected tetra-oi 1 16 as a clear oil and 1.06 g (37%) of mono-protected PMB-ether derivative 117. Deprotection of TIPS-ether (1 16) to give diol (1 18): OPMB QPMB HO OH 118 To a solution of TIPS disilylated tetra-oi 116 (5.97 g, 8.51 mmol) in THF (90 mL) was added TBAF (19 mL, 1.0 M THF, 19 mmol) dropwise (~25 minutes). After stirring an additional 1.5 hours, the reaction was quenched by the addition of a saturated aqueous NH40I solution (10 mL) and water (10 mL). 151.0 (300 mL) was added and the phases were separated. The organic phase was washed with brine (10 mL x 2). The combined aqueous phases were extracted with EtZO (10 mL). The combined organics were dried over MgSO4, filtered and concentrated to give 7.6 g of a yellow oil, which was used crude in subsequent reactions. Preparation of aldehyde (110): opus QPMB PIvO i H 110 To a stirred solution of Dess-Martin periodinane (0.50 g, 1.2 mmol) in CHzclz (20 mL) were added pyridine (0.10 mL, 1.187 mmol) and a solution of 177 alcohol 109 (0.51 g, 1.1 mmol) in CHZCIz (2 mL). After stirring for 4 hours at room temperature, the reaction was quenched by the addition of a saturated aqueous NaHCOal10% aqueous Na28203 (1 :1) solution (20 mL) and diluted with Et20 (100 mL). After stirring for 30 minutes, the phases were separated. The organic phase was washed with water (4 mL), a saturated aqueous CuSO4 solution (4 mL x 2), water (4 mL x 2) and brine (8 mL), dried over Na2804, filtered and concentrated to give 0.50 g (100%) of crude aldehyde 110 as a yellow oil. IR (neat, 4 cm"): v : 2963, 2670, 2637, 1730, 1613, 1514, 1464, 1397, 1366, 1263, 1250, 1173, 1157, 1078, 1034, 822; [113394.500 (c 0.665, CHCI3); 1H NMR (300 MHz, CDCI3) 6 : 9.51 (d, J: 1.65 Hz, 1 H), 7.23 (d, J: 8.79 Hz, 1 H), 7.19 (d, J: 8.79 Hz, 2 H), 6.85 (d, J: 8.79 Hz, 2 H), 6.83 (d, J: 8.79 Hz, 2 H), 5.51 (s, 1 H), 5.48 (s, 1 H), 4.57 (ABq, J: 11.54 Hz, 1 H), 4.44 (s, 1 H), 4.38 (ABq, J: 11.54 Hz, 1 H), 4.13 - 4.22 (m, 3 H), 4.06 -4.12 (m, 2 H), 3.77 (s, 3 H), 3.76 (s, 3 H), 1.15 (s, 9 H); "’0 NMR (75 MHz, CDCI3) 6 :199.1, 176.1, 159.5, 159.2, 140.3, 129.6, 129.5, 128.7, 1205,1139, 113.7, 64.0, 77.9, 70.9, 70.5, 65.6, 55.2, 36.6, 27.1. Preparation of alcohol (119) ~ Fragment AB coupling: OPMB 9PMB TMS WOW 81+ 119 t-BuLi (2.85 mL, 1.7 M pentane, 4.85 mmol) was added dropwise to 320 (12 mL) at ~78 °C. A solution of vinyl bromide B (0.52 g, 2.4 mmol) in 320 (5 mL) was added dropwise to the t-BuLi solution. After stirring for 10 minutes, MgBrZ-Etzo (2.60 mL, 1.0 M Et20/PhH (3:1), 2.60 mmol) was added and the 178 reaction stirred at ~78 °C for 15 minutes and then at 0 °C for 10 minutes. In a separate flask, to a 0 °C solution of crude aldehyde 110 (0.76 g, 1.62 mmol) in CHZCIZ (8 mL) was added MgBrzoEtzo (1.60 mL, 1.0 M 320th (3:1) 1.60 mmol) and the solution stirred for several minutes. The Grignard solution was transferred via cannula to the precomplexed aldehyde solution. After stirring for 45 minutes at 0 °C, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (1.5 mL) and water (1.5 mL). The reaction was diluted with Et20 and the phases were separated. The organic phase was washed with water (0.7 mL) and brine (0.7 mL x 2). The combined aqueous phases were extracted with 320 (2x). The combined organics were dried over MgSO4, filtered and concentrated to give 1.11 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25%] afforded 0.57 g (58%) of alcohol 119 as a yellow oil. IR (neat, 4 cm"): v = 3382, 2961, 2917, 2885, 2178, 1727, 1653, 1617, 1514, 1456, 1250, 1154, 1036, 843,760; [oEQ,+72.3° (c 0.495, CHCla); 1H NMR (500 MHz, CDCIa) 6 = 7.22 (d, J: 6.39 Hz, 2 H), 7.19 (d, J: 8.39 Hz, 2 H), 6.85 (d, J: 8.39 Hz, 2 H), 6.84 (d, J: 8.39 Hz, 2 H), 5.57 (s, 1 H), 5.48 (s, 1 H), 5.36 (s, 1 H), 5.19 (s, 3 H), 4.53 (ABq, J: 10.99 Hz, 1 H), 4.51 (ABq, J: 11.54 Hz, 1 H), 4.36 (ABq, J: 11.54 Hz, 1 H), 4.29 (d, J: 9.34 Hz, 1 H), 4.24 (ABq, J: 10.99 Hz, 1 H), 3.97 - 4.14 (series m, 2 H), 3.90 (d, J: 4.94 Hz, 1 H), 3.78 (m, 1 H), 3.78 (s, 1 H), 3.77 (s, 3 H), 3.06 (ABq, J: 19.78 Hz, 1 H), 2.92 (ABq, J: 19.78 Hz, 1 H), 2.65 (d, J: 4.40 Hz, 1 H), 1.16 (s, 9 H), 0.12 (s, 9 H); “’0 NMR (125 MHz, 00013) 6 : 176.3, 159.5, 159.4, 143.1, 142.7, 130.3, 129.7, 129.5, 129.2, 116.8, 114.7, 114.0, 113.9, 103.6, 87.8, 80.4, 77.6, 179 76.0, 71 .2, 70.9, 66.1, 55.3, 38.8, 27.2, 23.4, 0.07; HRMS (Cl) m/z 626.3513 [(M + NH..)*; calcd for 035H52078iN, 626.3501]. Preparation of TBS-ether (1 20): OPMB gpMe TMs PIVOW 6768 120 To a cold (0 °C) solution of alcohol 119 (1 .11 g, 1.82 mmol) in CHZCIZ (18 mL) was added 2,6-lutidine (0.27 mL, 2.3 mmol) and TBSOTf (0.48 mL, 2.1 mmol). After stirring for 30 minutes at 0 °C, the reaction was quenched with water (1.4 mL) and a saturated aqueous NH4CI solution (1.4 mL). The reaction was diluted with Etzo (90 mL) and the phases were separated. The organic phase was washed with a saturated aqueous CuSO.( solution (1 mL x 2), water (1 mL x 2) and brine (2 mL), dried over M9304, filtered and concentrated to give 1.36 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 1.07 g (81 %) of TBS-silylated alcohol 120 as a clear oil. IR (neat, 4 cm"): v = 2955, 2858, 2174, 1720, 1613, 1587, 1514, 1464, 1362, 1302, 1157, 1099, 862, 641; [6339 +19.6° (c 0.57, CHCI3); 1H NMR (300 MHz, CDCIa) 6 : 7.29 (d, J: 8.79 Hz, 4 H), 6.89 (d, J: 8.24 Hz, 4 H), 5.57 (s, 1 H), 5.41 (s, 1 H), 5.33 (d, J: 1.65 Hz, 1 H), 5.16 (s, 1 H), 4.56 (ABq, J : 11.54 Hz, 1 H), 4.55 (ABq, J: 10.99 Hz, 1 H), 4.46 (d, J: 4.94 Hz, 1 H), 4.35 (ABq, J: 10.99 Hz, 1 H), 4.33 (ABq, J: 10.99 Hz, 1 H), 4.23 - 4.27 (m, 2 H), 3.90 - 4.0 (m, 2 H), 3.83 (s, 3 H), 3.82 (s, 3 H), 3.20 (ABq, J: 19.78 Hz, 1 H), 3.10 (ABq, J: 19.78 2, 1 H), 1.24 (s, 9 H), 0.87 (s, 9 H), 0.19 (s, 9 H), 0.03 (s, 6 H); ‘30 NMR (75 MHz, 00013) 6 : 178.4, 159.0, 142.9, 142.6, 130.7, 130.4, 180 129.0 (2), 114.3, 113.7, 104.3, 86.9, 81.0, 78.1 , 77.3, 71 .2, 70.9, 66.1 , 55.2, 38.7, 27.2, 25.6, 24.4, 18.1 , 0.1, -5.1; HRMS (FAB) m/z 723.4119 [(M + NH4)+;,calcd for C41 H6607SlzN, 723.41 12]. Preparation of alcohol (121): OPMB 9m TMS HOW 816s 121 To a cold (0 °C) solution of Piv-ester 120 (1.07 g, 1.48 mmol) in THF (12 mL) was added dropwise (~3 minutes) Super-Hydride‘D (3.11 mL, 1.0 M THF, 3.11 mmol). After stirring for 35 minutes, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (3.1 mL), glycerol (0.93 mL, 0.3 mL/mmol) and water (3.1 mL) and then the reaction mixture was diluted with Et20 (100 mL). After stirring for 60 minutes, the phases were separated. The organic phase was washed with brine (1.5 mL), 0.5 M NaOH (1.5 mL x 2), and brine (1.5 mL). The combined aqueous phases were extracted with Et20 (3 mL). The combined organics were dried over MgSOa, filtered and concentrated to give 1.33 g of a clear oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 25%] to give 0.83 g (88 %) of alcohol 121 as a clear oil. IR (neat, 4 cm"): v :3455, 2957, 2932, 2697, 2659, 2176, 1613, 1514, 1464, 1302, 1250, 1173, 1096, 1063, 1038, 641, 777, 760; [ng9 +26.3° (c 0.51, CHCI3); 1H NMR (300 MHz, CDCla) 6 : 7.23 (d, J: 8.79 Hz, 2 H), 7.22 (d, J: 8.79 Hz, 2 H), 6.86 (d, J: 8.79 Hz, 2 H), 6.84 (d, J = 8.79 Hz, 2 H), 5.47 (s, 1 H), 5.35 (s, 1 H), 5.29 (s, 1 H), 5.11 (s, 1 H), 4.55 (ABq, J: 10.99 Hz, 1 H), 4.50 (ABq, J= 12.09 Hz, 1 H), 4.40 (d, J: 5.49 Hz, 1 H), 4.28 (ABq, J= 11.54 Hz, 1 181 H), 4.23 (ABq, J= 10.99 Hz, 1 H), 4.08 (m, 1 H), 3.78 (s, 6 H), 3.78 (m, 1 H), 3.63 (m, 1 H), 3.39 (ddd, J: 4.40, 7.14, 11.54 Hz, 1 H), 3.16 (ABq, J: 19.29 Hz, 1 H), 3.04 (ABq, J: 19.78 Hz, 1 H), 2.14 (dd, J: 9.34, 3.85 Hz, 1 H), 0.84 (s, 9 H), 0.14 (s, 9 H), -0.01 (s, 6 H); “‘0 NMR (75 MHz, 00013) 6 : 159.2, 159.1, 142.9, 142.6, 130.5, 130.3, 129.3, 129.0, 114.5, 113.8, 113.7, 104.2, 80.7, 80.6, 70.9, 70.7, 64.6, 55.2, 25.8, 24.4, 16.2, 0.08, -5.1; HRMS (c1) m/z 639.3510 [(M + H)‘; calcd for CaeHssoesiz, 639.3537]. Preparation of aldehyde (122): owe gpMe ms ”W o 5166 122 To a stirred solution of Dess-Martin periodinane (0.64 g, 1.5 mmol) in CHQCIZ (25 mL) were added pyridine (0.13 mL, 1.5 mmol) and a solution of alcohol 121 (0.80 g, 1.3 mmol) in CHzclz (5 mL). After stirring for 1.5 hours at room temperature, the reaction was quenched by the addition of a saturated aqueous NaHCO:J10°/o aqueous Na2$203 (1 :1) solution (22 mL) and then diluted with Eth (170 mL). After stirring for 60 minutes, the phases were separated. The organic phase was washed with water (4 mL), a saturated aqueous CuSO4 solution (4 mL x 2), water (4 mL x 2) and brine (8 mL), dried over N62804, filtered and concentrated to give 0.74 g (93%) of crude aldehyde 122 as a yellow oil. IR (CHCI3, 4 cm"): v : 2955, 2857, 2174, 1730, 1613, 1566, 1514, 1464, 1362, 1304, 1101, 1003, 910, 662, 841; [11339 -55.2° (c 0.545, CHCla); 1H NMR (300 MHz, cock.) 6 : 9.33 (d, J: 2.75 Hz, 1 H), 7.24 (d, J: 8.79 Hz, 2 H), 7.20 (d, J : 8.79 Hz, 2 H), 6.66 (d, J: 8.79 Hz, 2 H), 6.83 (d, J: 8.79 Hz, 2 H), 5.52 (s, 1 182 H), 5.41 (s, 1 H), 5.26 (s, 1 H), 5.05 (s, 1 H), 4.52 (ABq, J: 11.54 Hz, 1 H), 4.42 (ABq, J : 11.54 Hz, 1 H), 4.42 - 4.32 (m, 3 H), 4.18 (ABq, J: 10.99 Hz, 1 H), 3.91 (d, J: 5.49 Hz, 1 H), 3.79 (s, 3 H), 3.78 (s, 3 H), 3.11 (ABq, J: 19.78 Hz, 1 H), 2.98 (ABq, J: 19.78 Hz, 1 H), 0.63 (s, 9 H), 0.14 (s, 9 H), -0.02 (s, 3 H), - 0.03 (s, 3 H); 13c NMR (75 MHz, cock.) 6 : 199.1, 159.4, 159.0, 142.9, 139.7, 130.3, 129.5, 129.4, 129.2, 117.0, 114.4, 113.9, 113.5, 104.3, 87.0, 84.3, 61.2, 71.6, 70.9, 55.2, 25.8, 24.0, 16.2, 0.08, -5.1, -5.2. Preparation of alcohol (123): OPMB 99MB TMS W / ; OH 6166 123 To a cold (0 °C) solution of crude aldehyde 122 (0.74 g, 1.2 mmol) in a EtZO/PhH/CHZClz (3:1:1) solution (18 mL) was added MgBrzoEtZO (1.3 mL, 1.0 M EtZO/PhH (3:1), 1.3 mmol). After stirring for 6 minutes, vinyl magnesium bromide (2.3 mL, 1.0 M THF, 2.3 mmol) was added dropwise (~ 12 minutes). After stirring for 60 minutes at 0 °C, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (1 mL) and water (1 mL). The reaction mixture was diluted with 320 (40 mL) and the phases separated. The organic phase was washed with water (2 mL) and brine (2 mL). The combined aqueous phases were extracted with Et20. The combined organics were dried over MgSO4, filtered and concentrated to give 0.74 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 0.45 g (58%) of alcohol 123 as a clear oil. IR (neat, 4 cm"): v = 3552, 2958, 2932, 2900, 2858, 2176, 1614, 1514, 1464, 1362, 1303, 1250, 1173, 1091, 1037, 921, 183 841, 779, 760; [dfigg +6.6° (c 0.575, CHCI3); 1H NMR (500 MHz, CDCI3) 6 : 7.26 (d, J: 8.39 Hz, 2 H), 7.22 (d, J: 8.39 Hz, 2 H), 6.86 (d, J: 8.39 Hz, 4 H), 5.90 (ddd, J: 17.23, 10.16, 5.30 Hz, 1 H), 5.50 (s, 1 H), 5.42 (s, 1 H), 5.33 (s, 1 H), 5.31 (m, 1 H), 5.18 (s, 1 H), 5.15 (m , 1 H), 4.55 (ABq, J: 11.49 Hz, 1 H), 4.54 (ABq, J: 11.05 Hz, 1 H), 4.50 (d, J: 4.66 Hz, 1 H), 4.35 (ABq, J: 11.49 Hz, 1 H), 4.23 (ABq, J: 10.60 Hz, 1 H), 4.03 (br s, 2 H), 3.93 (d, J: 4.86 Hz, 1 H), 3.79 (s, 6 H), 3.17 (ABq, J: 19.44 Hz, 1 H), 3.10 (ABq, J: 19.66 Hz, 1 H), 0.66 (s, 9 H), 0.16 (s, 9 H), 0.01 (s, 3 H), 0.01 (s, 3 H); “’0 NMR (125 MHz, CDCI3) 6 : 159.2, 159.1, 143.1, 142.9, 138.2, 130.6, 130.5, 129.3, 129.1, 128.9, 116.1, 114.4, 113.8, 113.7, 104.5, 86.8, 62.1, 60.5, 73.5, 71.7, 70.8, 55.2, 25.9, 24.6, 16.3, 14.1, 0.10, -5.0, -5.1; HRMS (Cl) m/z 665.3695 [(M + H)‘; calcd for C38H5706$i2, 665.3694]. Preparation of 1-bromo-alkyne (124): oPMe QPMB 6r 5 // W OH OTBS 124 TMS-alkyne 123 (0.31 g, 0.47 mmol) was dissolved in acetone (5 mL) and NBS (0.10 g, 0.56 mmol) and AgNOa (0.020 g, 0.12 mmol) were added. After stirring for 3 hours the reaction was judged complete by TLC analysis. The reaction was quenched by the addition of water (1 mL) and then diluted with EtzO (35 mL). The phases were separated, and the organic phase was washed with brine (1 mL x 2), dried over MgSOa, filtered and concentrated to give 0.43 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/ EtOAc 10%] afforded 0.28 g (92%) of 1-bromo-alkyne 124 as a clear oil. 1H NMR (500 184 MHz, CDCI3) 6 : 7.24 (d, J: 8.84 Hz, 2 H), 7.22 (d, J: 8.39 Hz, 2 H), 6.86 (d, J : 8.84 Hz, 4 H), 5.69 (ddd, J: 16.79, 10.16, 5.30 Hz, 1 H), 5.50 (s, 1 H), 5.41 (s, 1 H), 5.32 (s, 1 H), 5.29 (s, 1 H), 5.18 (s, 1 H), 5.16 (s, 1 H), 4.55 (ABq, J: 11.93 Hz, 1 H), 4.53 (ABq, J: 10.60 Hz, 1 H), 4.41 (d, J: 4.86 Hz, 1 H), 4.31 (ABq, J: 11.93 Hz, 1 H), 4.23 (ABq, J: 11.05 Hz, 1 H), 4.02 (m, 2 H), 3.92 (d, J: 4.86 Hz, 1 H), 3.79 (s, 6 H), 3.17 (ABq, J: 19.44 Hz, 1 H), 3.04 (ABq, J: 19.44 Hz, 1 H), 2.45 (br s, -OH), 0.85 (s, 9 H), -0.01 (s, 6 H); "*0 NMR (125 MHz, CDCIa) 6 : 159.2, 159.1, 142.9, 142.6, 136.1, 1305,1304, 1293,1290, 116.2, 114.5, 114.4, 113.7, 62.0, 80.5, 77.7, 77.5, 73.5, 71.7, 70.6, 552,402,295, 25.9, 24.3, 18.3, -5.1 (2); HRMS (FAB, NBA + KI) m/z 709.1994 [(M + K)‘; calcd for C35H4yosBrSiK, 709.1962]. Preparation of vinyl stannane (125): OPMB QPMB ’ \ SnB OH 6766 125 To a solution of (PhaP)2PdCl2 (2 mg, 0.003 mmol), Red-Sil (0.94 g, 2.0 mmol, 2.1 mmol/9), and BuasnF (0.17 g, 0.55 mmol) in EtZO (4.5 mL) was added of a solution of 1-bromo-alkyne 124 (0.167 g, 0.248 mmol) in 320 (0.5 mL) and a drop of TBAF (1.0 M THF). After stirring for 2.5 hours at room temperature, the reaction was filtered through a pad of Celite on a glass frit. The residual Red-Sil was washed several times with Et20. The filtrate was dried over MgSO... filtered, and concentrated to give 0.27 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10% —+ 15%] to give 0.16 g (73%) of E-vinyl stannane 125 as a clear oil. IR (neat, 4 cm"): v = 2955, 2928, 185 2855,1613,1514,1464,1361,1302,1250,1173,1084,1040,920,835,777; [61339 +3.6° (c 0.555, CHCI3); 1H NMR (500 MHz, cool.) 6 : 7.25 (d, J: 8.84 Hz, 2 H), 7.21 (d, J: 8.84 Hz, 2 H), 6.85 (d, J: 8.84 Hz, 2 H), 6.84 (d, J: 8.84 Hz, 2 H), 5.95 — 5.65 (m, 3 H), 5.50 (s, 1 H), 5.45 (s, 1 H), 5.30 (m, 1 H), 5.16 (m, 1 H), 5.07 (s, 1 H), 4.94 (s, 1 H), 4.56 (ABq, J: 11.49 Hz, 1 H), 4.54 (ABq, J: 11.05 Hz, 1 H), 4.34 (m, 2 H), 4.20 (ABq, J: 11.05 Hz, 1 H), 4.03 (m, 2 H), 3.92 (d, J: 5.30 Hz, 1 H), 3.79 (s, 6 H), 3.0 (m, 2 H), 2.39 (d, J: 5.74 Hz, 1 H), 1.50 (m, 6 H), 1.30 (m, 6 H), 0.87 (m, 24 H), 001 (6,3 H), -0.02 (s, 3 H); “’0 NMR (125 MHz, CDCI3) 6 :1592, 159.1, 146.6, 143.2, 136.3, 130.7, 130.6, 130.2, 129.3, 129.0, 116.0, 114.2, 113.7, 113.7, 113.1, 81.9, 80.8, 78.0, 73.4, 71.7, 70.7, 55.3, 55.2, 41.5, 29.1, 27.3, 25.9, 18.3, 13.7, 9.4, 4.9, -5.0; HRMS (El) m/z 623.3694 [(M - Bu)*; calcd for CuHayossiSn, 823.3726]. Preparation of diene (126) via Liebeskind’s coupling: To a cold (0 °C) solution of (2)-vinyl iodide 3005" (0.12 g, 0.27 mmol) in NMP (1 mL) was added copper (I) thiophene-2-carboxylate (CuTc) (0.039 g, 0.204 mmol). To this suspension was added a solution of vinyl stannane 125 (0.12 g, 0.14 mmol) in NMP (0.5 mL). After stirring 15 minutes at 0 °C, the ice bath was removed and the reaction stirred at room temperature for 15 minutes. The reaction mixture was diluted with 320 (20 mL) and filtered through a pad of 186 Celite on a glass frit. The green filter cake was washed with EtzO (3x). The yellow filtrate was washed with water (2 mL x 3), a saturated aqueous KF solution (2 mL x 2), and brine (2 mL). The organics were dried over MgSO4, filtered and concentrated to give 0.23 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10% —-) 15%] to give 75 mg (60%) of diene 126 as a clear oil. IR (neat, 4 cm"): v : 3513, 3077, 2959,2930,1715,1636,1613,1588,1514,1464,1381,1302,1248,1173,1150, 1074, 1036, 914, 635, 779; [61239 -6° (c 0.205, CHCI3); 1H NMR (500 MHz, cool.) 8 : 7.64 (d, J: 15.91 Hz, 1 H), 7.25 (d, J: 8.39 Hz, 2 H), 7.21 (d, J: 8.39 Hz, 2 H), 6.85 (m, 4 H), 6.11 (dt, J: 15.91, 7.51 Hz, 1 H), 5.90 (m, 1 H), 5.76 (s, 1 H), 5.68 (s, 1 H), 5.51 (s, 1 H), 5.45 (s, 1 H), 5.31 (d, J: 17.23 Hz, 1 H), 5.16 (d, J: 10.60 Hz, 1 H), 5.09 (s, 1 H), 5.03 (d, J: 7.51 Hz, 1 H), 5.01 (s, 1 H), 4.93 (m, 1 H), 4.63 (s, 1 H), 4.76 (s, 1 H), 4.65 (t, J: 6.19 Hz, 1 H), 4.57 (ABq, J: 11.93 Hz, 1 H), 4.54 (ABq, J:11.05 Hz, 1 H), 4.34 (m, 1 H), 4.32 (ABq, J: 11.49 Hz, 1 H), 4.22 (ABq, J : 11.05 Hz, 1 H), 4.04 (br 6,2 H), 3.94 (d, J: 4.86 Hz, 1 H), 3.78 (s, 6 H), 3.09 (dABq, J: 6.63, 16.35 Hz, 1 H), 3.00 (dABq, J: 7.95, 15.91 Hz, 1 H), 2.87 (dd, J=2.21, 6.19 Hz, 1 H), 2.71 (t, J: 7.51 Hz, 2 H), 2.62 (dd, J : 2.21, 7.07 Hz, 1 H), 2.44 (d, J: 5.30 Hz, 1 H), 2.30 (dABq. J: 4.42, 13.70 Hz, 1 H), 2.05 (m, 1 H), 1.98 (s, 3 H), 1.83 (m, 1 H), 1.50- 1.20 (series m, 5 H), 0.95 (d, J: 6.63 Hz, 3 H), 0.91 (d, J: 7.07 Hz, 3 H), 0.85 (m, 3 H), 0.84 (s, 9 H), -0.03 (s, 3 H), -0.04 (s, 3 H). Ring-closing metathesis of diene (126) to give (2)-macrocycle (127): 187 127 To a slightly refluxing solution of diene 126 (74 mg, 0.081 mmol) in CH2012 (74 mL) was added dropwise (~8 hours) a solution of bis(tricyclohexylphosphine) benzylidene ruthenium dichloride (33 mg, 0.040 mmol) in CH20I2 (8 mL). After stirring an additional 18 hours at reflux, the reaction was allowed to cool to room temperature and then concentrated to give 0.14 g of a black residue. The black residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 34 mg (47%) of (2)-macrocycle 127 and 10 mg (14%) of ketone 128 as oils. For spectroscopic data see below. 2"” generation catalyst: To a slightly refluxing solution of diene 126 (26 mg, 0.029 mmol) in CH20I2 (26 mL) was added dropwise (~2 hours) a solution of PhHC=Ru(PCy3)(IMes- H2)CI2 (5 mg, 0.006 mmol) in CH20I2 (2 mL). After stirring an additional 8 hours at reflux, the reaction was allowed to cool to room temperature and then concentrated to give 33 mg of a black residue. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 22 mg (88%) of macrocycle 127. macrocycle 127: IR (neat, 4 cm"): v = 3515, 2957, 2930, 2857, 1709, 1636, 1613, 1514, 1464, 1381, 1302, 1248, 1173, 1154, 1074, 1038, 909, 835, 777; [c.1339 +37.5° (c 0.557, CHCI3); 1H NMR (500 MHz, CDCla) 6 : 7.41 (d, J: 15.91 188 Hz, 1 H), 7.23 (d, J: 8.84 Hz, 2 H), 7.19 (d, J: 8.84 Hz, 2 H), 6.84 (d, J: 8.84 Hz, 2H), 6.82 (d, J: 8.84 Hz, 2 H), 6.19 (dt, J = 15.91, 7.51 Hz, 1 H), 5.65 (s, 1 H), 5.61 (m, 2 H), 5.54 (dd, J: 4.86, 15.46 Hz, 1 H), 5.50 (s, 1 H), 5.13 (s, 1 H), 4.95 (s, 1 H), 4.86 (s, 1 H), 4.74 (s, 1 H), 4.64 (dd, J: 3.53, 6.63 Hz, 1 H), 4.52 (ABq, J = 11.49 Hz, 1 H), 4.48 (ABq, J:10.60 Hz, 1 H), 4.26 (ABq, J: 11.05 Hz, 1 H), 4.20 (ABq, J: 11.49 Hz, 1 H), 4.19 (d, J: 6.19 Hz, 1 H), 3.96 (br s, 1 H), 3.79 (s, 3 H), 3.78 (s, 3 H), 3.78 (m, 1 H), 3.69 (br s, 1 H), 3.07 (dABq, J: 7.51, 15.91 Hz, 1 H), 2.96 (dABq, J: 6.19, 15.46 Hz, 1 H), 2.90 (dd, J: 2.21, 6.63 Hz, 1 H), 2.78 (dABq, J: 6.19, 14.58 Hz, 1 H), 2.64 (dABq. J = 5.74, 14.58 Hz, 1 H), 2.59 (dd, J: 2.21, 7.51 Hz, 1 H), 2.30 ~ 2.20 (m, 3 H), 1.86 (d, J: 1.33 Hz, 3 H), 1.78 (m, 1 H), 1.50 — 1.20 (series m, 5 H), 0.98 (d, J: 7.07 Hz, 3 H), 0.92 (d, J: 6.63 Hz, 3 H), 0.88 (m, 12 H), 0.02 (s, 3 H), 0.01 (s, 3 H). ketone 128: IR (neat, 4 cm"): v : 2957, 2930, 2857, 1715, 1636, 1613, 1514, 1464, 1389, 1358, 1302, 1250, 1173, 1150, 1074, 1038, 912, 835,777; 1H NMR (500 MHz, CDCIa) 8 = 7.59 (d, J: 15.46 Hz, 1 H), 7.22 (d, J: 8.39 Hz, 2 H), 7.19 (d, J = 8.84 Hz, 2 H), 6.85 (d, J: 8.39 Hz, 2H), 6.83 (d, J = 8.84 Hz, 2 H), 6.06 (dt, J =15.91,7.51 Hz, 1 H), 5.75 (m, 1 H), 5.66 (s, 1 H), 5.60 (s, 1 H), 5.39 (s, 1 H), 5.00 (series m, 3 H), 4.82 (s, 2 H), 4.75 (s, 1 H), 4.64 (dd, J: 4.86, 6.19 Hz, 1 H), 4.44 (ABq, J: 11.49 Hz, 1 H), 4.35 (ABq, J: 11.49 Hz, 1 H), 4.33 (s, 1 H), 4.32 (ABq, J: 11.05 Hz, 1 H), 4.23 (d, J: 5.74 Hz, 1 H), 4.14 (ABq, J: 11.49 Hz, 1 H), 3.93 (d, J = 5.74 Hz, 1 H), 3.78 (s, 3 H), 3.77 (s, 3 H), 3.02 (dABq, J: 6.63, 16.35 Hz, 1 H), 2.90 (dABq, J: 6.63, 16.35 Hz, 1 H), 2.86 (dd, J: 2.21, 6.19 Hz, 1 H), 2.70 (t, J: 7.51 Hz, 2 H), 2.60 (dd, J: 2.21, 7.07 Hz, 1 H), 2.29 189 (dABq, J: 4.86, 13.70 Hz, 1 H), 2.11 (s, 3 H), 2.03 (m, 1 H), 1.97 (s, 3 H), 1.61 (dABq, J : 9.72, 13.70 Hz, 1 H), 1.50 — 1.20 (series m, 5 H), 0.95 (d, J: 7.07 Hz, 3 H), 0.90 (d, J: 7.07 Hz, 3 H), 0.87 (t, J: 7.07 Hz, 3 H), 0.62 (s, 9 H), -0.04 (s, 3 H), -0.06 (s, 3H). DDQ deprotection of PMB-ether (123) to give alcohol (130): O A 0 9H TMS : // PMP / . mmmfasm... To a solution of PMB-ether123 (24 mg, 0.036 mmol) in t-BuOH/aqueous pH=7 buffer/CH20I2 (1 :1 :5) (1.4 mL) was added 2,3-dichloro-5,6-dicyano-1,4- benzoquinone (DDQ) (33 mg, 0.14 mmol). After stirring for 2 hours, the red reaction mixture was diluted with CHzclz (10 mL) and a saturated aqueous NaHCOa solution (10 mL) and then separated the phases. The aqueous phase was extracted with CH20I2 (5 mL x 3). The combined organic phases were washed with a saturated aqueous NaHCOa solution (10 mL), water (10 mL) and brine (10 mL), dried over MgSO4, filtered, and concentrated to give 24 mg of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 11 mg (56%) of PMB-ester 130 as a clear oil, which is a mixture of regioisomers. Preparation of TBS-ether (131): OPMB 99MB / TMS TBS 6766 131 190 To a cold (0 °C) solution of alcohol 123 (0.26 g, 0.39 mmol) in CH2012 (4 mL) were added 2,6-lutidine (0.060 mL, 0.51 mmol) and TBSOTf (0.11 mL, 0.47 mmol). After stirring for 20 minutes, the reaction was quenched with water (0.20 mL) and a saturated aqueous NHzcl solution (0.20 mL). The reaction was diluted with EtQO (20 mL) and the phases were separated. The organic phase was washed with brine (0.5 mL x 2), dried over MgSO4, filtered and concentrated to give 0.35 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 5% -->10%] to give 0.25 g (82 %) of fully protected tetra-0| 131 as a clear oil. IR (CHCIa, 4 cm"): v : 2930, 2857, 2174,1711,1613,1588,1514,1464,1362,1302,1099,1005,912,864,841; [41%;], -22.5° (c 0.525, CHCI3); ‘H NMR (500 MHz, cool.) 6 : 7.24 (app t, J: 7.95 or 8.84 Hz, 4 H), 6.85 (app t, J: 7.51 or 8.39 Hz, 4 H), 5.91 (ddd, J: 4.86, 10.60, 17.23 Hz, 1 H), 5.40 (s, 1 H), 5.37 (s, 1 H), 5.33 (d, J: 1.33 Hz, 1 H), 5.20 (m, 1 H), 5.14 (s, 1 H), 5.10 (m, 1 H), 4.57 (ABq, J: 11.05 Hz, 1 H), 4.53 (ABq, J : 11.05 Hz, 1 H), 4.32 (m, 4 H), 4.20 (d, J: 5.74 Hz, 1 H), 3.94 (d, J: 4.86 Hz, 1 H), 3.79 (s, 6 H), 3.21 (ABq, J: 20.32 Hz, 1 H), 3.10 (ABq, J: 20.32 Hz, 1 H), 0.92 (s, 9 H), 0.88 (s, 9 H), 0.14 (s, 9 H), 0.08 (s, 3 H), 0.02 (6,3 H), 0.017 (s, 3 H), 0.002 (s, 3 H); 13c NMR (125 MHz, c0013) 6 : 158.9, 156.6, 144.2, 143.3, 137.4, 131.6, 131.4, 128.8, 128.7, 115.5, 114.5, 113.7, 113.6, 113.5, 104.5, 87.3, 82.2 (2), 78.8, 76.5, 71.2, 70.9, 55.2, 31.6, 26.0, 25.9, 24.5, 22.6, 18.3, 18.2, 14.1, 0.12, -4.7, -4.8, -4.9, -4.9. DDQ deprotection of PMB-ether (131) to give dial (132): 191 OHQl-I ms 2 / . / / OTBS OTBS 1 32 To a solution of PMB-ether 131 (0.22 g, 0.28 mmol) in t-BuOH/ aqueous pH=7 buffer/CHZClz (1 :1 :5) (14 mL) was added 2,3-dichloro-5,6-dicyano-1,4- benzoquinone (DDQ) (0.19 g, 0.85 mmol). After stirring for 60 minutes, additional DDQ (65 mg) was added. After stirring an additional 5.5 hours, the red reaction mixture was diluted with CH2CI2 (30 mL) and a saturated aqueous NaHCOs solution (10 mL) and then the phases were separated. The aqueous phase was extracted with CH2Cl2 (5 mL x 3). The combined organic phase was washed with a saturated aqueous NaHCOa solution (10 mL), water (10 mL) and brine (10 mL), dried over MgSO4, filtered, and concentrated to give 0.21 g of a red oil. The crude residue was purified by flash chromatography on silica gel [hexanes/ EtOAc 5%] to give 90 mg (59%) of diol 132 as a light yellow oil. IR (neat, 4 cm"): v : 3560, 2957, 2930,2899, 2859, 2178, 1701, 1603, 1560, 1512, 1471, 1464, 1406, 1362, 1252, 1161, 1074, 1032, 930, 639, 779; [11339 -23.4° (c 0.435, CHCI3); ‘H NMR (500 MHz, 00013) 6 : 5.83 (ddd, J: 6.63, 10.60, 17.23 Hz, 1 H), 5.34 ~ 5.14 (series m, 6 H), 4.31 (d, J: 4.42 Hz, 1 H), 4.10 (t, J: 6.19 Hz, 1 H), 3.89 (t, J : 5.30 or 4.86 Hz, 1 H), 3.80 (t, J: 5.30 or 4.86 Hz, 1 H), 3.10 (ABq, J: 19.88 Hz, 1 H), 3.01 (ABq, J: 19.88 Hz, 1 H), 2.67 (d, J: 5.74 Hz, -OH), 2.86 (d, J: 3.98 Hz, -OH), 0.91 (s, 9 H), 0.90 (s, 9 H), 0.16 (s, 9 H), 0.09 (s, 3 H), 0.08 (s, 3 H), 0.05 (s, 3 H), 0.04 (s, 3 H); ”C NMR (125 MHz, cool.) 6 : 147.4, 143.4, 137.6, 116.9, 114.5, 114.0, 67.5, 77.7, 76.7, 75.9, 74.6, 31 .6, 25.9, 23.6, 22.6, 16.2 (2), 14.1, 0.05, -4.2, -4.7, -4.8, -5.0. 192 TBS-protection of macrocycle (127) to give TBS-ether (133): To a cold (0 °C) solution of alcohol 127 (0.017 g, 0.019 mmol) in CHzClz (0.4 mL) were added 2,6-Iutidine (3 drops) and TBSOTf (4 drops). After stirring for 4 hours, additional 2,6-lutidine (3 drops) and TBSOTf (4 drops) were added. After stirring yet an additional 4 hours at 0 °C, the ice bath was removed and the reaction stirred at room temperature for 4 hours. The reaction was diluted with E120 (6 mL) and washed with water (0.2 mL), a saturated aqueous CuSO4 solution (0.2 mL x 2), water (0.2 mL) and brine (0.2 mL). The organics were dried over MgSO4, filtered and concentrated to give 36 mg of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 18 mg (92%) of fully protected macrocycle 133 as a clear oil. IR (neat, 4 cm"): v : 2957, 2926, 2657, 1709, 1614, 1514, 1464, 1369, 1360, 1302,1248, 1173, 1152, 1082, 1036, 914, 835, 777; [ofigg+16.2° (c 0.80, CHCI3); 1H NMR (500 MHz, CDCI3) 6 : 7.37 (d, J : 15.91 Hz, 1 H), 7.22 (d, J: 8.84 Hz, 2 H), 7.16 (d, J : 8.39 Hz, 2 H), 6.62 (d, J: 8.84 Hz, 2 H), 6.81 (d, J: 8.84 Hz, 2 H), 6.11 (dt, J : 15.92, 6.63 Hz, 1 H), 5.64 (m, 3 H), 5.48 (s, 1 H), 5.47 (s, 1 H), 5.20 (s, 1 H), 4.94 (s, 1 H), 4.83 (s, 1 H), 4.77 (s, 1 H), 4.71 (dd, J: 3.53, 6.19 Hz, 1 H), 4.51 (A80, J: 11.05 Hz, 1 H), 4.47 (ABq, J: 11.05 Hz, 1 H), 4.27 (ABq, J: 11.05 Hz, 1 H), 4.19 (d, J: 4.86 Hz, 1 H), 4.14 (app 1, J= 4.86/6.19 Hz, 1 H), 4.06 (ABq, J 193 : 11.49 Hz, 1 H), 3.78 (s, 6 H), 3.74 (d, J: 4.42 Hz, 1 H) 3.57 (d, J: 4.66 Hz, 1 H), 3.01 (d, J: 6.19 Hz, 2 H), 2.63 (dd, J: 1.77, 6.19 Hz, 1 H), 2.70 - 2.50 (series m, 3 H), 2.16 (m, 2 H), 1.86 (s, 3 H), 1.86 (m, 1 H), 1.50 - 1.20 (series m, 5 H), 1.01 (d, J = 6.63 Hz, 3 H), 0.92 (d, J: 7.07 Hz, 3 H), 0.90 — 0.60 (series m, 21 H), -0.02 (s, 6 H), -0.04 (s, 3 H), -0.04 (s, 3 H); 13c NMR (125 MHz, CDCI3) 6 : 166.6, 158.8, 156.6, 150.4, 146.6, 145.7, 143.5, 136.6, 132.7, 131.6, 131.3, 129.4, 129.1, 128.8, 126.5, 128.1, 116.5, 115.7, 1152,1135, 113.4, 112.1, 63.6, 61 .1, 78.9, 75.9, 75.8, 71.3, 70.2, 61.1, 56.6, 55.2, 39.6, 39.0, 36.7, 35.3, 35.1, 34.6, 26.0, 25.9, 21.1, 20.0, 18.4, 15.9, 15.4, 14.2, -3.6, -4.2, 4.5, -4.7. DDQ deprotection of PMB-macrocycle (133) to give macrocycle dial (134): To a solution of PMB-ether133 (16.4 mg, 0.0164 mmol) in t-BuOH/ aqueous pH=7 buffer/CH20l2 (1 :1 :5) (1 mL) was added DDQ (15 mg, 0.066 mmol). After stirring for 3.5 hours, the red reaction mixture was diluted with CHZCIZ (6 mL) and a saturated aqueous NaHCOa solution (6 mL). The phases were separated. The aqueous phase was extracted with CHzClz (3 mL x 3). The combined organic phases were washed with a saturated aqueous NaHCOa solution (3 mL), water (3 mL) and brine (3 mL), dried over M9804, filtered, and concentrated to give 27 mg of a dark red oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 6.4 mg (52%) of diol 134 as a clear oil. IR (neat, 4 cm"): v : 3567, 2965, 2928, 2857, 1707, 194 1636, 1603, 1464, 1379, 1262, 1154, 1098, 1030, 905, 801; [oE39+15° (c 0.23, CHCI3); 1H NMR (500 MHz, cool.) 6 : 7.54 (d, J: 15.91 Hz, 1 H), 6.14 (m, 1 H), 5.70 (s, 1 H), 5.56 (dt, J: 15.02, 6.63 Hz, 1 H), 5.42 (dd, J: 4.86, 15.02 Hz, 1 H), 5.32 (s, 2 H), 5.23 (s, 1 H), 5.09 (s, 1 H), 4.83 (s, 1 H), 4.74 (s, 1 H), 4.57 (dd, J: 3.53, 7.07 Hz, 1 H), 4.01 (d, J: 2.65 Hz, 1 H), 3.91 (t, J: 3.53 Hz, 1 H), 3.85 (m, 1 H), 3.69 (dd, J: 3.53, 6.10 Hz, 1 H), 3.16 (dABq, J: 15.02, 5.30 Hz, 1 H), 2.90 (dd, J: 2.21, 6.63 Hz, 1 H), 2.65 (dABq, J: 15.02, 8.84 Hz, 1 H), 2.66 (m, 3 H), 2.64 (dd, J: 2.21, 7.51 Hz, 1 H), 2.30 (m, 2 H), 1.99 (s, 3 H), 1.76 (m, 1 H), 1.50 - 1.20 (series m, 5 H), 0.96 (d, J: 7.07 Hz, 3 H), 0.94 (d, J: 7.07 Hz, 3 H), 0.89 (m, 3 H), 0.88 (s, 9 H), 0.65 (s, 9 H), 0.01 (s, 3 H), 002 (6,3 H), -0.04 (s, 3 H), -0.05 (s, 3 H); “‘0 NMR (125 MHz, CD013)8 : Preparation of Z-amphidinolide A (135): To a solution of disilylated macrocycle 134 in THF (0.5 mL) was added dropwise an acetic acid buffered TBAF (1.05:1) solution (0.07 mL, 0.2 M THF, 0.014 mmol). After stirring for 4.5 hours at room temperature, the reaction was directly loaded onto a silica gel (0.5 9) column [hexanes/EtOAc 75%] and eluted with EtOAc to give 3.4 mg of an oil. Purification by flash chromatography on silica gel (0.3 g) [hexanes/EtOAc 75% —) 100%] afforded 1.1 mg (33%) of z-amphidinolide A 135 as a white solid. 1H NMR (500 MHz, cool.) 6 : 7.52 (d, J 195 =15.91 Hz, 1 H), 6.10 (m, 1 H), 5.70 (s, 1 H), 5.68 (m, 1 H), 5.45 (s, 1 H), 5.42 (dd, J: 5.74, 15.63 Hz, 1 H), 5.40 (s, 1 H), 5.35 (s, 1 H), 5.13 (s, 1 H), 4.87 (s, 1 H), 4.73 (s, 1 H), 4.64 (dd, J: 3.09, 6.63 Hz, 1 H), 4.24 (br s, 1 H), 4.14 (br s, 1 H), 4.12 (br s, 1 H), 4.04 (br s, 1 H), 3.09 (dABq, J: 15.02, 5.74 Hz, 1 H), 2.94 (d, J: 8.39 Hz, 1 H), 2.91 (dd, J: 2.21, 6.63 Hz, 1 H), 2.82 (dABq, 14.58, 6.19 Hz, 1 H), 2.63 (m, 3 H), 2.0 (s, 3 H), 1.73 (m, 1 H), 1.50 ~ 1.20 (series m, 5 H), 0.99 (d, J = 6.63 Hz, 3 H), 0.93 (d, J: 7.07 Hz, 3 H), 0.88 (t, J: 7.07 Hz, 3 H); HRMS (Cl) m/2553.3115 [(M + Na)‘; calcd for C31H4607Na, 553.3141]. Preparation of diene (136) via Liebeskind’s coupling: To a cold (0 °C) solution of (E)-vinyl iodide 301“ (0.27 g, 0.31 mmol) in NMP (2.2 mL) was added copper (l) thiophene-2-carboxylate (CuTc) (0.12 g, 0.61 mmol). To this suspension was added a solution of vinyl stannane 125 (0.27 g, 0.31 mmol) in NMP (1.1 mL). After stirring for 15 minutes at 0 °C, the ice bath was removed and the reaction stirred at room temperature until judged complete by TLC analysis (~ 30 minutes). The reaction mixture was diluted with E120 (30 mL) and filtered through a pad of Celite on a glass frit. The green filter cake was washed with Et20 (3x). The yellow filtrate was washed with water (3 mL x 3), a saturated aqueous KF solution (3 mL x 2), and brine (3 mL). The organics were dried over M9304, filtered and concentrated to give 0.60 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel 196 [hexanes/EtOAc 10% —> 15%] to give 0.17 g (62%) of diene 136 as a light yellow oil. IR (neat, 4 cm"): v : 3513, 3077, 2959, 2930, 1715, 1636, 1613, 1588, 1514, 1464, 1361, 1302, 1248, 1173, 1150, 1074, 1036, 914, 835,779; [eggs-2° (c 0.70, CHCla); 1H NMR (500 MHz, cool.) 6 : 7.24 (d, J: 8.39 Hz, 2 H), 7.21 (d, J: 8.84 Hz, 2 H), 6.86 (d, J: 6.39 Hz, 2 H), 6.84 (d, J: 8.39 Hz, 2 H), 6.07 (s, 1 H), 5.90 (m, 2 H), 5.76 (m, 1 H), 5.71 (s, 1 H), 5.50 (m, 1 H), 5.44 (m, 1 H), 5.30 (d, J: 17.23 Hz, 1 H), 5.16 (m, 1 H), 5.10 (s, 1 H), 5.03 (m, 2 H), 4.93 (s, 1 H), 4.83 (s, 1 H), 4.76 (s, 1 H), 4.66 (dd, J: 5.30, 6.19 Hz, 1 H), 4.55 (m, 2 H), 4.34 (t, J: 5.30 Hz, 1 H), 4.30 (ABq, J: 11.93 Hz, 1 H), 4.21 (ABq, J: 11.05 Hz, 1 H), 4.03 (m, 2 H), 3.95 (d, J: 4.86 Hz, 1 H), 3.79 (s, 6 H), 3.0 (m, 2 H), 2.66 (dd, J: 2.21, 6.19 Hz, 1 H), 2.71 (t, J: 7.51 Hz, 2 H), 2.62 (dd, J: 2.21, 7.07 Hz, 1 H), 2.40 (dd, J: 5.74, 8.84 Hz, 1 H), 2.31 (dABq, J: 4.86, 13.70 Hz, 1 H), 2.25 (s, 3 H), 2.06 (m, 1 H), 1.84 (dABq, J: 9.72, 13.70 Hz, 1 H), 1.50 - 1.20 (m, 5 H), 0.97 (d, J: 7.07 Hz, 3 H), 0.92 (d, J: 7.07 Hz, 3 H), 0.86 (t, J: 7.07 Hz, 3 H), 0.84 (s, 9 H), -0.02 (m, 6 H); ”C NMR (75 MHz, CDCI3) 6 : ; HRMS (FAB) m/z 913.5652 [(M + H)+; calcd for cssHmogst 913.5650]. Ring-closing metathesis of diene (136) to give (E)-macrocycle (140): To a slightly refluxing solution of diene 136 (26 mg, 0.029 mmol) in CHZCIQ (25 mL) was added dropwise (~6 hours) a solution of bis(tricyclohexylphosphine) benzylidene ruthenium dichloride (12 mg, 0.014 mmol) in CHzclz (3 mL). After 197 stirring an additional 18 hours at reflux, the reaction was allowed to cool to room temperature and then concentrated to give 43 mg of a black residue. The black residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 8.7 mg (34%) of truncated ketone 137 as an oil and 6 mg (23%) of the recovered diene. 2"” generation catalyst: To a slightly refluxing solution of diene 136 (20 mg, 0.022 mmol) in CH20I2 (20 mL) was added dropwise (~8 hours) a solution of PhHC:Ru(PCy3)(lMes- H2)Cl2 (19 mg, 0.022 mmol) in CH20I2 (5 mL). After stirring an additional 10 hours at reflux, the reaction was allowed to cool to room temperature and then concentrated to give 34 mg of a black residue. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 7 mg (36%) of macrocycle 140. macrocycle 136: : IR (neat, 4 cm"): v : 3515, 2957, 2930, 2857, 1709, 1636, 1613, 1514, 1464, 1381, 1302, 1248, 1173, 1154, 1074, 1038, 909, 835, 777; HRMS (FAB) m/z 907.5197 [(M + Na)*; calcd for CsaHmOoSiNa, 907.5156]. ketone 137: IR (neat, 4 cm"): v = 2957,2930, 2857, 1715, 1636, 1613, 1514, 1464, 1389, 1358, 1302, 1250, 1173, 1150, 1074, 1038, 912, 835,777; 1H NMR (500 MHz, CDCIa) 8 : 7.20 (d, J: 8.84 Hz, 2 H), 7.19 (d, J = 8.84 Hz, 2 H), 6.86 (d, J: 8.84 Hz, 2 H), 6.83 (d, J: 8.39 Hz, 2 H), 6.05 (m, 2 H), 5.76 (m, 1 H), 5.72 (s, 1 H), 5.63 (s, 1 H), 5.40 (s, 1 H), 5.01 (m, 3 H), 4.83 (s, 1 H), 4.82 (s, 1 H), 4.76 (s, 1 H), 4.66 (dd, J: 4.86, 6.19 Hz, 1 H), 4.43 (ABq, J: 11.49 Hz, 1 H), 4.36 (ABq, J: 11.49 Hz, 1 H), 4.32 (m, 2 H), 4.23 (d, J: 5.74 Hz, 1 H), 4.13 198 (ABq, J: 11.05 Hz, 1 H), 3.94 (d, J: 5.30 Hz, 1 H), 3.78 (s, 6 H), 2.95 (m, 1 H), 2.88 (dd, J: 2.21, 6.19 Hz, 1 H), 2.86 (m, 1 H), 2.71 (t, J: 7.51 Hz, 2 H), 2.62 (dd, J: 2.21, 7.51 Hz, 1 H), 2.31 (dABq, J: 4.42, 13.70 Hz, 1 H), 2.24 (s, 3 H), 2.12 (s, 3 H), 2.05 (m, 1 H), 1.83 (dABq, J: 10.16, 13.70 Hz, 1 H), 1.50 ~1.20 (series m, 5 H), 0.96 (d, J: 7.07 Hz, 3 H), 0.92 (d, J = 7.07 Hz, 3 H), 0.88 (t, J = 7.07 Hz, 3 H), 0.84 (s, 9 H), -0.03 (s, 3 H), -0.05 (s, 3 H); HRMS (Cl) m/z 203.1280 [(M + H)*; calcd for C(0H1904, 203.1283]. Preparation of TMS-ether (138): To a cold (0 °C) solution of diene 136 (0.017 g, 0.019 mmol) in CH20l2 (0.3 mL) were added 2,6-lutidine (2 drops) and TMSOTf (2 drops). After stirring for 3.5 hours, additional 2,6-lutidine (2 drops) and TMSOTf (2 drops) were added. After stirring an additional 10 hours at 0 °C, the reaction was diluted with Et20 (5 mL) and washed with water (0.2 mL), a saturated aqueous CuSO4 solution (0.2 mL x 2), water (0.2 mL x 2) and brine (0.2 mL). The organics were dried over NaQSO4, filtered and concentrated to give 13 mg (70%) of crude TMS-ether138 as a yellow oil. Ring-closing metathesis of diene (138) to give dimer (139): 199 139 2 To a slightly refluxing solution of diene 138 (13 mg, 0.013 mmol) in CHgClz (11 mL) was added dropwise (~5.5 hours) a solution of PhHC=Ru(PCy3)(IMes- H2)Cl2 (4 mg, 0.004 mmol) in CHzclz (2 mL). After stirring an additional 14 hours at reflux, the reaction was allowed to cool to room temperature and then concentrated to give 22 mg of a black residue. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 10 mg (79%) of dimer 139. TBS-protection of macrocycle (140) to give TBS-ether (141): 141 To a cold (0 °C) solution of alcohol 140 (0.021 g, 0.024 mmol) in CH20I2 (0.6 mL) were added 2,6-lutidine (6 drops) and TBSOTf (6 drops). After stirring for 7.5 hours, additional 2,6-Iutidine (3 drops) and TBSOTf (3 drops) were added. After stirring an additional 60 minutes, the reaction was diluted with EtZO (8 mL) and washed with water (0.5 mL), a saturated aqueous CuSO4 solution (0.5 mL x 2), water (0.5 mL) and brine (0.5 mL). The organics were dried over MgSO4, filtered and concentrated to give 59 mg of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 21 mg (90%) of fully 200 protected macrocycle 141 as a clear oil. IR (neat, 4 cm"): v : 2957, 2928, 2857, 1709, 1614, 1514, 1464, 1389, 1360, 1302, 1248, 1173, 1152, 1082, 1038, 914, 835, 777; 1H NMR (500 MHz, cool.) 6 = 7.26 (d, J : 8.39 Hz, 1 H), 7.19 (d, J: 8.39 Hz, 1 H), 7.18 (d, J: 8.39 Hz, 1 H), 7.15 (d, J: 8.39 Hz, 1 H), 6.85 (d, J: 8.84 Hz, 1 H), 6.83 (d, J: 8.84 Hz, 1 H), 6.78 (d, J: 8.84 Hz, 1 H), 6.76 (d, J: 8.39 Hz, 1 H), 5.96 (m, 1 H), 5.92 (d, J: 15.46 Hz, 1 H), 5.65 (s, 1 H), 5.57 (dd, J = 7.51, 15.46 Hz, 1 H), 5.57 (s, 1 H), 5.54 (s, 1 H), 5.46 (m, 1 H), 5.36 (s, 1 H), 5.14 (s, 1 H), 5.0 (s, 1 H), 4.95 (s, 1 H), 4.73 (d, J: 6.63 Hz, 1 H), 4.59 (ABq, J: 11.49 Hz, 1 H), 4.50 (m, 3 H), 4.41 (ABq, J: 11.49 Hz, 1 H), 4.32 (d, J: 5.30 Hz, 1 H), 4.31 (ABq, J: 12.37 Hz, 1 H), 4.14 (d, J: 6.63 Hz, 1 H), 4.13 (ABq, J: 12.37 Hz, 1 H), 4.05 (dd, J: 2.21, 7.07 Hz, 1 H), 3.56 (d, J: 6.63 Hz, 1 H), 3.36 (s, 1 H), 3.0 (dABq, J: 9.26, 14.14 Hz, 1 H), 2.96 (dd, J: 2.21, 7.07 Hz, 1 H), 2.65 (m, 2 H), 2.70 (dd, J: 2.21, 7.51 Hz, 1 H), 2.53 (m, 2 H), 2.47 (dABq, J: 4.86, 13.25 Hz, 1 H), 2.16 (m, 1 H), 2.05 (6,3 H), 1.86 (dABq, J: 7.95, 13.25 Hz, 1 H), 1.50 ~ 1.20 (series m, 4 H), 1.01 (d, J: 7.07 Hz, 3 H), 0.97 (d, J: 6.63 Hz, 3 H), 0.90 — 0.80 (series m, 21 H), 007 (series 6, 12 H); HRMS (CI) m/z 203.1280 [(M + H)*; calcd for C10H1904, 203.1283]. DDQ deprotection of PMB-macrocycle (141) to give macrocycle dial (142): To a solution of PMB-ether141 (21 mg, 0.021 mmol) in f-BuOH/ aqueous pH=7 buffer/CHZCIZ (1 :1 :5) (1.6 mL) was added DDQ (19 mg, 0.086 mmol). After 201 stirring for 3.5 hours, the red reaction mixture was diluted with CHzClz (6 mL) and a saturated aqueous NaHCOa solution (6 mL). The phases were separated. The aqueous phase was extracted with CHZCIZ (2.5 mL x 3). The combined organic phases were washed with a saturated aqueous NaHCOa solution (3 mL), water (3 mL) and brine (3 mL), dried over MgSO4, filtered, and concentrated to give 25 mg of a dark red oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 4.6 mg (52%) of diol 142 as a clear oil. IR (neat, 4 cm"): v : 3567, 2965, 2928,2857, 1707, 1636, 1603, 1464, 1379, 1262, 1154, 1098, 1030, 905, 801; 1H NMR (500 MHz, cock.) 6 : 6.17 (d, J: 15.91 Hz, 1 H), 6.07 (m, 1 H), 5.78 (s, 1 H), 5.59 (s, 1 H), 5.37 (s, 1 H), 5.34 (s, 1 H), 5.24 (dd, J: 3.53, 15.02 Hz, 1 H), 5.21 (s, 1 H), 5.11 (s, 1 H), 4.78 (s, 1 H), 4.74 (s, 1 H), 4.44 (dd, J: 3.53, 7.51 Hz, 1 H) 4.13 (d, J: 2.65 Hz, 1 H), 4.08 (d, J: 3.53 Hz, 1 H), 3.89 (m, 1 H), 3.57 (d, J: 8.39 Hz, 1 H), 3.09 (m, 1 H), 2.90 (dd, J = 2.21 , 7.51 Hz, 1 H), 2.67 (dd, J: 2.21, 7.51 Hz, 1 H), 2.66 (m, 1 H), 2.53 (dABq, J : 8.84, 15.02 Hz, 1 H), 2.51 (d, J: 7.07 Hz, 1 H), 2.44 (cl, J: 8.39 Hz, 1 H), 2.42 (dABq, J: 4.86, 13.25 Hz, 1 H), 2.27 (s, 3 H), 2.15 (m, 1 H), 1.78 (dABq, J: 8.84, 13.25 Hz, 1 H), 1.50 - 1.20 (series m, 5 H), 0.99 (d, J: 7.07 Hz, 3 H), 0.97 (d, J: 7.07 Hz, 3 H), 0.90 (m, 3 H), 0.90 (s, 9 H), 0.87 (s, 9 H), 0.05 (s, 3 H), 0.02 (s, 3 H), 0.01 (s, 3 H), 0.005 (s, 3 H). Preparation of the assigned structure of amphidinolide A (1): 202 To a solution of disilylated macrocycle 142 (1.8 mg, 0.0024 mmol) in THF (0.2 mL) was added dropwise an acetic acid buffered TBAF (1.05:1) solution (0.05 mL, 0.1 M THF, 0.005 mmol). After stirring for 21 hours at room temperature, the reaction was directly loaded onto a silica gel (0.3 9) column [hexanes/EtOAc 25%, 1% MeOH] and eluted with hexanes/EtOAc (1 :3) to give 0.3 mg (25%) of amphidinolide A (1) as a white solid. HRMS (Cl) m/2553.3115 [(M + Na)*; calcd for CaIstoyNa, 553.3141]. Preparation of bisisopentylidene acetal (143): El El fife CASH V1?“ 143 To a 40 °C slurry of L-arabitol (14.80 g, 97.27 mmol) and CSA (0.70 g, 3.0 mmol) in DMF (15 mL) was added 3,3-dimethoxypentane (29.0 g, 217 mmol) dropwise (~30 minutes). After stirring an additional 6 hours, the reaction was quenched with EtaN (0.5 mL) and then concentrated via rotovap at 60 °C to afford a crude oil. The residue was diluted with 320 (200 mL) and washed with brine (50 mL x 4), dried over MgSO4, filtered and concentrated to give 27.84 g of crude acetal 143 as a clear oil. Preparation of ketone (144): 203 144 To a cold (0 °C) solution of alcohol 143 (3.42 g, 11.9 mmol) in CHZCIZ (40 mL) were added DMSO (7 mL), TEA (9.9 mL, 71.156 mmol) and a suspension of SOs-pyridine in DMSO (10 mL). The ice bath was removed and the reaction stirred at room temperature for 90 minutes and was then quenched with a saturated aqueous NH4CI solution (25 mL) and water (6 mL). EtZO (50 mL) was added, and the phases were separated. The organic phase was washed with brine (15 mL x 2). The combined aqueous phases were extracted with Et20 (15 mL x 2). The combined organics were dried over MgSO4, filtered and concentrated to give 6.02 g of a reddish-yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 2.32 g (68%) of ketone 144 as a yellow oil. IR (neat, 4 cm"): v : 2975, 2944, 2884, 1736, 1464, 1360, 1262, 1201, 1173, 1062, 1061, 912, 799; [11E], -63.6° (c 0.66, CHCI3); 1H NMR (300 MHz, CDCla) 8 : 4.82 (t, J: 7.14 or 7.69 Hz, 2 H), 4.31 (t, J: 7.69 or 6.24 Hz, 2 H), 3.96 (dd, J: 7.14, 8.79 Hz, 2 H), 1.69 (m, 6 H), 0.93 (m, 12 H); 130 NMR (75 MHz, cock.) 6 : 205.3, 114.9, 78.7, 66.2, 29.1, 26.2, 8.2, 8.0; HRMS (CI) m/z 203.1280 [(M + H)“; calcd for C10H1904, 203.1283]. Preparation of alkene (145): 204 To a cold (0 °C) mixture of methyltriphenylphosphonium bromide (15.9 g, 44.5 mmol) in THF (60 mL) was added NaHMDS (36 mL, 1.0 M THF, 36 mmol) dropwise. The ice bath was removed and the reaction stirred at room temperature for 30 minutes. A solution of ketone 144 (8.50 g, 29.7 mmol) in THF (10 mL) was added dropwise and the reaction stirred for 3.5 hours at room temperature. The reaction was quenched by the addition of a saturated aqueous NH4CI solution (10 mL) and water (10 mL). The reaction was diluted 320 (120 mL) and the phases were separated. The aqueous phase was extracted with Et20 (10 mL x 2). The combined organic phases were washed with brine (15 mL), dried over MgSO4, filtered and concentrated to give 13.7 g of a red oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5%] afforded 6.96 g (83%) of alkene 145 as a yellow oil. IR (neat, 4 cm"): v : 2975, 2942, 2662, 1464, 1356, 1271, 1198, 1173, 1132, 1060,1059, 1040, 920; [01 39-63.9° (c 0.90, CHCIa); 1H NMR (300 MHz, cool.) 6 : 5.29 (br s, 2 H), 4.50 (dd, J: 6.04, 8.79 Hz, 2 H), 4.18 (dd, J: 6.04, 7.69 Hz, 2 H), 3.55 (dd, J: 7.69, 8.79 Hz, 2 H), 1.64 (m, 6 H), 0.90 (t, J: 7.69 Hz, 6 H), 0.89 (t, J: 7.69 Hz, 6 H); “’0 NMR (75 MHz, 000.) 6 : 144.6, 112.8, 76.1, 70.0, 29.7, 29.4, 6.1 (2); HRMS (Cl) m/z 203.1280 [(M + H)‘; calcd for C10H19O4, 203.1283]. Hydrolysis of acetal (145) to give tetra-oi (146): HO\/’=\"/K/OH 148 To a solution of bisisopentylidene acetal 145 (6.96 g, 24.5 mmol) in MeOH/CH20I2 (2:1) (250 mL) were added CSA (1.14 g, 4.89 mmol) and water (8 205 mL). The reaction flask was immersed into a preheated oil bath (~40 °C) and the reaction stirred for 8.5 hours. The reaction was allowed to cool to room temperature and then concentrated under high vacuum overnight to give 4.84 g of crude tetra-0| 146 as a yellow oil. Preparation of TIPS-ether (147): QHOH OHOH TIFso\/=\"/'\/orlps TIPSO\/?\U/'\/OH 147 148 To a solution of crude tetra-0| 146 (from above) in CH2Cl2/DMF (1 :1) (180 mL) were added imidazole (6.66 g, 97.9 mmol), DMAP (0.30 g, 2.4 mmol) and TIPSCI (11 mL, 51 mmol). After stirring for 24 hours at room temperature, the reaction was concentrated to give a yellow residue. CHzclz (150 mL) was added to the residue, which was then washed with water (25 mL) and brine (25 mL x 2). The organics were dried over MgSO4, filtered and concentrated to give 15.9 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10% —+ 50%] afforded 7.61 g (68% yield, 2 steps) of TIPS disilylated tetra-0| 147 as a clear oil and 1.61 g (22% yield, 2 steps) of TIPS monosilylated tetra-oi 148 as a white solid. tetra-oi 147: IR (neat, 4 cm"): v : 3422, 2944, 2694, 2667, 1464, 1365, 1260, 1107, 1061, 1015, 920, 884, 601; [a jig-115° (c 0.925, CHCla); 1H NMR (300 MHz, CDCI3) 6 : 5.27 (br s, 2 H), 4.23 (m, 2 H), 3.83 (dd, J: 4.40, 9.89 Hz, 2 H), 3.60 (dd, J: 6.24, 9.89 Hz, 2 H), 3.10 (d, J: 2.75 Hz, -OH), 1.03 (m, 42 H); "’0 NMR (75 MHz, CDCI3) 6 : 146.3, 113.4, 73.4, 67.3, 17.9, 11.9; HRMS (Cl) m/z 203.1280 [(M + H)*; calcd for C(0H1904, 203.1283]. 206 Preparation of fully protected tetra-oi (149): game OPMB TIPSO ’ OTIPS 149 To a solution of tetra-0| 147 (8.20 g, 17.8 mmol) in cyclohexane/CHZClz (1 :1) (180 mL) was added PMB-imidate (20.11 g, 71.18 mmol) and CSA (0.41 g, 1.8 mmol). The reaction flask was immersed into a preheated oil bath (~40 °C). After stirring for 48 hours, additional CSA (0.2 g) and PMB-imidate (3.6 g) were added and the reaction continued to stir an additional 23 hours. The reaction was allowed to cool to room temperature and then quenched with a saturated aqueous NaHCOa solution (8 mL). 320 (200 mL) was added and the phases were separated. The organic phase was washed with a saturated aqueous NaHCOa solution (5 mL x 2) and brine (10 mL). The organics were dried over MgSO4, filtered and concentrated to give a milky white solid. Hexanes were added to the residue. After stirring for several hours, the mixture was filtered and concentrated to give 16 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5%] afforded 6.03 g (48%) of fully protected tetra-0| 149 as a clear oil. 1H NMR (300 MHz, CDCI3) 6 : 7.24 (d, J: 6.24 Hz, 4 H), 6.62 (d, J : 8.24 Hz, 2 H), 6.80 (d, J: 8.79 Hz, 2 H), 5.38 (br s, 2 H), 4.56 (ABq, J = 11.54 Hz, 2 H), 4.37 (ABq, J: 11.54 Hz, 2 H), 3.92 - 3.60 (series m, 12 H), 1.02 (m, 42 H); “’0 NMR (75 MHz, CDCI3) 6 : 158.9, 144.7, 130.8, 129.0, 113.7, 113.5, 80.5, 70.4, 67.0, 55.2, 117.9, 11.9; HRMS (Cl) m/z 203.1280 [(M + H)‘; calcd fOl' C10H1904, 203.1283]. 207 Deprotection of TIPS-ether to give dial (1 50): gFMB PMB HO ’ OH 150 To a solution of TIPS disilylated tetra-0| 149 (6.03 g, 8.61 mmol) in THF (90 mL) was added TBAF (19 mL, 1.0 M THF, 19 mmol) dropwise (~30 minutes). After stirring an additional 2.5 hours, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (10 mL) and water (10 mL). Etzo (200 mL) was added and the phases were separated. The organic phase was washed with brine (10 mL x 2). The combined aqueous phases were extracted with Et20 (10 mL). The combined organics were dried over MgSO4, filtered and concentrated to give 8.2 g of a reddish-yellow oil. IR (neat, 4 cm"): v = 3443, 2926, 1612, 1586, 1514, 1464, 1393, 1302, 1248, 1175, 1034, 818; [6339-963 (c 0.65, CHCla); ‘H NMR (300 MHz, cock.) 6 : 7.22 (d, J: 8.79 Hz, 4 H), 6.86 (d, J: 8.24 Hz, 4 H), 5.48 (s, 2 H), 4.55 (ABq, J: 10.99 Hz, 2 H), 4.27 (ABq, J: 10.99 Hz, 2 H), 3.93 (dd, J: 4.40, 6.59 Hz, 2 H), 3.78 (s, 6 H), 3.58 (m, 4 H), 2.42 (br s, -OH); “‘0 NMR (75 MHz, cool.) 6 : 159.3, 142.7, 129.7, 129.5, 117.2, 113.9, 60.1, 70.5, 65.1, 55.2; HRMS (Cl) 171/22031280 [(M + H)+; calcd for c.0H..o., 203.1283]. Preparation of alcohol (153): 9PMB B PIVO\/T\l£OH 153 To a cold (0 °C) solution of diol 150 (1.12 g, 2.88 mmol) in CHZClz (30 mL) were added pyridine (0.47 mL, 5.8 mmol) and a solution of PivCI (0.36 mL, 2.9 208 mmol) in CH2012 (2 mL) dropwise (~3 minutes). After stirring for 12 hours between 0 °C and room temperature, the reaction was quenched by the addition of water (1 mL) and a saturated aqueous NH4CI solution (1 mL). Et20 (40 mL) was added and the phases were separated. The organic phase was washed with a saturated aqueous CuSO. solution (3 mL x 2), water (3 mL x 2) and brine (4 mL), dried over MgSO... filtered and concentrated to give 1.50 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 35% —-> 75%] afforded 0.71 g (52%) of Piv-ester153, 0.25 g (16%) of the di-pivaloyl derivative and 0.30 g (27%) of recovered diol 150 as oils. For spectroscopic data see below. via fully protected tetra-o! (152): To a solution of TIPS protected alcohol 152 (2.49 g, 3.96 mmol) in THF (35 mL) was added TBAF (4.7 mL, 1.0 M THF, 4.7 mmol) dropwise. After stirring for 2 hours, the reaction was diluted with 320 (85 mL) and water (3 mL), and then the phases were separated. The organic phase was washed with brine (4 mL x 2). The combined aqueous phases were extracted with EtZO. The combined organics were dried over MgSO4, filtered and concentrated to give 3.10 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25% -+ 35%] afforded 1.40 g (75%) of alcohol 153 as a clear oil. IR (neat, 4 cm"): v : 3492, 2965, 2672, 2636, 1726, 1613, 1588, 1514, 1646, 1399, 1364, 1302, 1265, 1250, 1173, 1139, 1073, 1036, 927, 620; [dfigg -82.1° (c 0.78, CHCIa); 1H NMR (300 MHz, cool.) 6 : 7.23 (d, J: 8.79 Hz, 4 H), 6.86 (d, J: 8.79 Hz, 2 H), 6.84 (d, J: 8.79 Hz, 2 H), 5.50 (s, 2 H), 4.55 (ABq, J: 209 11.54 Hz, 1 H), 4.54 (ABq, J: 11.54 Hz, 1 H), 4.33 (ABq, J: 11.54 Hz, 1 H), 4.25 (ABq, J : 11.54, 1 H), 4.14 - 4.07 (m, 2 H), 4.03 - 3.95 (m, 2 H), 3.79 (s, 3 H), 3.78 (s, 3 H), 3.56 (m, 2 H), 2.22 (dd, J: 8.79, 4.94 Hz, 1 H), 1.17 (s, 9 H); 13C NMR (75 MHz, CDCI3) 6 = 178.3, 159.3, 159.2, 142.5, 129.9, 129.8, 129.5, 129.3, 117.2, 113.9, 113.8, 80.0, 70.5, 65.7, 65.3, 60.4, 55.2, 38.7, 27.2; HRMS (CI) m/z 203.1280 [(M + H)‘; calcd for CtoHth... 203.1283]. Pivaloyl protection of tetra-oi (148) to give diprotected tetra-oi (151): OHOH TIPSO ’ OPlv 151 To a cold (0 °C) solution of monosilylated tetra-0| 148 (1.85 g, 6.08 mmol) in CHzclz (60 mL) were added pyridine (0.98 mL, 12 mmol) and a solution of PivCI (0.82 mL, 6.7 mmol) in CH2CI2 (4 mL) dropwise. After stirring for 23 hours between 0 °C and room temperature, the reaction was quenched by the addition of water (1 mL) and a saturated aqueous NH4CI solution (1 mL). 320 (150 mL) was added and the phases were separated. The organic phase was washed with water (5 mL), a saturated aqueous CuSO4 solution (6 mL x 2), water (6 mL x 2) and brine (7 mL), dried over MgSO4, filtered and concentrated to give 3.03 g of a clear oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25 %] afforded 1.91 g (81%) of diprotected tetra-oi 151 as a clear oil, and 0.24 g (13%) of recovered monosilylated tetra-0| 148 as a white solid. For 151: IR (neat, 4 cm"): v : 3430,2965, 2944, 2889, 1732, 1464, 1285, 1262, 1157, 1101, 920, 884, 801; [.Eg, -19.9° (c 0.605, CHCIa); 1H NMR (300 MHz, CDCI3) 6 : 5.22 (s, 1 H), 5.20 (s, 1 H), 4.40 (dd, J: 4.94, 6.04 Hz, 1 H), 4.32 (dd, 210 J : 3.65, 7.69 Hz, 1 H), 4.21 (m, 2 H), 3.80 (dd, J: 3.85, 9.89 Hz, 1 H), 3.66 (dd, J: 7.69, 9.89 Hz, 1 H), 3.10 (br s, -OH), 1.18 (s, 9 H), 1.05 (m, 21 H); "’0 NMR (75 MHz, CDCI3) 6 : 176.7, 146.2, 114.0, 73.6, 71.7, 67.3, 67.1, 38.8, 27.1, 17.9, 11.8; HRMS (Cl) m/z 203.1280 [(M + H)"; calcd for C(0H19O4, 203.1283]. PMB protection of tetra-oi (151) to give fully protected tetra-oi (152): QPMB PMB TIPSO : OPiv 152 To a solution of tetra-0| 151 (1.91 g, 4.92 mmol) in cyclohexane/CH20l2 (1:1) (50 mL) was added PMB-imidate (5.55 g, 19.7 mmol) and CSA (0.11 g, 0.49 mmol). The reaction flask was immersed into a preheated oil bath (~40 °C). After stirring for 50 hours, the reaction was allowed to cool to room temperature and was then quenched with a saturated aqueous NaHCOa solution (6 mL). EtZO (125 mL) was added and the phases were separated. The organic phase was washed with a saturated aqueous NaHCOa solution (6 mL x 2) and brine (6 mL). The organics were dried over MgSO4, filtered and concentrated to give a milky white solid. Hexanes were added to the residue. After stirring for several hours, the mixture was filtered and concentrated to give 5.26 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5%] afforded 2.49 g (81%) of fully protected tetra-0| 152 as a clear oil. 912MB PMB PIvO ‘ H o 154 Preparation of aldehyde (154): 211 To a stirred solution of Doss-Martin periodinane (1.63 g, 3.85 mmol) in CH2CI2 (60 mL) were added pyridine (0.31 mL, 3.9 mmol) and a solution of alcohol 153 (1.40 g, 2.96 mmol) in CH2C|2 (6 mL). After stirring for 45 minutes at room temperature, the reaction was quenched by the addition of a saturated aqueous NaHCOal10°/o aqueous Na2$203 (1 :1) solution (60 mL) and diluted with 820 (300 mL). After stirring for 60 minutes, the phases were separated. The organic phase was washed with water (10 mL), a saturated aqueous CuSO4 solution (10 mL x 2), water (10 mL x 2) and brine (10 mL), dried over N82504, filtered and concentrated to give 1.37 g (98%) of crude aldehyde 154 as a yellow oil. IR (neat, 4 cm"): v : 2963, 2670, 2637, 1730, 1613, 1514, 1464, 1397, 1366, 1283, 1250, 1173, 1157, 1078, 1034.622; [a 3.4190 (c 0.45, CHCI3); 1H NMR (300 MHz, cool.) 6 : 9.51 (d, J: 1.65 Hz, 1 H), 7.23 (d, J: 8.79 Hz, 2 H), 7.19 (d, J: 8.79 Hz, 2 H), 6.65 (d, J: 8.79 Hz, 2 H), 6.63 (d, J: 8.79 Hz, 2 H), 5.51 (s, 1 H), 5.48 (s, 1 H), 4.57 (ABq, J: 11.54 Hz, 1 H), 4.44 (s, 1 H), 4.38 (ABq, J : 11.54 Hz, 1 H), 4.13 ~ 4.22 (m, 3 H), 4.06 ~ 4.12 (m, 2 H), 3.77 (s, 3 H), 3.76 (s, 3 H), 1.15 (s, 9 H); 13c NMR (75 MHz, cost.) 6 = 199.2, 176.2, 159.5, 159.2, 140.3, 129.6, 129.5, 128.7, 1205,1139, 113.7, 84.0, 77.9, 71.0, 70.5, 65.6, 55.2, 38.6, 27.1. Preparation of alcohol (155) ~ Fragment AB coupling: 913MB OPMB TMS WOW H 155 t-BuLi (3.95 mL, 1.5 M pentane, 5.93 mmol) was added dropwise to 820 (15 mL) at ~78 °C. A solution of vinyl bromide B (0.64 g, 3.0 mmol) in 320 (4 212 mL) was added dropwise (~18 minutes) to the t-BuLi solution. After stirring for 10 minutes, MgBl’zOEtzo (3.20 mL, 1.0 M Et20/PhH (3:1), 3.20 mmol) was added and the reaction stirred at ~78 °C for 15 minutes and then at 0 °C for 10 minutes. In a separate flask, to a 0 °C solution of crude aldehyde 154 (0.93 g, 2.0 mmol) in CHzclz (9 mL) was added MgBrZ-EtzO (2.0 mL, 1.0 M Et20/PhH (3:1), 2.0 mmol) and the reaction stirred for several minutes. The Grignard solution was transferred via cannula to the precomplexed aldehyde solution. After stirring for 50 minutes at 0 °C, the reaction was quenched by the addition of a saturated aqueous NH..CI solution (3 mL) and water (1 mL). The reaction was diluted with Et20, stirred for 30 minutes and then the phases were separated. The organic phase was washed with brine (1 mL x 2). The combined aqueous phases were extracted with Et20 (2x). The combined organics were dried over M9804, filtered and concentrated to give 1.5 g of a reddish-yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25%] afforded 0.68 g (57%) of alcohol 155 as a yellow oil. IR (CH0. 4 cm“): v : 3361, 2961, 2917, 2865, 2176, 1727, 1684, 1616, 1514, 1458, 1250, 1154, 1036, 843, 760; [egg-619° (c 0.60, CHCIa); 1H NMR (600 MHz, CDCI3) 6 : 7.22 (d, J: 6.20 Hz, 2 H), 7.19 (d, J : 6.20 Hz, 2 H), 6.65 (d, J: 6.20 Hz, 2 H), 6.84 (d, J: 8.20 Hz, 2 H), 5.58 (s, 1 H), 5.49 (s, 1 H), 5.36 (s, 1 H), 5.20 (s, 3 H), 4.53 (ABq, J: 10.77 Hz, 1 H), 4.51 (ABq, J: 11.02 Hz, 1 H), 4.34 (ABq, J: 11.28 Hz, 1 H), 4.29 (dd, J: 2.31, 11.29 Hz, 1 H), 4.23 (ABq, J: 11.02 Hz, 1 H), 3.97 ~ 4.14 (series m, 2 H), 3.90 (d, J: 5.13 Hz, 1 H), 3.78 (m, 1 H), 3.79 (s, 1 H), 3.78 (s, 3 H), 3.06 (ABq, J: 19.99 Hz, 1 H), 2.92 (ABq, J: 19.99 Hz, 1 H), 2.65 (d, J: 4.36 Hz, 1 H), 1.19 (s, 9 H), 0.13 213 (s, 9 H); "’0 NMR (125 MHz, CDCI3) 6 : 176.4, 159.4, 159.2, 142.7, 142.3, 130.1, 129.6, 129.5, 129.3, 116.8, 114.9, 113.9, 113.6, 103.4, 67.6, 80.1, 76.0, 71 .0, 70.7, 66.0, 55.2, 38.8, 27.2, 23.3, 0.05; HRMS (Cl) m/z 203.1260 [(M + H)+; calcd for C(0H1904, 203.1283]. Preparation of TBS-ether (1 56): 9PMB W TMS PWW OTBS 156 To a cold (0 °C) solution of alcohol 155 (0.445 g, 0.731 mmol) in CHzClz (7 mL) were added 2,6-lutidine (0.10 mL, 0.91 mmol) and TBSOTf (0.19 mL, 0.84 mmol). After stirring for 40 minutes at 0 °C, the reaction was quenched with water (0.3 mL) and a saturated aqueous NH4CI solution (0.3 mL). The reaction was diluted with 820 (25 mL) and the phases were separated. The organic phase was washed with a saturated aqueous CuSO4 solution (0.5 mL x 2), water (0.5 mL x 2) and brine (1 mL), dried over MgSO4, filtered and concentrated to give 0.54 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 0.40 g (77%) of TBS-silylated alcohol 156 as a clear oil. IR (neat, 4 cm"): v : 2955, 2656, 2174, 1720, 1613, 1567, 1514, 1464, 1362, 1302, 1157, 1099, 662, 841; [cEQ,-16.1° (c 0.49, CHCI3); 1H NMR (500 MHz, coon) 6 = 7.23 (d, J: 8.39 Hz, 4 H), 6.84 (d, J : 8.39 Hz, 2 H), 6.83 (d, J: 6.64 Hz, 2 H), 5.52 (t, J: 1.33 Hz, 1 H), 5.35 (s, 1 H), 5.28 (d, J: 1.335 Hz, 1 H), 5.11 (s, 1 H), 4.50 (ABq, J: 11.49 Hz, 1 H), 4.49 (ABq, J : 11.49 Hz, 1 H), 4.41 (d, J = 5.30 Hz, 1 H), 4.32 (ABq, J : 11.05 Hz, 1 H), 4.29 (ABq, J: 11.05 Hz, 1 H), 4.24 (dABq, J= 2.21, 11.93 Hz, 1 H), 4.19 (d, 214 J : 7.51 Hz, 1 H), 3.90 (dABq, J: 7.51, 11.49 Hz, 1 H),3.88 (d, J: 5.30 Hz, 1 H), 3.79 (s, 3 H), 3.78 (s, 3 H), 3.14 (ABq, J: 19.44 Hz, 1 H), 3.05 (ABq, J: 19.88 2, 1 H), 1.19 (s, 9 H), 0.83 (s, 9 H), 0.14 (s, 9 H), -0.02 (s, 6 H); "‘0 NMR (75 MHz, CDCI3) 6 : 178.4, 159.0, 142.9, 142.6, 130.8, 130.4, 129.0(2), 113.7 (2), 104.4, 86.9, 81.0, 76.1, 77.4, 71 .2, 70.9, 66.1, 55.3, 38.8, 27.2, 25.8, 24.4, 18.1, 0.12, -5.1 (2); HRMS (Cl) m/z 203.1280 [(M + H)*; calcd for C10H1904, 203.1283]. Preparation of alcohol (157): 991116 OPMB TMS How 0766 157 To a cold (0 °C) solution of Piv-ester 156 (1.01 g, 1.38 mmol) in THF (14 mL) was added dropwise (~10 minutes) Super-Hydridem (2.9 mL, 1.0 M THF, 2.9 mmol). After stirring for 55 minutes, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (2.9 mL), glycerol (0.87 mL, 0.3 mL/mmol) and water (2.9 mL). The reaction mixture was diluted with 820 (125 mL). After stirring for 60 minutes, the phases were separated. The organic phase was washed with brine (1.5 mL), 0.5 M NaOH (1.5 mL x 2), and brine (1.5 mL). The combined aqueous phases were extracted with 320 (3 mL). The combined organics were dried over MgSO4, filtered and concentrated to give 1.13 g of a clear oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 25%] to give 0.80 g (91%) of alcohol 157 as a clear oil. IR (neat, 4 cm"): v :3455, 2957, 2932, 2897, 2859, 2176, 1613, 1514, 1464, 1302, 1250, 1173, 1096, 1063, 1038, 841,777, 760; [6E]. -22.8° (c 0.61, CHCla); 1H 215 NMR (500 MHz, cool.) 6 : 7.23 (d, J: 8.84 Hz, 2 H), 7.22 (d, J: 8.84 Hz, 2 H), 6.86 (d, J: 8.84 Hz, 2 H), 6.84 (d, J: 8.84 Hz, 2 H), 5.47 (s, 1 H), 5.35 (s, 1 H), 5.30 (s, 1 H), 5.11 (s, 1 H), 4.55 (ABq, J: 11.05 Hz, 1 H), 4.50 (ABq, J: 11.49 Hz, 1 H), 4.40 (d, J: 5.74 Hz, 1 H), 4.29 (ABq, J: 11.49 Hz, 1 H), 4.24 (ABq, J: 11.05 Hz, 1 H), 4.08 (dd, J: 3.09.707 Hz, 1 H), 3.78 (s, 6 H), 3.78 (m, 1 H), 3.63 (m, 1 H), 3.40 (ddd, J: 3.98, 7.07, 11.49 Hz, 1 H), 3.15 (ABq, J: 19.44 Hz, 1 H), 3.05 (ABq, J: 19.44 Hz, 1 H), 2.12 (dd, J: 4.42, 9.29 Hz, 1 H), 0.85 (s, 9 H), 0.15 (s, 9 H), -0.01 (s, 6 H); “*0 NMR (75 MHz, CDCI3) 6 : 159.2, 159.1, 142.9, 142.8, 130.5, 130.3, 129.3, 129.0, 114.5,113.6,113.7, 104.2, 80.7, 80.6, 70.9, 70.7, 64.8, 55.2, 25.6, 24.4, 18.2, 0.08, -5.1; Preparation of aldehyde (158): 9121116 OPMB TMS 0 TBS 158 To a stirred solution of Dess-Martin periodinane (0.69 g, 1.6 mmol) in CHzclz (22 mL) were added pyridine (0.14 mL, 1.6 mmol) and a solution of alcohol 157 (0.80 g, 1.25 mmol) in CH2012 (5 mL). After stirring for 40 minutes at room temperature, the reaction was quenched by the addition of a saturated aqueous NaHCOal10% aqueous Nazszo. (1 :1) solution (24 mL) and diluted with Et20 (125 mL). After stirring for 60 minutes, the phases were separated. The organic phase was washed with water (5 mL), a saturated aqueous CuSO4 solution (5 mL x 2), water (5 mL x 2) and brine (5 mL), dried over Na2804, filtered and concentrated to give 0.79 g (98%) of crude aldehyde 158 as a yellow oil. IR (CHCI3, 4 cm"): v : 2955, 2657, 2174, 1730, 1613, 1566, 1514, 1464, 1362, 216 1304, 1101, 1003, 910, 662, 841; [egg], +56.1° (c 0.40, CHCI3); 1H NMR (600 MHz, cool.) 6 : 9.35 (d, J: 2.31 Hz, 1 H), 7.26 (d, J: 6.46 Hz, 2 H), 7.22 (d, J : 8.46 Hz, 2 H), 6.88 (d, J: 8.46 Hz, 2 H), 6.85 (d, J: 8.46 Hz, 2 H), 5.53 (s, 1 H), 5.43 (s, 1 H), 5.22 (s, 1 H), 5.07 (s, 1 H), 4.55 (ABq, J: 11.28 Hz, 1 H), 4.44 (ABq, J: 11.28 Hz, 1 H), 4.41 (d, J: 5.90 Hz, 1 H), 4.38 (ABq, J: 11.53 Hz, 1 H), 4.35 (s, 1 H), 4.20 (ABq, J: 11.28 Hz, 1 H), 3.93 (d, J: 5.90 Hz, 1 H), 3.81 (s, 3 H), 3.80 (s, 3 H), 3.12 (ABq, J: 19.74 Hz, 1 H), 3.02 (ABq, J: 19.74 Hz, 1 H), 0.84 (s, 9 H), 0.16 (s, 9 H), -0.01 (s, 3 H), 002 (6,3 H); 13c NMR (75 MHz, CDCI3) 6 :199.1, 159.4, 159.0, 142.9, 139.7, 130.3, 1295,1294, 129.2, 117.0, 114.4, 113.9, 113.5, 104.3, 87.0, 84.3, 81.2, 71.6, 70.9, 55.2, 25.6, 24.0, 16.2, 0.08, -5.1, -5.2. Preparation of alcohol (159): gPMB OPMB / TMS W OH TBS 159 To a cold (0 °C) solution of crude aldehyde 158 (0.79 g, 1.2 mmol) in CHZCIZ (20 mL) was added MgBrzoEtgo (1.24 mL, 1.0 M Et20/PhH (3:1), 1.24 mmol). After stirring for 6 minutes, vinyl magnesium bromide (2.5 mL, 1.0 M THF, 2.5 mmol) was added dropwise (~ 12 minutes). After stirring for 60 minutes at 0 °C, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (1.3 mL) and water (1.3 mL). The reaction mixture was diluted with Et20 (40 mL), stirred at room temperature for 30 minutes, and then the phases were separated. The organic phase was washed with brine (1.5 mL x 2). The combined aqueous phases were extracted with Et20. The combined organics 217 were dried over M9804, filtered and concentrated to give 1.0 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 0.51 g (61%) of alcohol 159 as a clear oil. IR (neat, 4 cm"): v : 3552, 2958, 2962, 2900, 2858, 2176, 1614, 1514, 1464, 1362, 1303, 1250, 1173, 1091, 1037, 921,841, 779, 760; [01 39 -6.8° (c 0.325, CHCIa); 1H NMR (500 MHz, CDCI3) 6 : 7.26 (d, J: 6.72 Hz, 2 H), 7.22 (d, J: 6.72 Hz, 2 H), 6.86 (d, J: 8.20 Hz, 4 H), 5.89 (ddd, J: 16.66, 11.02, 5.36 Hz, 1 H), 5.49 (s, 1 H), 5.41 (s, 1 H), 5.32 — 5.29 (m, 2 H), 5.16 (m, 1 H), 5.14 (s , 1 H), 4.54 (ABq, J = 11.53 Hz, 1 H), 4.53 (ABq, J: 10.77 Hz, 1 H), 4.49 (d, J: 4.67 Hz, 1 H), 4.34 (ABq, J: 10.77 Hz, 1 H), 4.21 (ABq, J: 10.77 Hz, 1 H), 4.01 (m, 2 H), 3.91 (d, J : 4.87 Hz, 1 H), 3.79 (s, 6 H), 3.17 (ABq, J: 19.48 Hz, 1 H), 3.10 (ABq, J: 19.46 Hz, 1 H), 2.41 (d, J: 5.90 Hz, -OH), 0.85 (s, 9 H), 0.14 (s, 9 H), 0.00 (s, 3 H), -0.01 (s, 3 H); ”C NMR (125 MHz, cool.) 6 : 159.2, 159.1, 143.1, 142.9, 138.1, 130.5, 130.4, 129.3, 129.1, 128.9, 116.1,114.2, 113.7, 113.6, 104.4, 86.8, 82.0, 80.5, 77.1, 73.5, 71.6, 70.7, 55.2, 25.9, 24.8, 18.3, 14.1, 0.10, -5.0, -5.1. Preparation of 1-bromo-alkyne (160): OPMB gPMB / Br oH 6166 160 TMS-alkyne 159 (0.34 g, 0.51 mmol) was dissolved in acetone (5.5 mL) and NBS (0.11 g, 0.61 mmol) and AgNOa (0.013 g, 0.077 mmol) were added. After stirring for 11 hours the reaction was judged complete by TLC analysis. The reaction was quenched by the addition of water (1 mL) and was then diluted with 820 (35 mL). The phases were separated. The organic phase was 218 washed with brine (1 mL x 2), dried over MgSO... filtered and concentrated to give 0.49 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/ EtOAc 10%] afforded 0.27 g (78%) of I-bromo-alkyne 160 as a clear oil. Preparation of vinyl stannane (161): 9PMB OPMB ’ Sne W “3 6H 0166 161 To a solution of (Ph3P)2PdCI2 (3 mg, 0.004 mmol), Red-Sil (1.4 g, 2.9 mmol, 2.1 mmng), and Bu3$nF (0.25 g, 0.80 mmol) in 320 (6 mL) were added a solution of I-bromo-alkyne 160 (0.245 g, 0.365 mmol) in Et20 (1 mL) and a drop of TBAF (1.0 M THF). After stirring for 2 hours at room temperature, the reaction was filtered through a pad of Celite on a glass frit. The residual Red-Sil was washed several times with 320. The filtrate was dried over MgSO4, filtered, and concentrated to give 0.39 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10% —) 15%] to give 0.233 g (72%) of E-vinyl stannane 161 as a clear oil. IR (neat, 4 cm"): v : 2955, 2928,2855.1613,1514,1464,1361,1302,1250,1173,1084,1040,920,835, 777; [cfigg -2.0° (c 0.67, CHCI3); 1H NMR (600 MHz, CDCI3) 6 : 7.25 (d, J: 8.72 Hz, 2 H), 7.21 (d, J: 6.72 Hz, 2 H), 6.85 (d, J: 8.72 Hz, 2 H), 6.84 (d, J: 6.72 Hz, 2 H), 5.95 — 5.85 (m, 3 H), 5.50 (s, 1 H), 5.45 (s, 1 H), 5.30 (md, J: 10.51 Hz, 1 H), 5.16 (md, J: 10.51 Hz, 1 H), 5.07 (s, 1 H), 4.94 (s, 1 H), 4.56 (ABq, J: 10.77 Hz, 1 H), 4.54 (ABq, J: 10.51 Hz, 1 H), 4.35 (d, J: 5.13 Hz, 1 H), 4.33 (ABq, J: 11.79 Hz, 1 H), 4.19 (ABq, J: 11.02 Hz, 1 H), 4.01 (m, 2 H), 3.91 (d, J 219 : 5.38 Hz, 1 H), 3.79 (s, 6 H), 3.0 (m, 2 H), 2.40 (d, J: 5.64 Hz, 1 H), 1.50 (m, 6 H), 1.30 (m, 6 H), 0.87 (m, 24 H), -0.02 (s, 3 H), -0.03 (s, 3 H); “’0 NMR (125 MHz, CDCI3) 6 :159.2, 159.1, 146.6, 143.2, 138.3,130.7, 130.6, 130.2, 129.3, 129.0, 116.0, 114.2, 113.7, 113.7, 113.1, 81.9, 80.8, 78.0, 73.4, 71.7, 70.7, 55.3, 55.2, 41.5, 29.1, 27.3, 25.9, 16.3, 13.7, 9.4, 49, -5.0; HRMS (CI) m/z 203.1280 [(M + H)”; calcd for C(0H1904, 203.1283]. Preparation of diene (162) via Llebesklnd’s coupling: To a cold (0 °C) solution of (E)-vinyl iodide 301“ (0.23 g, 0.52 mmol) and vinyl stannane 161 (0.23 g, 0.26 mmol) in NMP (3 mL) was added copper (l) thiophene-2-carboxylate (CuTc) (0.10 g, 0.52 mmol). The ice bath was removed and the reaction stirred at room temperature until judged complete by TLC (~40 minutes). The reaction mixture was diluted with 320 (30 mL) and filtered through a pad of Celite on a glass frit. The green filter cake was washed with Et20 (3x). The yellow filtrate was washed with water (3 mL x 3), a saturated aqueous KF solution (3 mL x 2), and brine (3 mL). The combined aqueous phases were extracted with Et20. The organics were dried over MgSOz, filtered and concentrated to give 0.52 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10% —-) 15%] to give 0.15 g (63%) of diene 162 as a clear yellow oil. IR (neat, 4 cm"): v = 3501, 3075, 2957, 2928, 2857, 1715, 1613, 1514, 1464, 1391, 1360, 1302, 1250, 1173, 1150, 220 1076, 1038, 914, 835, 779; [ofigg -6.0° (c 0.415, CHCla); 1H NMR (600 MHz, CDCla) 8 : 7.25 (d, J: 8.72 Hz, 2 H), 7.21 (d, J: 8.72 Hz, 2 H), 6.87 (d, J: 8.46 Hz, 2 H), 6.85 (d, J: 8.46 Hz, 2 H), 6.07 (m, 1 H), 5.89 (m, 2 H), 5.76 (m, 1 H), 5.71 (s, 1 H), 5.52 (s, 1 H), 5.44 (s, 1 H), 5.31 (d, J: 17.17 Hz, 1 H), 5.17 (d, J: 8.97 Hz, 1 H), 5.10 (s, 1 H), 5.03 (m, 2 H), 4.93 (s, 1 H), 4.83 (s, 1 H), 4.76 (s, 1 H), 4.65 (dd, J: 5.13, 6.41 Hz, 1 H), 4.57 (ABq, J: 11.53 Hz, 1 H), 4.54 (ABq, J : 11.02 Hz, 1 H), 4.34 (m, 1 H), 4.30 (ABq, J: 11.53 Hz, 1 H), 4.21 (ABq, J: 11.02 Hz, 1 H), 4.03 (m, 2 H), 3.94 (d, J: 4.61 Hz, 1 H), 3.79 (6,3 H), 3.78 (6,3 H), 3.0 (m, 2 H), 2.88 (dd, J: 2.05, 6.41 Hz, 1 H), 2.71 (dABq, J = 6.41, 15.64 Hz, 1 H), 2.69 (dABq, J: 7.18, 15.36 Hz, 1 H), 2.63 (dd, J: 2.05, 7.43 Hz, 1 H), 2.40 (dABq, J: 5.90, 11.28 Hz, 1 H), 2.31 (m, 1 H), 2.25 (s, 3 H), 2.05 (m, 1 H), 1.83 (dABq, J: 9.99, 13.84 Hz, 1 H), 1.50 - 1.20 (series m, 5 H), 0.96 (d, J: 7.18 Hz, 3 H), 0.92 (d, J: 6.92 Hz, 3 H), 0.88 (t, J: 7.18 Hz, 3 H), 0.84 (s, 9 H), -0.03 (s, 6 H); 13C NMR (125 MHz, CDCI3) 8 : ; HRMS (CI) n1/2203.1280 [(M + l—l)*; calcd for C10H1904, 203.1283]. Ring-closing metathesis of diene (162) to give (E)-macrocycle (163): To a slightly refluxing solution of diene 162 (0.15 g, 0.16 mmol) in CH20I2 (150 mL) was added dropwise (~9 hours) a solution of PhHC:Ru(PCy3)(IMes- H2)CI2 (70 mg, 0.082 mmol) in CH20I2 (18 mL). After stirring an additional 15 hours at reflux, the reaction was allowed to cool to room temperature and then 221 concentrated to give 0.26 g of a black residue. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 39 mg (27%) of macrocycle 163. TBS-protection of macrocycle (163) to give TBS-ether (164): To a cold (0 °C) solution of alcohol 163 (0.039 g, 0.044 mmol) in CH20l2 (0.6 mL) were added 2,6-Iutidine (0.02 mL, 0.088 mmol) and TBSOTf (0.013 mL, 0.11 mmol). After stirring for 75 minutes at 0 °C, the reaction was diluted with EtZO (15 mL) and was then washed with water (1 mL), a saturated aqueous CuSO4 solution (1 mL x 2), water (1 mL x 2) and brine (1 mL). The organics were dried over MgSO4, filtered and concentrated to give 75 mg of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 37 mg (82%) of fully protected macrocycle 164 as a clear oil. DDQ deprotection of PMB-macrocycle (164) to give macrocycle diol (165): 165 To a solution of PMB-ether164 (36 mg, 0.037 mmol) in t-BuOH/aqueous pH=7 buffer/CH20I2 (1 :1 :5) (2 mL) was added DDQ (33 mg, 0.15 mmol). After stirring for 4 hours, the red reaction mixture was diluted with CHzclz (12 mL) and a saturated aqueous NaHCOa solution (12 mL). The phases were separated. 222 The aqueous phase was extracted with CH2C|2 (5 mL x 3). The combined organic phases were washed with a saturated aqueous NaHCOs solution (3 mL), water (3 mL) and brine (3 mL), dried over MgSO4, filtered, and concentrated to give 33 mg of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 12 mg (43%) of diol 165 as an oil. Preparation of the amphidinolide A isomer (166): To a solution of TBS-silylated macrocycle 165 (7.8 mg, 0.010 mmol) in THF (1 mL) was added dropwise an acetic acid buffered TBAF solution (1.05:1) (0.11 mL, 0.2 M THF, 0.022 mmol). After stirring for 21 hours, the reaction was directly loaded onto a silica gel (0.4 g) column [hexanes/EtOAc 25%, 1% MeOH] and eluted with hexanes/EtOAc (1:3) to give 2.1 mg of amphidinolide A isomer 166 as a white solid. Preparation of alcohol (167): OPMB gpMe \ i OPlv OH 1 67 To 6 ~23 °C solution of crude aldehyde 110 (0.58 g, 1.24 mmol) in CH2CI2 (18 mL) was added MgBI’QOEtzO (1.36 mL, 1.0 M Eth/PhH 3:1, 1.36 mmol) and allyltributyltin (0.50 mL, 1.6 mmol). The reaction was allowed to warm to 0 °C over 1 hour and then stirred an additional 2 hours at 0 °C. The reaction was 223 quenched by the addition of a saturated aqueous NH4CI solution (1.5 mL) and water (1.5 mL). Etzo (60 mL) was added and the phases were separated. The organic phase was washed with a saturated aqueous KF solution (1.5 mL x 2) and brine (1 mL). The organics were dried over MgSO... filtered and concentrated to give 1.1 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25%] afforded 0.46 g (72%) of alcohol 167 as a clear oil. IR (neat, 4 cm"): v = 3511, 2961, 2936, 2909, 2870, 2838, 1727, 1613, 1514,1479,1464,1397,1302,1282,1250,1173,1157,1064,1036,920,820; [1.1339 +79.0° (c 0.76, CHCI3); 1H NMR (300 MHz, CDCI3) 6 : 7.23 (d, J: 8.24 Hz, 2 H), 7.21 (d, J: 8.79 Hz, 2 H), 6.86 (d, J: 6.24 Hz, 2 H), 6.84 (d, J: 8.79 Hz, 2 H), 5.77 (m, 1 H), 5.58 (s, 1 H), 5.45 (s, 1 H), 5.06 - 4.97 (m, 2 H), 4.56 (ABq, J : 10.99 Hz, 1 H), 4.55 (ABq, J: 11.54 Hz, 1 H), 4.37 (ABq, J: 11.54 Hz, 1 H), 4.22 (ABq, J: 10.99 Hz, 1 H), 4.21 (m, 1 H), 4.10 (m, 2 H), 3.78 (s, 3 H), 3.77 (s, 3 H), 3.72 (d, J: 4.97 Hz, 1 H), 3.64 (m, 1 H), 2.51 (br d, J: 3.30 Hz, 1 H), 2.22 (br t, J: 7.14 Hz, 2 H), 1.16 (s, 9 H); 13c NMR (75 MHz, 00013) 6 = 178.4, 159.4, 159.2, 142.6, 134.7, 130.0, 129.6, 129.3, 116.1, 117.4, 113.9, 113.8, 61.6, 76.7, 71.7, 70.7, 66.1, 55.3, 38.7, 37.7, 27.2; HRMS (FAB) m/2513.2869 [(M + H)+; calcd for CaoH4107, 513.2852]. Preparation of TBS-ether (168): PMB gFMB \ ’ Ova OTBS 166 224 To a cold (0 °C) solution of alcohol 167 (0.46 g, 0.90 mmol) in CHZClz (9 mL) were added 2,6-lutidine (0.14 mL, 1.2 mmol) and TBSOTf (0.23 mL, 0.99 mmol). After stirring for 40 minutes at 0 °C, the reaction was quenched with water (0.5 mL) and a saturated aqueous NH4CI solution (0.5 mL). The reaction was diluted with Et20 (30 mL) and the phases were separated. The organic phase was washed with a saturated aqueous CuSO4 solution (0.5 mL x 2), water (0.5 mL x 2) and brine (1 mL), dried over MgSO4, filtered and concentrated to give 0.63 g of a light pink oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 10%] to give 0.51 g (91%) of TBS- silylated alcohol 168 as a clear oil. IR (neat, 4 cm"): v : 2959, 2934, 2907, 2859, 1730,1613,1514,1464,1302,1284,1250,1173,1155,1101,1067,1038,912, 626, 810, 777; [633, +48.0° (c 0.565, CHCI3); 1H NMR (300 MHz, cool.) 6 : 7.25 (d, J: 8.79 Hz, 2 H), 7.23 (d, J: 6.24 Hz, 2 H), 6.85 (app d, J: 8.24 Hz, 2 H), 6.84 (app d, J: 8.79 Hz, 2 H), 5.85 - 5.71 (m, 1 H), 5.61 (s, 1 H), 5.45 (s, 1 H), 5.01 (m, 1 H), 4.97 (m, 1 H), 4.57 (ABq, J: 10.99 Hz, 1 H), 4.53 (ABq, J: 11.54 Hz, 1 H), 4.37 (m, 1 H), 4.37 (ABq, J: 10.99 Hz, 1 H), 4.22 (ABq, J: 11.54 Hz, 1 H), 4.20 - 4.16 (m, 1 H), 3.96 (dd, J: 7.69, 11.54 Hz, 1 H), 3.84 - 3.76 (m, 2 H), 3.78 (s, 3 H), 3.77 (s, 3 H), 2.4 - 2.3 (m, 1 H), 2.03 (dt, J: 13.73, 6.24 Hz, 1 H), 1.19 (s, 9 H), 0.79 (s, 9 H), -0.03 (s, 3 H), -0.09 (s, 3 H); "’0 NMR (75 MHz, cool.) 6 :178.3, 159.1 (2), 142.4, 135.9,130.6, 1304,1292, 129.1, 11639, 115.1, 113.7, 60.6, 74.5, 70.9, 70.6, 66.1, 55.3, 38.8, 37.5, 27.2, 25.9, 16.1, -4.4, -4.7; HRMS (FAB) m/z 627.3735 [(M -I- H)‘; calcd for C33H550781, 627.3717]. Preparation of alcohol (169): 225 OPMB gFMB \ ‘ OH OTBS 1 69 To a cold (0 °C) solution of Piv-ester168 (0.51 g, 0.812 mmol) in THF (8 ml.) was added dropwise (~12 minutes) Super-Hydride” (1.71 mL, 1.0 M THF, 1.71 mmol). After stirring for 30 minutes, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (1.7 mL), glycerol (0.51 mL, 0.3 mL/mmol) and water (1.7 mL). The reaction mixture was diluted with 820 (60 mL) and stirred for 90 minutes. The phases were separated. The organic phase was washed with 0.5 M NaOH (1 mL x 2), and brine (1 mL). The combined aqueous phases were extracted with Et20 (2 mL). The combined organics were dried over M9304, filtered and concentrated to give 0.52 g of a clear oil. The crude residue was purified by flash chromatography on silica gel [hexanes/ EtOAc 25%] to give 0.40 g (91%) of alcohol 169 as a clear oil. IR (neat, 4 cm"): v : 3468, 2957, 2930,2857, 1613, 1588, 1514, 1464, 1362,1302, 1250, 1173, 1061, 1036, 912, 626, 777; [6339 +56.9° (c 0.37, CHCla); 1H NMR (300 MHz, 00013) 6 : 7.24 (d, J: 8.79 Hz, 2 H), 7.22 (d, J: 8.79 Hz, 2 H), 6.86 (d, J: 8.79 Hz, 2 H), 6.84 (d, J: 8.79 Hz, 2 H), 5.80 (m, 1 H), 5.54 (s, 1 H), 5.42 (s, 1 H), 5.02 (s, 1 H), 4.98 (m, 1 H), 4.60 (ABq, J: 11.12 Hz, 1 H), 4.53 (ABq, J: 11.54 Hz, 1 H), 4.29 (ABq, J: 10.99 Hz, 1 H), 4.25 (ABq, J: 11.40 Hz, 1 H), 4.22 (dd, J: 3.02, 7.69 Hz, 1 H), 3.60 (m, 1 H), 3.79 (s, 3 H), 3.78 (s, 3 H), 3.72 (d, J: 5.06 Hz, 1 H), 3.62 (m, 1 H), 3.43 (ddd, J: 3.65, 7.28, 11.26 Hz, 1 H), 2.35 (m, 1 H), 2.24 (dd, J: 3.85, 9.20 Hz, -OH), 2.06 (tABq, J: 7.63, 14.01 Hz, 1 H), 0.82 (s, 9 H), -0.01 (s, 3 H), -0.09 (s, 3 H); 13c NMR (75 MHz, CDCI3) 6 : 159.2, 226 159.1, 142.7, 135.6, 130.4, 130.2, 129.4, 129.2, 117.0, 115.4, 113.9, 113.7, 81.0, 80.1, 74.2, 70.7, 70.5, 65.2, 55.3, 37.6, 25.9, 18.1, -4.3, -4.7; HRMS (FAB) m/z 543.3130 [(M + H)*; calcd for C31H47068i, 543.3142]. Preparation of aldehyde (170): omeoms \ H OTBS O 1 70 To a stirred solution of Doss-Martin periodinane (0.38 g, 1.6 mmol) in CHzclz (14 mL) were added pyridine (0.070 mL, 0.88 mmol) and a solution of alcohol 169 (0.40 g, 0.74 mmol) in CH20I2 (2 mL). After stirring for 2 hours at room temperature, the reaction was quenched by the addition of a saturated aqueous NaHC03/10% aqueous Nagszoa (1 :1) solution (14 mL) and diluted with Et20 (65 mL). After stirring for 60 minutes, the phases were separated. The organic phase was washed with water (3 mL), a saturated aqueous CuSO4 solution (3 mL x 2), water (3 mL x 2) and brine (3 mL), dried over Na2804, filtered and concentrated to give 0.35 g (88%) of crude aldehyde 170 as a yellow oil. IR (neat, 4 cm"): v : 2955, 2930, 1732, 1613, 1514, 1464, 1362, 1302, 1250, 1173, 1070, 1038, 912, 830, 777; [6339 -29.9° (c 0.50, CHCIa); 1H NMR (300 MHz, cool.) 6 : 9.41 (d, J: 2.20 Hz 1 H), 7.25 (d, J: 8.24 Hz, 2 H), 7.19 (d, J: 8.79 Hz, 2 H), 6.66 (d, J: 8.79 Hz, 2 H), 6.63 (d, J: 8.24 Hz, 2 H), 5.84 - 5.70 (m, 1 H), 5.58 (s, 1 H), 5.48 (s, 1 H), 5.10 - 4.92 (m, 2 H), 4.45 (m, 1 H), 4.57 (ABq, J : 10.99 Hz, 1 H), 4.46 (ABq, J: 10.99 Hz, 1 H), 4.38 (ABq, J: 11.54 Hz, 1 H), 4.13 (ABq, J: 11.54 Hz, 1 H), 3.86 (m, 2 H), 3.79 (s, 3 H), 3.78 (s, 3 H), 2.29 (m, 1 H), 2.02 (m, 1 H), 0.81 (s, 9 H), -0.04 (s, 3 H), -0.07 (s, 3 H); “C NMR (75 227 MHZ, CDCIa) 6 = 199.1, 159.4, 159.1, 140.0, 135.5, 130.2, 129.5, 129.4, 118.1, 117.0, 113.9, 113.6, 84.1, 81.6, 73.7, 71.3, 70.6, 55.2, 37.7, 25.9, 18.1, -4.3, -4.7. Preparation of alcohol (171): OPMB 9PMB TMS W TBS ER 171 t-BuLi (0.98 mL, 1.7 M pentane, 1.7 mmol) was added dropwise to EtzO (4 mL) at ~78 °C. A solution of vinyl bromide B (0.18 g, 0.83 mmol) in Et20 (1 mL) was added dropwise (~7 minutes) to the t-BuLi solution. After stirring for 10 minutes, MngzOEtzo (0.88 mL, 1.0 M Et20/PhH (3:1), 0.88 mmol) was added and the reaction stirred at ~78 °C for 15 minutes and then at 0 °C for 10 minutes. In a separate flask, to a 0 °C solution of crude aldehyde 170 (0.30 g, 0.55 mmol) in CH2Cl2 (3 mL) was added MgBrZ-Etzo (0.55 mL, 1.0 M EtZO/PhH (3:1), 0.55 mmol) and the reaction stirred for several minutes. The Grignard solution was transferred via cannula to the precomplexed aldehyde solution. After stirring for 90 minutes at 0 °C, the reaction was quenched by the addition of a saturated aqueous NH4CI solution (0.4 mL) and water (0.4 mL). The reaction was diluted with E120 (3 mL) and stirred for 30 minutes. The phases were separated. The organic phase was washed with brine (0.5 mL x 2). The combined aqueous phases were extracted with 320. The combined organics were dried over MgSO4, filtered and concentrated to give 0.38 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 0.20 g (53%) of alcohol 171 as a yellow oil. IR (neat, 4 cm"): v : 3553, 2957, 2930, 2857, 2178, 1613, 1514, 1464, 1362, 1302, 1250, 1173, 1062, 1038, 912, 841,777; 228 [4E39 +44.0° (c 0.336, CHCIa); 1H NMR (500 MHz, cool.) 6 : 7.24 (d, J = 8.84 Hz, 2 H), 7.21 (d, J: 8.84 Hz, 2 H), 6.85 (d, J: 8.84 Hz, 4 H), 5.86 (m, 1 H), 5.56 (s, 1 H), 5.52 (s, 1 H), 5.39 (d, J: 1.33 Hz, 1 H), 5.19 (d, J: 1.33 Hz, 1 H), 5.0 (m, 2 H), 4.57 (ABq, J: 11.05 Hz, 1 H), 4.55 (ABq, J: 11.49 Hz, 1 H), 4.26 (ABq, J: 11.05 Hz, 1 H), 4.27 (ABq, J: 11.49 Hz, 1 H), 4.13 (d, J: 3.09 Hz, 1 H), 4.05 (t, J: 4.42 Hz, 1 H), 3.86 (dt, J: 7.51, 4.42 Hz, 1 H), 3.79 (s, 3 H), 3.79 (s, 3 H), 3.75 (d, J: 4.86 Hz, 1 H), 3.09 (ABq, J: 20.32 Hz, 1 H), 2.96 (ABq, J: 20.32 Hz, 1 H), 2.71 (d, J: 5.30 Hz, -OH), 2.42 (m, 1 H), 2.13 (dt, J: 14.14, 7.51 Hz, 1 H), 0.85 (s, 9 H), 0.15 (s, 9 H), 0.01 (s, 3 H), -0.03 (s, 3 H); “C NMR (75 MHz, cool.) 6 :159.3, 159.1, 143.4, 143.2, 135.8, 130.5, 130.1, 129.4, 129.1, 116.9, 115.4, 114.0, 113.8, 113.7, 103.6, 87.9, 61 .0, 80.6, 75.4, 74.6, 71.1, 70.6, 55.3, 37.6, 26.0, 23.5, 18.2, 0.10, -4.1, -4.5; HRMS (FAB) m/z 679.3833 [(M + H)*; calcd for CagHngsSiz, 679.3850]. Preparation of TBS-ether (1 72): OPMB 9PM8 TMS W OTBS 8.1-BS 172 To a cold (0 °C) solution of alcohol 171 (0.198 g, 0.291 mmol) in CHgClg (3 mL) were added 2,6-Iutidine (0.044 mL, 0.38 mmol) and TBSOTf (0.080 mL, 0.35 mmol). After stirring for 30 minutes at 0 °C, the reaction was quenched with water (0.2 mL) and a saturated aqueous NH4CI solution (0.2 mL). The reaction was diluted with EtzO (15 mL) and the phases were separated. The organic phase was washed with a saturated aqueous CuSO4 solution (0.2 mL x 2), water (0.2 mL x 2) and brine (0.4 mL), dried over MgSO4, filtered and concentrated to 229 give 0.29 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 5%] to give 185 mg (80%) of TBS-silylated alcohol 172 as a clear oil. IR (neat, 4 cm"): v : 2957, 2930, 2896, 2857,2178,1614,1588,1514,1472,1302,1250,1173,1094,1040,912,839, 777; [01 239 54° (c 0.40, CHCI3); 1H NMR (500 MHz, cool.) 6 : 7.25 (d, J: 8.84 Hz, 4 H), 6.87 (d, J: 8.84 Hz, 2 H), 6.85 (d, J: 6.39 Hz, 2 H), 5.80 (m, 1 H), 5.48 (s, 1 H), 5.46 (s, 1 H), 5.36 (s, 1 H), 5.16 (s, 1 H), 4.98 (m, 2 H), 4.59 (ABq, J: 11.05 Hz, 1 H), 4.56 (ABq, J: 11.49 Hz, 1 H), 4.42 (ABq, J: 11.05 Hz, 1 H), 4.29 (m, 2 H), 4.14 (d, J: 5.74 Hz, 1 H), 3.89 (dt, J: 7.51, 3.53 Hz, 1 H), 3.64 (d, J : 3.53 Hz, 1 H), 3.80 (s, 3 H), 3.60 (s, 3 H), 3.22 (ABq, J: 20.32 Hz, 1 H), 3.09 (ABq, J: 20.32 Hz, 1 H), 2.45 (m, 1 H), 2.16 (dt, J: 14.14, 7.51 Hz, 1 H), 0.91 (s, 9 H), 0.88 (s, 9 H), 0.15 (s, 9 H), 0.07 (s, 3 H), 0.04 (s, 3 H), 0.03 (s, 3 H), 0.02 (s, 3 H); 13c NMR (125 MHz, cock.) 6 : 159.0, 158.8, 144.4, 143.4, 136.3, 131.4, 131.3, 128.8 (2), 116.7, 115.1, 114.8, 113.6, 113.6, 104.3, 87.5, 82.3, 82.0, 79.1, 74.5, 71.3, 55.2 (2), 37.7, 26.1, 25.4, 24.4, 18.2, 0.10, -4.0, -4.1; HRMS (FAB) m/z 793.4742 [(M + H)‘; calcd for C45H73068i3, 793.4715]. Preparation of bromo-alkyne (173): OPMB gpMB 6r W 0166 6166 173 To a solution of TMS-alkyne 172 (0.14 g, 0.18 mmol) in acetone (2 mL) was added NBS (0.038 g, 0.21 mmol) and AgNOa (0.007 g, 0.04 mmol). After stirring for 7 hours the reaction was judged complete by TLC analysis. The reaction was quenched by the addition of water (0.4 mL) and was then diluted 230 with Et20 (14 mL). The phases were separated. The organic phase was washed with brine (0.4 mL x 2), dried over M9304, filtered and concentrated to give 0.18 g of a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 5%] afforded 92 mg (66%) of 1-bromo-alkyne 173 as a clear oil. IR (neat, 4 cm"): v : 2953, 2928, 2894, 2857, 1613, 1587, 1514, 1464, 1362, 1302, 1248, 1173, 1094, 1040, 1005, 911, 637, 777; [cfigg +1 .3° (c 0.49, CHCI3); 1H NMR (500 MHz, CDCI3) 6 : 7.26 (d, J: 8.84 Hz, 2 H), 7.24 (d, J: 8.39 Hz, 2 H), 6.88 (d, J: 8.84 Hz, 2 H), 6.85 (ABq, J: 8.39 Hz, 2 H), 5.80 (m, 1 H), 5.48 (s, 2 H), 5.33 (d, J = 1.77 Hz, 1 H), 5.15 (s, 1 H), 5.0 (s, 1 H), 4.97 (br d, J: 4.66 Hz, 1 H), 4.59 (ABq, J: 11.05 Hz, 1 H), 4.55 (ABq, J: 11.49 Hz, 1 H), 4.39 (ABq, J: 11.05 Hz, 1 H), 4.26 (ABq, J: 11.49 Hz, 1 H), 4.25 (d, J: 5.74 Hz, 1 H), 4.13 (d, J: 5.74 Hz, 1 H), 3.89 (dt, J: 7.51, 4.42 Hz, 1 H), 3.84 (d, J: 3.98 Hz, 1 H), 3.80 (s, 3 H), 3.80 (s, 3 H), 3.21 (ABq, J: 20.32 Hz, 1 H), 3.05 (ABq, J : 20.32 Hz, 1 H), 2.45 (m, 1 H), 2.17 (dt, J: 14.14, 7.51 Hz, 1 H), 0.90 (s, 9 H), 0.88 (s, 9 H), 0.05 (s, 3 H), 0.04 (s, 3 H), 0.02 (s, 3 H), 0.01 (s, 3 H); 13c NMR (125 MHz, CDCI3) 6 :1590, 156.9, 144.1, 143.3, 136.2, 131.3, 131.2, 126.6(2), 116.7, 115.3, 114.9, 113.7, 113.6, 62.2, 61.9, 79.0, 77.7, 74.5, 71 .2, 55.3, 55.2, 40.6, 37.7, 26.1, 25.9, 24.0, 16.2 (2), 4.1 (2), -4.8, -4.9; Preparation of vinyl stannane (174): OPMB gFMB 0166 6166 174 231 To a mixture of (Ph3P)2PdCl2 (0.8 mg, 0.001 mmol), Red-Sil (0.44 g, 0.92 mmol, 2.1 mmol/9), BuasnF (0.078 g, 0.25 mmol) and 1-bromo-alkyne 173 (0.092 g, 0.12 mmol) in Et20 (2.5 mL) was added a drop of TBAF (1.0 M THF). After stirring for 2 hours at room temperature, the reaction was diluted with 320 (5 mL) and then filtered through a pad of Celite on a glass frit. The residual Red-Sil was washed several times with EtzO. The filtrate was dried over M9804, filtered, and concentrated to give 0.14 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/ EtOAc 2% —+ 5%] to give 74 mg (64%) of E-vinyl stannane 174 as a clear oil. IR (neat, 4 cm"): v = 2955, 2928, 2857,1614,1514,1464,1302,1250,1173,1090,1040,910,837,777; [a 239 -4.5° (C 0.59, CHCI3); 1H NMR (500 MHz, cool.) 6 : 7.23 (d, J: 8.39 Hz, 2 H), 7.21 (d, J : 8.84 Hz, 2 H), 6.84 (d, J: 8.84 Hz, 2 H), 6.83 (d, J: 8.39 Hz, 2 H), 5.91 (m, 2 H), 5.78 (m, 1 H), 5.48 (s, 1 H), 5.44 (s, 1 H), 5.06 (s, 1 H), 4.97 - 4.91 (m, 3 H), 4.59 (ABq, J: 11.05 Hz, 1 H), 4.54 (ABq, J: 11.49 Hz, 1 H), 4.41 (ABq, J : 11.05 Hz, 1 H), 4.24 - 4.20 (series m, 2 H), 4.09 (d, J: 5.74 Hz, 1 H), 3.88 (m, 2 H), 3.79 (6,6 H), 3.06 (ABq, J: 18.56 Hz, 1 H), 2.91 (ABq, J: 18.99 Hz, 1 H), 2.42 (m, 1 H), 2.17 (dt, J: 14.56, 7.07 Hz, 1 H), 1.47 (m, 6 H), 1.27 (m, 6 H), 0.87 (m, 33 H), 0.03 (s, 3 H), 0.02 (s, 3 H), -0.001 (s, 6 H), -0.01 (s, 3 H); “C NMR (75 MHz, cool.) 6 = 156.6, 156.7, 147.7, 146.5, 144.3, 136.3, 131.5, 131.3, 130.2, 128.7(2), 116.7, 115.1, 113.8, 113.6, 113.4, 82.2, 82.0, 79.5, 74.4, 71.1, 71.0, 55.3, 55.2, 41.3, 37.7, 29.1, 27.3, 26.1, 25.9, 18.3, 18.2, 13.7, 9.4, -4.0, -4.7, -4.8; HRMS (FAB) m/z 955.4766 [(M - Bu)"; calcd for csngaossesn 955.4750]. 232 Preparation of diene (175) via Stille cross-coupling: 175 A solution of szdbaa (1.3 mg, 0.0014 mmol) and AsPha (1.8 mg, 0.0058 mmol) in NMP (0.3 mL) were stirred at room temperature for 10 minutes, at which time a solution of (E)-vinyl iodide 30250 (0.035 g, 0.072 mmol) in NMP (0.2 mL) was added to the yellowish-green solution. The reaction flask was immersed into a preheated oil bath (~50 °C) and a solution of vinyl stannane 174 (0.073 g, 0.072 mmol) in NMP (0.2 mL) was added immediately. After stirring for 21 hours at 50 °C, the reaction was allowed to cool to room temperature and was then diluted with 320 (10 mL). The organic phase was washed with water (0.3 mL x 2), a saturated aqueous KF solution (0.3 mL x 2) and brine (0.4 mL). The organics were dried over M9804, filtered and concentrated to give 0.16 g of a yellow oil. The crude residue was purified by flash chromatography on silica gel [hexanes/EtOAc 5%] to give 23 mg (30%) of diene 175 as a clear oil. IR (neat, 4 cm"): v : 2959, 2930,2857, 2176, 1717, 1614, 1587, 1514, 1464, 1388, 1362, 1302, 1250, 1173, 1146, 1094, 1036, 912,839, 777; [a 39 -5.6° (c 0.57, CHCI3); 1H NMR (500 MHz, CDCIa) 6 : 7.23 (d, J: 8.39 Hz, 2 H), 7.21 (d, J: 8.39 Hz, 2 H), 6.85 (d, J: 8.84 Hz, 2 H), 6.84 (d, J: 8.39 Hz, 2 H), 6.04 (m, 2 H), 5.78 (m, 1 H), 5.67 (s, 1 H), 5.48 (s, 2 H), 5.08 (s, 1 H), 4.98 (s, 1 H), 4.96 (m, 1 H), 4.88 (s, 1 H), 4.75 (t, J: 6.19 Hz, 1 H), 4.60 (ABq, J= 11.05 Hz, 1 H), 4.53 (ABq, J: 11.49 Hz, 1 H), 4.37 (ABq, J: 11.05 Hz, 1 H), 4.25 (ABq, J: 11.05 Hz, 1 H), 233 4.21 (d, J: 5.74 Hz, 1 H), 4.13 (d, J: 5.74 Hz, 1 H), 3.90 (m, 2 H), 3.79 (s, 3 H), 3.79 (s, 3 H), 3.05 (dABq, J: 5.74, 16.35 Hz, 1 H), 2.94 (dABq, J: 6.63, 16.35 Hz, 1 H), 2.91 (dd, J: 2.21, 6.19 Hz, 1 H), 2.66 (dd, J: 2.21, 7.51 Hz, 1 H), 2.44 (m, 1 H), 2.40 (dABq, J: 4.86, 16.79 Hz, 1 H), 2.26 (m, 1 H), 2.24 (s, 3 H), 2.18 (dt, J: 14.14, 7.07 Hz, 1 H), 2.07 (m, 1 H), 1.50 ~1.20 (series m, 5 H), 1.11 (d, J : 7.07 Hz, 3 H), 0.93 (d, J: 7.07 Hz, 3 H), 0.88 (m, 12 H), 0.87 (s, 9 H), 0.14 (s, 9 H), 0.03 (s, 6 H), 0.003 (s, 3 H), -0.02 (s, 3 H); “’0 NMR (125 MHz, cool.) 6 : 166.2, 158.9, 158.8, 153.2, 147.4, 144.1, 136.2, 135.4, 135.0, 131.4, 131.2, 126.6, 128.6, 117.6, 116.8, 115.4, 114.3, 113.7, 113.6, 104.7, 86.6, 82.2, 82.1, 79.2, 75.1, 74.5, 71.1 (2), 61 .6, 56.6, 55.3, 37.8, 36.6, 36.3, 35.3, 26.1, 25.9, 23.6, 20.0, 18.3, 16.2, 15.6, 15.3, 14.2, 14.0, 0.06, 4.0, +1.7, -4.8; HRMS (FAB) m/z 1071 .6600[(M + H)"; calcd for c.2Hggo.SIa, 1071.6597]. DDQ deprotection of PMB-ether (174) to give dial (176): OH OH W OTBS OTBS 176 To a solution of PMB-ether174 (40 mg, 0.040 mmol) in t-BuOH/aqueous pH=7 buffer/CHZClz (1 :1 :5) (2 mL) was added DDQ (27 mg, 0.12 mmol). After stirring for 7 hours, the red reaction mixture was diluted with Cchlz (12 mL) and a saturated aqueous NaHCOa solution (12 mL). The phases were separated. The aqueous phase was extracted with 0112012 (5 mL x 3). The combined organic phases were washed with a saturated aqueous NaHCOa solution (10 mL), water (10 mL) and brine (10 mL), dried over M9804, filtered, and concentrated to give 41 mg of a red oil. The crude residue was purified by flash 234 chromatography on silica gel [hexanes/EtOAc 5%] to give 10 mg (53%) of dioI 176 as an oil. Note: the vinyl stannane moiety did not survive the reaction. IR (neat, 4 cm"): v : 3551, 3079, 2955,2930, 2895,2859, 1472, 1464, 1390, 1362, 1255, 1070, 1005, 914, 837, 777; 1H NMR (300 MHz, CDCI3) 6 = 5.77 (m, 2 H), 5.30 (s, 1 H), 5.26 (s, 1 H), 5.11 ~5.03 (series m, 5 H), 4.93 (d, J: 1.33 Hz, 1 H), 4.06 (d, J : 5.30 Hz, 1 H), 3.63 (m, 2 H), 3.76 (dt, J: 7.51, 4.42 Hz, 1 H), 2.89 (d, J: 4.86 Hz, -OH), 2.85 (m, 1 H), 2.74 (d, J: 7.51 Hz, -OH), 2.70 (m, 1 H), 2.43 (dt, J: 14.14, 7.51 Hz, 1 H), 2.23 (m, 1 H), 0.89 (s, 9 H), 0.88 (s, 9 H), 0.07 (s, 3 H), 0.05 (s, 3 H), 0.04 (s, 3 H), 0.01 (s, 3 H); 13c NMR (125 MHz, CDCI3) 6 : 148.5, 147.2, 135.6, 134.2, 118.1, 116.9, 113.6, 113.1, 78.6, 73.9, 73.4, 73.0, 36.9, 36.3, 25.9 (2), 18.2, 18.1, 4.4 (2), -4.5, -5.0; HRMS (FAB) m/z 463.3344 [(M + H)"; calcd for C23H5104$i2, 483.3326]. Preparation of B-iodo ester (177): O O \Vj/\/\/\\\ l/ 177 To a solution of (2)-B-iodo acid 48 (0.50 g, 2.4 mmol) in CH20I2 (5 mL) were added 5-hexyn-1-ol (0.29 mL, 2.6 mmol) and DMAP (0.029 g, 0.24 mmol). The reaction flask was cooled to 0 °C after which a solution of DCC (0.54 g, 2.6 mmol) in CH2012 (1 mL) was added. After stirring for 5 minutes at 0 °C, the ice bath was removed and the reaction continued to stir at room temperature for 6 hours. The reaction mixture was filtered through a pad of Celite on a glass frit. The filter cake was washed with CH20I2 several times. The filtrate was washed with 0.5 M HCI (2 mL x 2) and a saturated aqueous NaHCOa solution (2 mL). 235 The organics were dried over MgSO4, filtered, and concentrated to give 1.05 g of an oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25%] afforded 0.54 g (78%) of (Z)-B-iodo ester 177 as a clear oil. 1H NMR 300 MHz (CDCIa): 6 : 6.27 (d, J : 1.37 Hz, 1 H), 4.15 (t, J : 6.32 Hz, 2 H), 2.70 (d, J : 1.37 Hz, 3 H), 2.20 (dt, J : 2.47, 6.87 Hz, 2 H), 1.93 (t, J = 2.47, 1 H), 1.76 (m, 2 H), 1.59 (m, 2 H); 13c NMR (75 MHz, CDCI3) 6 : 164.3, 125.4, 113.5, 83.8, 68.7, 36.5, 27.6, 24.9, 18.1. lsomerization of 3-octyn-1-ol to 7-octyn-1-ol via “Zipper Reaction”: W" Potassium 3-aminopropylamide (KAPA) was prepared by first washing the KH (8.2 g, 71.32 mmol, 35% mineral dispersion) suspension with hexanes (3x, 5 mL/g of dispersion). The light gray to white solid was cooled to 0 °C and 1,3-diaminopropane (50 mL) was added dropwise and the reaction stirred at 0 °C for 1 hour. The ice bath was removed, and the reaction was stirred at room temperature for 2 hours after which 3-octyn-1-ol (3.0 g, 24 mmol) was added dropwise. After stirring for 8 hours, the reaction was quenched by the slow addition of water (20 mL) and a saturated aqueous NH4CI solution (10 mL). The reaction mixture was further diluted with 1.0 M HCI (20 mL) and 320 (50 mL). The phases were separated. The aqueous phase was extracted with EtZO (50 mL x 3). The combined organics were dried over MgSO4, filtered and concentrated to give a yellow oil. Purification by flash chromatography on silica gel [hexanes/EtOAc 25%] afforded 2.5 g (83%) of 7-octyn-1-ol as a clear oil. 236 1H NMR (300 MHz, cool.) 6 : 3.58 (t, J : 6.59 Hz, 2H), 2.14 (dt, J : 2.74, 6.87 Hz, 2H), 1.90 (t, J : 2.74 Hz, 1H), 1.75 (s, ~OH), 1.5 (m, 4 H), 1.35 (m, 4 H); “‘0 NMR (75 MHz, CDCI3) 6 : 64.5, 68.1, 62.7, 32.5, 26.4, 26.3, 25.2, 16.2. Preparation of vinyl stannane (178): B“33"W\/\/\OH 178 To a solution of 7-octyn-1-ol (0.18 g, 1.4 mmol) in benzene (15 mL) were added AIBN (0.012 g, 0.071 mmol) and Bu3SnH (0.57 mL, 2.1 mmol). The flask was immediately immersed in a preheated ~85 °C oil bath. After stirring for 3 hours, the reaction mixture was concentrated. Purification by flash chromatography on silica gel [hexanes/EtOAc 10%] afforded 0.47 g (79%) of a mixture (4.7:1) of E- and Z-vinyl stannane 178 as a clear oil. Preparation of diene (179) via Stille coupling: 0 CM 4 HO 5/ / 179 To a solution of bis(acetonitrile)palladium (ll) chloride (13 mg, 0.052 mmol) in DMF (10 mL) were added a solution of vinyl iodide 177 (0.30 g, 1.0 mmol) in DMF (0.5 mL) and a solution of vinyl stannane 178 (0.47 g, 1.1 mmol) in DMF (0.5 mL). After stirring for 18 hours at room temperature, the reaction was quenched with the addition of a 10% aqueous NH4OH solution (10 mL). The phases were separated. The aqueous phase was extracted with Et20 (20 mL x 3). The combined organic phases were washed with water (10 mL x 2), brine (10 mL), dried over M9804, filtered, and concentrated to give 0.63 g of a red oil. 237 Purification by flash chromatography on silica gel [Hexanes/EtOAc 25%] afforded 0.11 g (37%) of diene 179 as a yellow oil. ‘H NMR 300 MHz (00013) 6 : 7.53 (dd, J: 0.82, 15.93 Hz, 1 H), 6.10 (dt, J: 15.93, 6.87 Hz, 1 H), 5.57 (d, J: 0.55 Hz, 1 H), 4.09 (t, J: 6.59 Hz, 2 H), 3.60 (dt, J: 5.49 Hz, 2 H), 2.20 (m, 4 H), 1.95 (d, J: 1.1 Hz, 3 H), 1.93 (t, J: 2.75 Hz, 1 H), 1.2 - 1.8 (m, 12 H); 130 NMR 75 MHz (CDCIa) 6 : 166.44, 151.48, 139.11, 127.64, 115.48, 83.89, 68.61, 63.08, 62.79, 33.11, 32.59, 28.89, 28.82. 27.71, 25.45, 24.96, 21.05, 18.03. Preparation of aldehyde (180): 0 CM 4 H 5// O 160 To a solution of alcohol 179 (0.11 g, 0.38 mmol) in Cchlz (4 mL) were added DMSO (0.27 mL, 3.8 mmol), i-PerEt (0.39 mL, 2.3 mmol), and SOs-pyridine (0.18 g, 1.1 mmol) at room temperature. After stirring for 25 minutes, the reaction was quenched by the addition of an aqueous saturated NH4CI solution (4 mL). The reaction mixture was diluted with B20 (12 mL), and the phases were separated. The organic phase was washed with brine (2 mL x 2). The combined aqueous phases were extracted with 320 (3 mL x 2). The combined organics were dried over NaZSO4, filtered, and concentrated to give 0.10 g. The crude product was purified by flash chromatography on silica gel [hexanes/EtOAc 10% —> 25%] to give 57 mg (53%) of aldehyde 180 as a yellow oil. 238 1H NMR 300 MHz (CDCI3): 6 : 9.74 (t, J:1.65 Hz, 1 H), 7.54 (dd, J: 0.82, 15.93 Hz, 1 H), 6.10 (dt, J: 15.93, 6.87 Hz, 1 H), 5.58 (s, 1 H), 4.09 (t, J: 6.59 Hz, 2 H), 2.41(dt, J: 1.65, 7.42 Hz, 2 H), 2.20 (m, 4 H), 1.96 (d, J: 1.1 Hz, 3 H), 1.93 (t, J: 2.75 Hz, 1 H), 1.1 - 1.8 (m, 10 H). Indium cyclization of aldehyde I alkyne (180): Aldehyde-alkyne 180 (57 mg, 0.20 mmol), 1,3-dibromopropene (0.020 mL, 0.196 mmol), indium powder (45 mg, 0.393 mmol), and sodium iodide (59 mg, 0.393 mmol) were added to THF (2 mL). After stirring at room temperature for 6.5 hours, the reaction was quenched with the addition of a saturated aqueous NH4CI solution (0.5 mL). The reaction mixture was diluted with EtZO (4 mL) and the phases were separated. The organic phase was washed with brine (1 mL). The combined aqueous phases were extracted with 320 (2 mL). The combined organics were dried over Nazso. filtered, and concentrated to give 0.090 g of a yellow oil. The crude material was purified by flash chromatography on silica gel [Hexanes/EtOAc 10%] to give two identifiable products in very small quantities. 239 References and Notes: 10. 11. 12. 13. 14. Review: lshibashi, M.; Kobayashi, J. Heterocycles, 1997, 44, 543 - 572. Kobayashi, J.; lshibashi, M.; Nakamura, H.; Ohizumi, Y. 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A.; Trometer, J. D.; Cleary, D. G. Tetrahedron 1989, 45, 391 - 402. Page, P. C. B.; Rayner, C. M.; Sutherland, l. O. J. Chem. Soc. Perkin Trans. 1 1990, 1375 ~ 1382. Payne, G. B. J. Am. Chem. Soc. 1962, 3819 — 3822. Behrens, C. H.; K0, S. Y. K.; Sharpless, K. 8.; Walker, F. J. J. Org. Chem. 1985. 50, 5687 - 5696. Schmid, C. R.; Bradley, D. A. Synthesis 1992, 587 - 590. Mancuso, A. J.; Huang, S. L.; Swem, D. J. Org. Chem. 1978, 43, 2480 ~ 2482. Dess, D. B.; Martin, J. C. J. Am. Chem. Soc. 1991, 113, 7277 ~ 7287. Parikh, J. R.; Doering, W. E. J. Am. Chem. Soc. 1967, 89, 5505 - 5507. Pummerer, R. Chem. Ber. 1909, 42, 2282 — 2291. The regiochemistry of TBS ether 35 was made obvious through the spectroscopic analysis of compounds later in the Scheme such as 29. Tanikaga, R.; Yabuki, Y.; Ono, N.; Kaji, A. Tetrahedron Lett. 1976, 2257 - 2258. Hall, J. A.; Keyworth, D. A. In Brief Chemistry of the Elements with Oualitiative Analysis, Benjamin: Meleno Park, 1971, p.119. Brown, H. C.; Kim, S. 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(b) Abarbri, M.; Parrain, J.; Cintrat, J.; Duchene, A. Synthesis 1996, 82 ~ 86. (a) Rieke, R. D.; Bales, S. E. J. Am. Chem. Soc. 1974, 96, 1775 ~ 1781. (b) Burns, T. P.; Rieke, R. D. J. Org. Chem. 1987, 52, 3674 ~ 3680. Tflckmantel, W.; Oshima, K. ; Nozaki H. Chem. Bar. 1986, 119, 1581 ~ 1593. The aldehyde was not purified because during column chromatography on silica gel the exo-olefin internalized with similar substrates. Smith, A. 3., III; Chen, S. S. Y.; Nelson, F. C.; Reichert, J. M.; Salvatore, B. A. J. Am. Chem. Soc. 1995, 117, 12013 ~ 12014. Nishikawa, T.; Shibuya, S.; Hosokawa, S.; lsobe, M. Synlett1994, 485 ~ 486. (a) Lipshutz, B. H.; Kell, R.; Barton, J. C. Tetrehedron Left. 1992, 33, 5861 ~ 5864. (b) review: Wipf, P.; Jahn, H. Tetrahedron 1996, 52, 12853 — 12909. Kim, S.; Kim, K. H. Tetrahedron Lett. 1995, 36, 3725 — 3728. Allred, G. D.; Liebeskind, L. S. J. Am. Chem. Soc. 1996, 118, 2748 - 2749. Mori, Y.; Yaegashi, K.; Furokawa, H Tetrahedron 1997, 53, 12917 ~ 12932. Takano, S.; Akiyama, M.; Ogasawara, K. Chem. Pharm. Bull. 1984, 32, 791 ~ 794. Kim, K. 8.; Song, Y. H.; Lee, B. H.; Hahn, C. S. J. Org. Chem. 1986, 51, 404 ~ 407. Wang, Z. Tetrahedron Lett. 1989, 30, 6611 ~ 6614. 242 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. The lack of success of this reaction is probably due to the purity of the pivaloyl chloride, and with the success of the silyl protection, the pivaloyl protection was not repeated. (6) Gill, D. M.; Pegg, N. A.; Rayner, C. M. Tetrahedron 1996, 52, 3609 ~ 3630. (b) McIntyre, 8.; Warren, S. Tetrahedron Left. 1990, 31, 3457 ~ 3460. For the synthesis and characterization of this compound see the PhD dissertation of Feng Geng 2001, Michigan State University. Hoye, T. R.; Zhao, H. Org. Lett. 1999, 1, 1123 ~ 1125. - Zhang, S.; Zhang, 0.; Liebeskind, L. S. J. Org. Chem. 1997, 62, 2312 ~ 2313. The lack of identification of the by-products was due to the scale of the k reactions and the contamination of products with residual catalyst. " Garber, S. B.; Kingsbury, J. 8.; Gray, B. L.; Hoveyda, A. H. J. Am. Chem. Soc. 2000, 122, 8168 ~ 8179. For a leading reference see: Furstner, A.; Langemann, K. J. Org. Chem. 1996, 61 . 3942 ~ 3943. The yield of the oxidation was higher if the reaction was ran on a smaller scale (12 mmol or less). This investigation was necessary since no detailed experimental procedure is reported in the literature. (a) Paquette, L.A.; Bennett, G.D.; Isaac, M.B.; Chhatriwalla, A. J. Org. Chem. 1998, 63, 1836 ~ 1845. (b) Paquette, L.A.; Mitzel, T.M.; Isaac, M.B.; Crasto, C.F.; Schomer, W.W. J. Org. Chem. 1997, 62, 4293 ~ 4301. (c) Cintas, P. Synlett, 1995, 1087 ~ 1096. (d) Araki, S.; Shimizu, T.; Johar, P.S.; Jin, S.; Butsugan, Y. J. Org. Chem. 1991, 56, 2538 ~ 2542. Binder, W.H.; Prenner, R.H.; Schmid, W. Tetrahedron, 1994, 50, 749 ~ 758. Ranu, B.C.; Majee, A. J. Chem. Soc, Chem. Commun. 1997, 1225 - 1226. (a) Li, C.; Chen, D. Tetrahedron Lett. 1996, 37, 295 - 298. (b) Araki, S.; Hirashita, T.; Shimizu, H.; Yamannura, H.; Kawai, M.; Butsugan, Y. Tetrahedron Lett. 1996, 37, 8417 — 8420. (0) Li, C. Tetrahedron Lett. 1995, 36, 517 ~ 518. 243 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. Brown, C.A.; Yamashita, A. J. Chem. Soc, Chem. Commun. 1976, 959. Macaulay, S. J. Org. Chem. 1980, 45, 734 — 735. see ref. 6b (a) Miyai, T.; lnoue, K.; Yasuda, M.; Baba, A. Synlett, 1997, 699 ~ 700. (b) Yasuda, M.; Miyai, T.; Shibata, l.; Baba, A. Tetrahedron Lett. 1995, 36, 9497 ~ 9500. (0) Marshall, J. A.; Hinkle, K. W. J. Org. Chem. 1995, 60, 1920 ~ 1921. (a) Terstiege, I.; Maleczka, R. E., Jr. J. Org. Chem. 1999, 64, 342 ~ 343. (b) Maleczka, R. E., Jr.; Terstiege, l. J. Org. Chem. 1998, 63, 9622 ~ 9623. Although successful, reactions carried out in the absence of TBAF or TBAI ran considerably slower. CsF may be substituted for KF with little change in the outcome of the reaction. Some substrate intolerance was observed when 6-(terf-butyldimethyl- silyloxy)-1-hexyne (185) was subjected to conditions A. In this case, although the TBS group remained in place, a significant amount of destannylation occurred. Mitchel, T. N.; Amamria, A.; Killing, H.; Rutschow, D. J. Organomet. Chem. 1986, 304, 257 ~ 265. (a) Lubineau, A.; Augé, J.; Queneau, Y. Synthesis 1994, 741 — 760. (b) Chan, T. H.; Li, C. J.; Lee, M. C.; Wei, Z. Y. Can J. Chem. 1994, 72, 1181 — 1192. (0) Li, C. J. Chem. Rev. 1993, 93, 2023 ~2035. (d) Grieco, P. A. Aldrichimica Acta 1991, 24, 59 ~ 66. (e) Breslow, R. Acc. Chem. Res. 1991,6,159~164. Kawakami, T.; Shibata, l.; Baba, A. J. Org. Chem. 1996, 61, 82 ~ 87. Chuit, C.; Corriu, R. J. P.; Reye, C.; Young, J. C. Chem. Rev. 1993, 93, 1371 ~ 1448. Preliminary 119Sn NMR data is consistent with this hypothesis, as is literature precedent, see Leibner, J. E.; Jacobus, J. J. Org. Chem. 1979, 44, 449 ~ 450. (a) Corey, E. J.; Guzmann-Perexz, A.; Lazerwith, S. E.; J. Am. Chem. Soc. 1997, 119, 11769~ 11776. (b) Pearlman, B. A.; Putt, S. R.; Fleming, J. A. J. Org. Chem. 1985, 50, 3622 ~ 3624. (c) Harpp, D. N.; Gingras, M. J. Am. 244 76. 77. 78. 79. 80. Chem. Soc. 1988, 110, 7737 — 7745. (d) Keck, G. E.; Enholm, E. J.; Yates, J. B.; Wiley, M. R. Tetrahedron 1985, 41, 4079 — 4094. This trend continues when the Buaanl/KF/PMHS method is used under free radical conditions that promote kinetic Z-olefin formation (excess alkyne, short reaction times; Leusink, A. J.; Budding, H. A. J. Organomet. Chem. 1968, 11, 533 - 539; Tolstikov, G. A.; Miftakhov, M. S.; Danilova, N. A.; Vel’der, Y. L. Synthesis 1986, 496 ~ 499; and ref (3b). However, for reasons that remain unclear, the reactions were significantly less selective for the cis vinylstannanes with the BuasnF/TBAF/PMHS protocol. (a) Reed-Mundell, J. J.; Nadkami, D. V.; Kunz, J. M., Jr.; Fry, C. W.; Fry, J. . L. Chem. Mater. 1995, 7, 1655 ~ 1660. (b) Kini, A. D.; Nadkami, D. V.; Fry, J J. L. Tetrahedron Lett. 1994, 35, 1507 ~ 1510. (c) For other immobilized , hydrosilanes, see: Rudzinski, W. E.; Montgomery, T. L.; Frye, J. S.; ' Hawkins, B. L.; Maciel, G. E. J. Catal. 1986, 98, 444 ~ 456. (a) Scott, W. J.; Moretto, A. F. In Encyclopedia of Reagents for Organic Synthesis; Paquette, L. Ed.; Wiley: New York, 1995; Vol. 7, 5327 ~ 5328. (b) Dyer, R. S.; Walsh, T. J.; Wonderlin, W. F.; Bercegeay, M. Neurobehav. Toxicol. Teratol. 1982, 4, 127 ~ 133. At 9-20 mg/kg the LD50 of Meaanl is similar to that of Meaan (7 mg/kg In large rates). However, as a solid (mp 37-38 °C) the Meaanl does not pose the same inhalation hazard as Meaan. Furthermore, the reaction of R38nCI with KF/PMHS initially involves the conversion of the tin chlorides into the corresponding tin fluorides, which given their associated nature are generally only sparingly soluble in organic solvents. Thus, tin poisoning through absorption is also minimized by this protocol. Nakajima, N.; Horita, K.; Abe, R.; Yonemitsu, O. Tetrahedron Lett. 1988, 29, 4139 — 4142. 245 IIIIIIIIIIIIIIIIIIIII 11111111111111]1111111111