PVIESI_J RETURNING MATERIALS: P1ace in book drop to LJBRARJES remove this checkout from ._:—. your record. m3 W‘iH be charged if book—is returned after the date stamped be1ow. PART I STUDIES DIRECTED TOWARD THE SYNTHESIS OF "SUPERTRIPTYCENE" PART II BICYCLO [2.2.2] ALKYNES; REACTIVITY AND THE MECHANISM OF THE TRIMERIZATION By Khalil Shahlai A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of'Chemistry 1987 7 ,.. V / ’7 237’" f" 3 ABSTRACT PART I STUDIES DIRECTED TOWARD THE SYNTHESIS OF "SUPERTRIPTYCENE" PART II BICYCLO [2.2.2] ALKYNES; REACTIVITY AND THE MECHANISM or THE TRIMERIZATION By Khalil Shahlai Fusion of six 9,10-anthradiy1 groups to the six a,c bonds of triptycene would give a hydrocarbon trivially called "supertriptycene" 24. In the first part of this thesis a methodological approach to the synthesis of 24 and related a,c-fused iptycenes in general was explored. The yield of 3-chloro—1,4;1’,4’-di-o—benzeno-l,4,l’,4’-tetrahydro-2,2’- binaphthyl 32, a suitable starting material for such iptycenes, was optimized. Treatment of 32 with two equivalents of n-butyllithium, followed by aqueous quench, gave the parent hydrocarbon 1,4; 1’4 ’-di—o— benzeno~l,4,1’,4’-tetrahydro—2,2’-binaphthyl 56. A Dials-Alder reaction of 56 with 1,2-dichloroethylene, followed by the dehydrochlorination of the cycloadduct, afforded the [1.1.1'.1.l] pentiptycene 2. A similar reaction of 56 with 1,4—epoxynaphtha1ene gave the expected cycloadduct. Dehydration and the subsequent dehydrogenation of this cycloadduct Khal i 1 Shahlai provided an a,c-9,10-anthradiyl bis-fused anthracene, which was converted by reaction with benzyne to the known [1.l.lac.l.l.l.l] heptiptycene 4. Finally a formal bis-adduct of 56 with p-benzoquinone was elaborated to a novel a,c,a’,c’-9,10-anthradiy1 tetrakis—fused anthracene, a potential precursor of 24. In the second part of this thesis, the reactivity and the trimerization mechanism of several bicyclo [2.2.2] alkyne derivatives, generated by the dehydrohalogenation, were studied. Generation of 1,4- dihydro-l,4-ethynonaphthalene 110 in the presence or absence of 1,3- diphenylisobenzofuran (trapping reagent) resulted only in the formation of a 1,3-butadiene coupling product which underwent a novel retro-Diels- Alder reaction. 1,2,3,4—Tetrahydro-1,4-ethynonaphthalene 115, on the other hand, in the presence or absence of a trapping reagent, gave oligomeric products from which an all cis-trimer was isolated. 9- Methyl-Q,lO-ethynoanthracene 122 and 9,lO-dimethyl-Q,lO-ethynoanthracene 133 underwent a Diels-Alder reaction with 1,3-dipheny1isobenzofuran to give the expected cycloadducts. In the absence of the trapping reagent 122 afforded two trimeric products and two 1,3-butadiene coupling products. Attempted trimerization of the bicycloalkyne 133 resulted in the formation of only two coupling products. Based on the experimental results a stepwise mechanism for the trimerization of bicyclo [2.2.2] alkynes, under the mentioned reaction conditions, is proposed. Dedicated to the memory of my father, Ebrahim Shahlai. ii ACKNOWLEDGEMENTS I wish to express my sincerest appreciation and gratitude to Professor Harold Hart for his guidance, encouragement, as well as his endless patience throughout the course of this study. Appreciation is also extended to Michigan State Univeristy and National Science Foundation for financial support in the form of teaching and research assistantships. I would like to thank Professor Bobby A. Howell for his assistance and encouragement during'my initial graduate studies at Central Michigan University. Finally, I am very grateful to my family and friends for their continued help and support in the past few years. iii Chapter TABLE OF CONTENTS LIST OF TABLES. . LIST OF FIGURES . . PART I STUDIES DIRECTED TOWARD THE SYNTHESIS OF "SUPERTRIPTYCENE" INTRODUCTION ......... RESULTS AND DISCUSSION. 1. 10. 11. 12. 13. Improved Synthesis of 3-chloro—1,4; 1’,4’- di-o—benzeno-l,l’,4,4’-tetrahydro- 2,2- binaphthyl 32 ............. Attempted reaction of 32 with 1,4-bisbenzyne. Synthesis of 1,4; 1’,4’-di-o~benzeno-1,l’,3,3’,4,4’- hexahydro-3,3’-binaphthyl- 2,2’-dione 60 ....... Reaction of 32 with 1,2-dichloroethy1ene. Attempted generation of pentiptycyne 67 from 65 . . . . Synthesis of 1’,4’; 7,12-di-o—benzeno- 1’ ,4’, 7, 12-tetrahydro-5, 6-naphthotetraphene- 1, 4—dione 70.. . . . . . . . Synthesis of 1,4; 1’,4’-di-o~benzeno- l,l’4,4’—tetrahydro~2,2’-binaphthy1 56 ........ Reaction of 56 with trans-l,2-dichloroethy1ene. Synthesis of [l.1.1'.l.l] pentiptycene 2. . . . . . . Reaction of 56 with cyclohexene ........... Reaction of 56 with 1,4—epoxynaphtha1ene 38 ..... Dehydrogenation of 76 ..... . . . ..... Synthesis of the heptiptycene 4 ........... iv Page ix 16 17 19 21 22 24 26 28 30 30 31 32 35 Chapter Page 14. Synthesis of 5,14; 8,13-di-o—benzeno—6’,7’- dichloro-5,8,13,14-tetrahydro-6,7- naphthopentaphene 81 ......... . ........ 36 15. Reaction of 56 with 70 ............... . . 37 16. Oxidation of 82 to the anthraquinone derivative 83. . . 40 17. Reduction of i3 ................... . 41 18. Dehydrogenation of 84 ................. 42 EXPERIMENTAL ........................ 47 1. General Procedure ................... 47 2. 3-Chloro-1,4,1’4’-tetrahydro-1,4;l’,4’-di-o- benzeno-Z, 2 ’-binaphthyl, 32 .............. 47 3. 6-Chloro-5,8,13,14-tetrahydro-5,14;8,13-di-o- benzeno-pentaphene, 65 ................. 48 4. 1,4,l’,4’-Tetrahydro-1,4;1’,4’—di-o-benzeno— 2:2’-binaphthy1, 56 .................. 49 5. 6,7-Dichloro-5,6,7,8,13,14-hexahydro- 5,14;8,13-di-o-benzenopentaphene, 73 .......... 49 6. 5,8,13,14-Tetrahydro-5,14;8,13-di-o— benzenopentaphene, 2. . . ............... 50 7. 5,6,7,8,13,14,1’,2’,3’,4’-Decahydro- 5,14;8,13-di-o—benzeno-6,7-benzopentaphene, 74 ..... 50 8. 1’,4’,7,12-Tetrahydro-1,4’;7,12-di-o~ benzeno-5,6-naphthotetraphene-1,4-dione, 70 ...... 51 9. I’ll’lll’llll’1III'4,4I’4II’4III’4IIII-Decahydro_ ll’4l; 111,411; l111,4111’lllll.4lltl_tetra_o_benzeno_ 1,2;3,4;5,6;7,8-tetranaphthoanthra-9,lO-dione, 82 . . . 52 10. 1,1’,1”,1”’,1””,4,4’,4”,4’”,4"LDecahydro- 1 ’,4’; 1",4'; 1 ”’,4”’, 1",4'”-tetra-o~benzeno— 1,2;3,4;5,6;7,8-tetranaphthoanthra-9,10-dione, IR . . . 52 ll. 5,5a,6,7,7a,8,l3,14,1’,4’-decahydro-5,14;8,13- di-o-benzeno-l’,4’-oxo—6,7 naphthopentaphene, 75. . . . 53 12. 5,14;8,l3-Di-o-benzeno-5,5a,7a,8,13,14-hexahydro- 6,7-naphthopentaphene, 76 ............... 53 Chapter 13. 14. 15. 16. 17. 18. 19. 5,14;8,l3-Di-o~benzeno-5,8,13,14-tetrahydro-6,7- naphthopentaphene, 77 .............. 5,5a,6,7,7a,8,13,l4,1’,4’-decahydro-5,14; 8,13-di-o-benzeno—6’,7’-dichloro—1’,4’-oxo—6,7— naphthopentaphene, 79 . . . . . . . . . . ..... 5,14;8,l3-Di-o—benzeno-5,5a,7a,8,13,14-hexahydro- 6’,7’-dichloro-6,7-naphthopentaphene, 80 ....... 5,14;8,13-di-o~benzeno-6’,7’-dichloro—5,8,13,14— tetrahydro-S,7-naphthopentaphene, 81. . . ...... 1,l’,3,3’,4,4’-hexahydro—l,4;l’,4’-di-o— benzeno—S:3-binaphthyl-2,2’-dione, 60 ........ 9,10-Dihydroanthracene Derivative 84. . . ...... Anthracene Derivative 58. . . . . . . . . ...... PART II BICYCLO [2.2.2] ALKYNES; REACTIVITY AND THE MECHANISM OF THE TRIMERIZATION INTRODUCTION. . . . . . . . . . . . ..... RESULTS AND DISCUSSION ......... . ...... l. 10. Reaction of 103 With Iodine . . . . . . . . ..... Reaction of 103 with Methyl Iodide .......... Attempted Generation of a Bicycloalkyne from 103. . . . Attempted Trapping of 110 With 1,3- Diphenylisobenzofuran ..... . . Reduction of 102. ............... Synthesis of 1,2,3,4,5,6,7,8,9,10,11,12- dodecahydro-1,4:5,8:9,lZ—tri-o— benzenotriphenylene (116) . . . ...... Synthesis of 11-ch10ro-9—methy1—9,10— ethenoanthracene (118) and its lZ-chloro isomer (119) ................ Trapping the Cycloalkyne Generated from 118 and 119 by 1,3-dipheny1isobenzofuran . . . . Trimerization of Bridged Bicycloalkyne 122. . . . . . Synthesis of 11-chloro-9,10-dimethy1—9,10- ethenoanthracene (131). ......... . vi Page 54 54 55 56 56 57 58 59 66 67 68 72 73 74 75 77 79 82 Chapter 11. Synthesis of 6,ll-dimethy1-5,12-diphenyl- 5,12-oxo-6,ll—o~benzenonaphthacene 134 ....... 12. Attempted Trimerization of 133. . . EXPERIMENTAL ............... 1. 2-Chloro-3-iodo-l,4-dihydro-l,4- ethenonaphthalene (104) .............. 2. 2-Chloro-3-methy1-1,4-dihydro-1,4- ethenonaphthalene 105 ............... 3. Attempted trapping of 110 with 1,3- diphenylisobenzofuran ....... . . ...... 4. Attempted trimerization of 110. . . . . . . . . . . 5. Thermal decomposition of 2-chloro- 1,4-dihydro-l,4-ethenonaphthalene ......... 6. 2-Chloro-1,4-dihydro-1,4- ethanonaphthalene 114 ............... 7. Attempted trapping of 115 with 1,3-dipheny1 isobenzofuran ................... 8. 1,2,3,4,5,6,7,8,9,10,11,2—Dodecahydro- 1.4.5.8,9.12-tri-o—benzenotripheny1ene 116 ..... 9. ll-chloro-S-methyl-Q,10-ethenoanthracene; 12-chloro-9—methy1-9,10-ethenoanthracene 118 and 119 ......... . . ....... 10. 5,12,-Dipheny1-11-hydro-6emethy1-5.12-oxo- 6,11-0-benzenonaphthacene 123 ...... . 11. Trimerization of the bicycloalkyne 122 generated from 11 and 12-chloro-9-methy1-9,10- ethenoanthracene .................. 12. ll-chloro—S,10-dimethy1-9,10- ethenoanthracene 131 ................ 13. Attempted Trimerization of ll-chloro-9,10- dimethy1-9,10-ethenoanthracene ........... 14. 6,11-Dimethy1-5,12-dipheny1-5,12-oxo-6,ll-o- benzenotetracene 134 ................ vii Page 82 83 86 86 87 87 88 89 90 91 92 93 Chapter 15. 2—Chloro-3-[1-(2-methy1-1-butyne—2-01)]-1,4— dihydro-l,4-ethenonaphtha1ene (109) . . APPENDIX 1. APPENDIX 2. APPENDIX 3. LIST OF REFERENCES. vii Page 96 98 99 107 122 Table Table l . Table 2. Table 3. Table 4. Table 5. LIST OF TABLES Iptycenes derived from triptycene by 9,10-anthradiyl fusions ..... 18 NMR chemical shifts (PPM) of compounds 79, 80, and 81 ............ 13C NMR chemical shifts (PPM) of compounds 79, 80, 81 ...... . . . . . . Bond distances (A) for 66 ......... Bond Angles (0) for 66. . . ix Page 38 39 102 Figure l. End-on view of b,b’,b”-noniptycene 16 ........... 2. Structural representation of "Supertryptycene" 24 3. Crystal structure of compound 66 .............. 4. Stereo drawing of the central ring of the cycloadduct 75 . . 5. Schematic representation of the possible syntheses of iptycenes 17 and 24 from the reaction of anthracene derivatives 77 and 58 with 1,2-dichloroethylene ....... 6. Schematic representation of the possible syntheses of iptycenes 10 and 23 frm the reaction of anthracene derivative 17 and 58 with 1,4-epoxyanthracene. . ...... 7. Structural representation of the isomeric trimers 128 and 125 obtained from the trimerization of the bicycloalkyne 122 . .................. 8. Crystal structure and the packing pattern of the crystals of compound 66 ................... 9. 250 MR2 18 NMR spectrum of compound 60 . . ...... 10. 250 MHz 111 MR spectrum of capound 56 ........... 11. 250 MHz 18 NMR spectrum of [1.1.1'.1.1] pentiptycene 2 . . . 12. 250 MHz 18 NMR spectrum of [1.1.3cbb.1.1] pentiptycene 77. . 13. 250 MHz 111 M spectm of compound 81. 14. 250 MHz 18 NMR spectrum of compound I! ........... 15. 250 MHz 18 NMR spectrum of compound 84 ........... 16. 250 MHz 18 NMR spectrum of compound 58 ........... LIST OF FIGURES Page 14 14 24 33 45 46 101 107 108 109 110 111 112 113 114 Figure Page 17. 250 MHz 13 NMR spectrum of compound 109. . . . . . . . . . . 115 18. 250 MHz 18 NMR spectrum of compound 116. . . . . . . . . . . 116 19. 250 MHz 1H NMR spectrum of compound 123. . . . . . . . . . . 117 20. 250 MHz 18 NMR spectrum of compound 125. . . . . . . . . . . 118 21. 250 MHz 1H NMR spectrum of 1:3 mixture of the isomeric trimers 125 and 128 . . . . . . . . . 119 22. 250 MHz 18 NMR spectrum of the cycloadduct 134 . . . . . . . 120 23. 250 MR2 1H NMR spectrum of the cycloadduct 136 . . . . . . . 121 xi PART I STUDIES DIRECTED TONAHD THE SYNTHESIS OF ”SUPERTRIPTYCENE” INTRODUCTION Triptycene 1, which was first synthesized in 1942,1 is the first member of a large series of compounds now designated as iptycenes, a G) e (9 Despite the substantial number of studies regarding triptycene and general term coined by Bart.2 its derivatives,3 the potential for extending. the rigid framework of this compound to other theoretically interesting and useful iptycenes has only recently been realized.4’5 By fusing one to six 9,10-anthradiyl moieties to the aromatic rings of triptycene, one can derive the first generation of iptycenes. Depending on the number and the site of fusions, twenty four structural variations are possible (Table 1). Only a few of the iptycenes listed in Table 1 are known. A low yield synthesis of 25, a derivative of 2 with two methyl substituents on the central ring, has been reported.2 The synthesis is based on the previously known orthobenzyne bisannelation technique and involves the reaction of the orthodibenzyne Table 1. Iptycenes derived from 1 by 9,10—anthradiyl fusions Point Number Number Fusion Compound Iptycene of fusions of isomers bonds number group prefix O 1 —- 1‘ D 3,, tr(i) 1 2 a 2" C 2,, pent b 3‘ D2,, 2 5 ac 4' D3,, hept aa’ 5 C, ab’ 6 C,“ 30' 7 C2“ bb' 8‘I C2, 3 8 aca’ 9 C,‘ non acb' 10 C, aa’a" 11 C3. aa’b" 12 C, aa'c” 13 C, ab'b" 14 C, ab’c” 15 Cz" bb’b” 16" D3,, 4 5 aca’c' 17 C2, undeca aca’a” 18 C, aca’b" 19 C ,° aca'c” 20 C; acb’b" 21 C2, 5 2 aca’c’a" 22 C, trideca aca’c’b" 23 C2, _ 6 l aca'c’a"c" 24 D 3,, pentadeca 'The parent hydrocarbon is known. I"The ring system is known. ‘ Can exist as a pair of enantiomers. equivalent l,2-dibromo—3,6—diiodo—4,5-dimethylbenzene, with butyl- lithium and two equivalents of anthracene. ., ' 9 @ .1 60 (9 e 325C:H3 Pentiptycene 3 was first prepared through the addition of 2,3- triptycyne to anthracene.7 The overall yield was only 3.7x (crude), since the required starting material 2- bromo—3-fluorotriptycene 26 had to be synthesized from anthracene in four steps (via nitro-, amino-, and 2-bromo-3-aminotriptycene). She :' . Shoo”, e o 26 3 Although not fully aromatic, the pentiptycene quinone 27, which properly belongs to this class of compounds, has been known for a long time and can be readily prepared in high yield from inexpensive precursors, p— benzoquinone and anthracene.8 A much shorter, high yield route to 3 from 1,2,4,5—tetrabromobenzene, anthracene and butyllithium was achieved by Bart and co-workers and was extended to various substituted analogues.9 . s . 0 Br 3' _-_BuLi/TOluene/R.T. g ‘G‘ Br \ Br 6 R G R R z“ ' CngOCHJ A somewhat longer but more useful approach to 3 has recently been developed.2 It involves the addition of benzyne generated from benzenediazonium carboxylate to the triptycene 28. i’ @‘ =>c< 9 Q99 6 6 Huebner, et. al.,1° showed that at -70°C in THF 29 was metalated by n-butyllithium to give the t—lithio derivative 30. Heptiptycene 4 was then reported to be formed as a minor product by heating a solution of 30, presumably via the trimerization of the cycloalkyne 31; the coupling product 32 was also formed. CI -Bu Li /THF Hart and co-workers were able to increase the yield of 4 to 203 by modifying the reaction conditions.2 The synthesis of heptiptycene 8 and noniptycene 16 was success- fully accomplished only recently, through the addition of benzyne to the iptycenes 33 and 34 respectively.1°»11 All of the iptycenes presented in Table 1 contain only benzenoid rings. iNumerous iptycenes with polycyclic aromatic rings such as naphthalene, anthracene, phenanthrene, etc. are known.”-16 Among these the iptycenes with fused anthracenes appear to be viable intermediates in the synthesis of the other iptycenes. Their utility has already been demonstrated in the construction of 3, 8, and 16. Compound 34 can be regarded as the product that would result from the cycloaddition of 2,3-anthryne 35 to 33. Similarly 28 and 33 can be regarded as the cycloadducts of 35 and 2,3:6,7-anthradiyne 36, with one or two equivalents of anthracene respectively. “W *” G) G) . ~I ‘oeeeo'cg “’9 , .. The first reported synthesis of 28 was therefore based on this concept.“» 15 It was originally prepared in 8.48 yield from 37; unfortunately this precursor 37 required five steps for synthesis from toluene. 0 6.3% C02“ iAmONO. dioxone j.@/‘ 0 31 Other approaches to 37 from phthalic anhydride did not represent any advantage over the previous one.1"v18 The potential usefulness of anthracene-fused iptycenes as building blocks for the synthesis of higher analogues therefore demanded shorter synthetic routes with reasonable yields. 2,3—Anthryne and 2,3:6,7~- anthradiyne are not eaSily accessible. However in 1960, Wittig showed that 1,4-epoxynaphthalene 38 was a very effective dienophile.12 It underwent cycloaddition to anthracene to give the corresponding adduct 39, which upon dehydration gave the triptycene 40. some Q as .6 :3... 95% 33 39 40 Thus, 1,4-epoxynaphtha1ene 38 can be considered as a useful 2,3- naphthyne equivalent. Similarly, 1,4-epoxyanthracene 41 and 1,4:5,8- diepoxyanthracene 42 can be regarded as 2,3-anthryne and 2,3:6,7- anthradiyne equivalents, respectively. ”5' ”all 41 42 Both 41 and 42 can be conveniently prepared from l,2,4,5-tetrabromo- benzene.19--22 Treatment with either one or two equivalents of butyllithium in the presence of furan gives 4,5-dibromo—l,4— epoxynaphthalene 43 and 42.23 0 8f 8' leq. BUU. U > Br @w 3‘3, toluene . -23‘e Br 43 Br Br 2 eq. 3“”, 0 > ”a“ Br‘Br taluene. ~23'c 42 Adduct 43, although a useful synthon by itself, can be converted to 2,3- dibromonaphthalene, a precursor to 2,3-naphthyne and consequently to 41. a, Tic1,,2n. _____:m .--..—->. 8r 0 8r“ leq. BULir U > Br toluene. RT ' 4i Availability of valuable synthons such as 41, 42 and 43 has supplemented the synthesis of b-fused type iptycenes. Thus the addition of 43 to anthracene in refluxing xylene gave a single adduct 44 in 96% yield. Dehydration of 44, followed by cycloaddition of the corresponding aryne from 45 to furan and subsequent deoxygenation of the resulting adduct 46 with low valent titanium, provided the iptycene 28 .in four steps and 35% overall yield.4 10 a. 99$ Br- xylene. reflux ; 28 By starting with the three ring precursor 41, the synthesis has been shortened to two steps and an overall yield of 62%. Cycloaddition of 41 to anthracene gave adduct 47 in 93:: yield and acid catalyzed dehydration gave 28.4 663 @3“ xylene. reflux 41 V Complementary to the above routes, 28 has also been synthesized in two steps by the addition of 2,3-naphthyne to diene 48,24 followed by dehydrogenation of the cycloadduct 49. The two steps gave 28 in 73% overall yield.‘ l] @ + :fi BuLl *9 6. __P.‘.‘.’.C_..za @o 49 The diene 48 was found to undergo cycloaddition reactions with a 1,4— dibenzyne equivalent in a similar fashion, to give the cycloadduct 50 which, upon dehydrogenation, provided the iptycene 33 in >80% yield.11 ” s I + 9 9 N 2’ C. 1 Br Br toluene Pd/C 4 33 This procedure proved to be superior to a previous one in which the iptycene 33 had been prepared from the dehydration of bisadduct 51, obtained by adding 1,425,8-diepoxyanthracene 42 to two equivalents of anthracene . 9 669 xylene. reflux 146‘! 42 12 Diene 53, an analog of 48, was synthesized by adding 1,4—dichloro- 2-butene to iptycene 33, followed by dehydrochlorination of the corresponding adduct 52.11 It has been used as the starting material for the construction of 34. As anticipated, diene 53 reacted with 1,4- epoxynaphthalene 38 to give 54. Dehydration of 54 gave 55, which upon dehydrogenation provided 34. CICH,CH=CH CH,CI , ' 200°C .4 days XY'OnOI '“iux 13 Except for compound 4, all of the iptycenes synthesized have been the b-fused type. The remaining iptycenes in Table l have not been reported. Aside from the synthetic challenge, these compounds, along with their derivatives, are likely to possess a number of interesting properties. One of those properties is a high melting point and high thermal stability. For example, the melting points of triphenylmethane, triptycene, pentiptycene 3 and heptiptycene 8 increases from 94°C to 256°C to 483°C to >525°C and the melting point of heptiptycene 4 is reported to be 580°C! The nature of the intermolecular interactions that lead to such high melting points is not obvious. Structural determination by x-ray might provide valuable data regarding the packing patterns of these compounds. By the nature of their rigid frameworks, as well as their high melting points, polyiptycenes could serve as useful shock and heat-resistant materials.” Molecular cavities which could be usefu1 iJi forming host-guest compounds is another interesting feature of these compounds. Iptycene 4 has two equivalent cup—like cavities above and below the central arene ring. Viewed in another sense, it has three equivalent cavities disposed symmetrically above the axes that lie in the plane of the central ring and bisect its non-fused bonds. Heptiptycene 8 has two types of cavities as shown in an end-on view (Figure 1). The larger and more enclosed cavity is U-shaped with two parallel arene rings, whereas the more open cavities are similar to those in 3. 14 or we: End on view b,b’,b”-noniptycene 16. Figure 1. Compound 16 has three analogous U-shaped cavities. Pentadecaiptycene 24 (Figure 2), with the same symmetry as triptycene, has three large cavities symmetrically located around the three Ca axes. @ O . 5.: .9 <9 I e“@ @“3 a, @@‘Q Figure 2. Structural representation of "Supertryptycene" 24. There are six chiral iptycenes listed in Table 1. Three have C2 in which a helical array of axes. Of special interest is iptycene 15, 9,10-anthradiyl moieties are attached to the central triptycene framework, resulting in three helically disposed cavities. Besides the 15 above structural features, iptycenes could also be the subject for other studies such as: organometallic complexes,“ charge transfer complexes,28 novel photochemistry,29 unusual semi-conductor designs and interesting spectral properties related to the ring-ring interactions.30 This work has been aimed at exploring useful routes to a,c—fused iptycenes in general and at synthesizing 24 in particular. The butadiene derivative 32, an undesirable side product in the synthesis of heptiptycene 4, seemed properly suited for the construction of such iptycenes. In the present research, its yield was optimized so that it could be used as a starting material for a,c-fused triptycenes. Although the synthesis of 24 was not achieved, the methodology was successfully applied to the synthesis of iptycenes 2 and 4 and to a promising precursor of 24. RESULTS AND DISCUSS ION From the retrosynthetic point of view, a,c-fused iptycenes can be synthesized by either of the two general routes already developed for their b-fused counterparts.‘ (a) By addition of an ortho-bisaryne to two equivalents of anthracene. (b) Through the cycloaddition reaction between an appropriate dienophile and the butadiene derivative 56, followed by the conversion of the cycloadduct to the final product. Owing to the difficult access to suitable ortho-bisaryne equivalents, and inefficiencies associated with the addition of such bisarynes to anthracene, the first route, though plausible, has limited practical value. It was decided to employ the second route. The butadiene 32 (page 4), a 1-chloro-substituted derivative of 56, was reported to ferm in 393 yield as the by-product in the synthesis of the heptiptycene 4.2 The demand for large quantities of 32 as the starting material and the 16 l7 preemption that 4 was formed by a stepwise pathway in which the 4- lithio-butadiene derivative 57 is an intermediate which, upon quenching with a proton source, leads to 32, prmpted us to explore the possibility of retarding the formation of 4 and therefore optimizing the yield of 32. fig?” *9 31 -Ucu Cmpound 32 has a very low solubility in hexanes. Thus it might be asst-ed that 57, by the virtue of the presence of lithium, would be even less soluble in this solvent and consequently, less available for the reaction with the cycloalkyne 31. 1. Improved Synthesis of 3-chloro—1,4; l’,4’-di—o—benzeno— l,1’,4,4’-tetrahydro-2,2’-binaphthy1 32. The starting material, ll-chloro-9,10-dihydro-9,10-ethenoan- thracene 29, was synthesized according to the literature.31 A l8 suspension of anthracene in trans-1,2—dichloroethylene in a sealed tube was heated at 195-200°C for 48 hours followed by dehydrochlorination of the resulting adduct with potassium t-butoxide in refluxing TRF. Q CI 29 In a typical reaction, 29 was then dissolved in the least amount of a 5:1 mixture of anhydrous hexanes and TRF (this usually corresponded to approximately 25 mL of hexanes and 5 ml. of THF for 10 mol of the substrate) at room temperature. The temperature was lowered to -78°C and 1.1 equivalent of n-butyllithium was added to the resulting suspension. The reaction mixture was stirred for another hour and then gently refluxed for 30 minutes. During the course of the reaction a any black precipitate formed which, upon quenching with methanol, decolorized. The melting point and the 111 mm spectrum of a purified sample of this precipitate were identical to those reported for 32.9 Purification of the codained precipitate and the remaining residue after evaporation of the solvent gave 32 in 75-833 yield. In each reaction, only traces of the heptiptycene 4 were formed. 19 2. Attempted reaction of 32 with 1,4-bisbenzyne. Arynes and bisarynes have been reported to undergo [4+2] A cycloaddition reactions with 1,3—butadienes to form six-meflered ring cycloadducts.32 In the case of acyclic 1,3-butadienes, where rotation around the spa-spa bond is allowed, these reactions usually proceed only in low yields. Such low yields can be attributed to the tendency of these dienes to adopt the thermodynamically more stable s-trans conformation. In spite of this, it was thought that the addition of a 1,4-bisbenzyne equivalent to 32, followed by dehydrochlorination of the expected bisadducts, might provide a short route to the anthracene derivative 58, a potential synthon for the pentadecaiptycene 24. 20 In this regard, two equivalents of n—butyllithium were added to a solution of a 1:2 mixture of l,2,4,5-tetrabromobenzene and 32 in THF at -7BPC. The reaction mixture was allowed to warm to room temperature and stirred for two hours. The 111 1MB spectrum of the reaction mixture after work up did not show the presence of an adduct. Similar reactions with 1,2-dibromobenzene also failed. The failure of 32 to undergo any [4+2] cycloaddition reaction with benzynes urged us to seek other alternatives for the construction of 58. Furans and N-alkylpyrroles, in which the 1,3-diene is constrained to a s-cis conformation might provide such an alternative. Both furans and N-alkylpyrroles undergo cycloaddition reactions with benzynes to give the corresponding cycloadducts in excellent yields.33 Furthermore, the resulting cycloadducts can effectively be converted into aromatic compounds. We therefore undertook the synthesis of the 1,4-diketone derivative 60, anticipating that dehydration of this diketone would provide the desired furan derivative 61 or the Nemethylpyrrole derivative 62. _H20 0‘...- c..- o 21 3. Synthesis of 1,4; 1’,4’-di-o—benzeno—l,l’,3,3’,4,4’- o “a..." now...- The starting material, 1,4-[1’,2’]-benzeno-l,3,4—trihydronaph— thalene-Z-one (59), was prepared in quantitative yield by the solvolysis of 29 in a mixture of glacial acetic acid and concentrated sulfuric acid.“ Using the lithium salt of hexamethyldisilazine as the base, 59 was converted to its enolate.” Oxidative coupling of the enolate was achieved by adding one equivalent of anhydrous ferric chloride in DMF36 to a solution of the enolate in TBF, to give 60 in 63" yield. 1). (Me,Si l2NLi Other known methods for the coupling of enolates did not give satisfactory results.” The diketone 60 was characterized by its mass, 111 m and 13C 101R spectra. The mass spectrum of 60 showed a molecular 22 ion peak at m/e 438. The 1R MIR spectrum showed a two-proton singlet at B 1.73 for the methyne protons a—to the carbonyl groups, two two-proton singlets at 6 4.77 and 5.02 corresponding to the bridgehead protons and four sets of multiplets at 6 7.12-7.46 for the aromatic protons. 13C W showed two peaks at 6 47.25 and 47.55 for the bridgehead carbon atoms, a peak at 5 63.70 for the carbon atoms s—to the carbonyl group, and a peak at 6 205.28 corresponding to the carbonyl carbon atom. Unfortunately, attempts to dehydrate 60 using several known methods did not give satisfactory results.3°'39 In every case the starting material 60 was recovered. Also, heating a solution of so in methyluine at 150°C in a sealed tube failed to give 62,33 but instead gave several products which could not be characterized. With the failure of these routes, therefore cycloadditions of 32 with long-lived dienophiles was tried next . 4. Reaction of 32 with 1,2-dichloroethylene A suspension of 32 in trans—1,2-dichloroethylene was heated at 195-200°C in a sealed tube for 36 hours. Analysis of the tube contents after evaporation of the solvent indicated the absence of the starting material and the presence of two major products, possibly the two isomers and 64 anticipated for the reaction. 23 Dehydrochlorination of the crude mixture, without further purification, using sodium methoxide in refluxing methanol, afforded a single product 65 in 68* yield. 53 + 54 N30 Mel MOO‘H The structure of 65 was confirmed by its mass, 111 “IR and 13C m spectra. The mass spectra showed a molecular ion peak at m/g 467. The ‘11 M spectra showed four one-proton singlets at a 5.28, 5,83, 5.91 and 5.96 for the bridgehead protons, a one-proton singlet at‘ 6 7.03 for the proton next to the chlorine atom on the central ring and four sets of multiplets corresponding to the remaining 16 aromatic protons. The 13C MIR spectra, which showed four distinct peaks with equal intensities for the sp3 hybridized bridgehead carbon atoms, was also consistent with structure 65. When high concentrations of 32 were used in the Diels- Alder reaction with trans-1,2-dichloroethylene, a crystalline compound separated from the reaction mixture. This compound melted at 321°C with gradual decomposition, and was practically insoluble in all organic and inorganic solvents. x-ray crystallography (Figure 3) showed the compound to be 66. Reactions of chlorinated 24 ethylenes at high temperatures are usually accompanied by the formation of considerable amounts of hydrogen chloride. Compound 66 most likely originates from the 1,4-addition of hydrogen chloride to 32. Figure 3. Crystal structure of compound 66. 5. Attempted generation of pentiptycyne 67 from 65 The cycloaddition reactions of arynes and furan have routinely been used to construct polycyclic aromatic compounds. It was anticipated that the reaction of the pentiptycyne 67, generated from 65, could react with furan to provide the cycloadduct 68, a valuable synthon 25 for the synthesis of the anthracene derivative 58, and also a potential precursor of the a,c-fused naphthalenoid iptycene I. Thus a solution of 65 in TBF in the presence of excess furan was treated with n—butyllithium at -78°C. Analysis of the reaction mixture after stirring at room temperature for two hours showed only the starting material 65. Other attempts using harsher conditions, such as refluxing the reaction mixture or treatment with n-butyllithia and potassium t- butoxide as the base, resulted mainly in halogen-metal exchange, and consequently in the formation of pentiptycene 2. 1 s'BuLi 2. H9 65 2 The structure of 2 was confirmed by its 111 MIR and 13C m spectra. The 111 M01 spectra of 2 showed only two two- proton sharp singlets at 5 5.31 and 5.94 for the two sets of bridgehead hydrogens (Czh sy-etry) and three sets of multiplets in the araatic region for the total of 18 protons. The 1“C RI! spectra showed two peaks at 5 50.51 and 54.59 corresponding to the spa bridgehead carbon atom, as expected by the sy-etry of 2, and a total of seven peaks for the sp2 carbon etc. 6. Synthesis of 1 ’, 4 ’; 7 , lZ-di—o—benzeno-l ’ , 4 ’ , 7 L12-tetrahydro— 5,6-naphthotetraphene-1,4-dione 70 p-Benzoquinone adds to one or two equivalents of a 1,3-diene to form either mono- or bis-adducts.“ These adducts can readily be converted to the corresponding hydrocarbons. Thus one equivalent of p- benzoquinone in xylenes was heated at reflux with two equivalents of diene 32 for 24 hours. The two major components obtained from the reaction were found to be unreacted 32 and the naphthoquinone derivative 70. 27 Xylene reflux 32 70 The structure of 70 was established by its mass, 111 PMR and 130 MIR spectra. The mass spectrum showed a molecular ion seek at 3/9 510. The 111 101R spectrum of 70 consisted of a singlet at 5 6.13 for the ”outer" bridgehead hydrogens, a two-proton singlet at 6 6.77 for the "inner” bridgehead hydrogens, a two-proton singlet at 5 7.41 for the quinoid ring hydrogens and three sets of multiplets in the aromatic region for the total of 16 hydrogens. The 130 MAR spectra of 70, which showed two peaks at 5 48.69 and 50.27 for the sp3 bridgehead carbon atoms, as required by sy-etry, eight peaks for the sp2 carbon atoms and a single peak at 5 188.55 for the carbonyl carbon atoms, also supported this structure. Several factors may be responsible for the low yield ((30-358) of 70 and the absence of the bisadduct. The low yield may result because some of the p—benzoquinone is consumed by the dehydrogenation. The absence of the bisadduct can be accounted for by assuming that the rate of the second cycloaddition reaction is slower than the rate of the dehydrogenation-dehydrochlorinat ion of the monoadduct. The yield of 70 28 increased to >803 when up to ten equivalents of p-benzoquinone were used in this reaction. A follow—up reaction in which a 1:1 mixture of 32 and 70 in xylenes was heated at reflux for 24 hours did not give the expected bisadduct 71 . 32 70 11 When a mixture of 32 and 70 in xylenes was heated at 210-22000 in a sealed tube, an inseparable mixture of products was obtained from which the desired 71 could not be isolated. 7. Synthesis of 1,4; 1’,4’-di-o—benzeno—1,1,’4,4’-tetrahydro— 2 , 2 ’-binaphthyl 56 The complexity of the reaction of 32 with naphthoquinone 70 and the formation of hydrogen chloride in the reactions of 32 at high temperatures, which might be responsible for the unprecedented outcomes of some of these reactions, called for the synthesis of the parent hydrocarbon, the butadiene derivative 56. The dechlorination of 32 was achieved by treating a solution of this compound in TRF with 2.2 equivalents of n—butyllithia for four hours at -78°C, followed by 30 minutes at reflux. The solution was then cooled and quenched with methanol, to give 633 of the desired 56. The structure of 56 was confirmed by mass, 111 MR and 13C MIR spectra. The mass spectra showed 29 a molecular ion peak at m/e 406. The 13 NMR spectrum showed a singlet at 5.12 for the "inner" bridgehead protons, and a peak at 7.10 for the vinyl protons, as well as appropriate peaks for the aromatic protons. The 13C NMR spectrum, as required by the symmetry, showed only two peaks for the sp3 hybridized bridgehead carbon atoms, at 51.31 and 52.60, and a total of seven peaks for the sp2 carbon atoms. Since treatment of 32 with 1.1 equivalent of n-butyllithium under the same conditions, followed by quenching with methanol, resulted in the partial dechlorination of 32 and recovery of some of the starting material, it seems likely that the intermediate in this reaction is the dilithiated 1,3-butadiene derivative 72, which upon quenching with a proton source gives 56. The existence of 1,4-dilithiated-l,3-butadiene species similar to 56 is experimentally well established.‘0 (Z)-1,4- dilithio-l,3-butadiene is predicted to be a very stable compound.‘o 32 ”’BULi (2 «4 > 30 8. Reaction of 56 with trans:l,2-dichloroethylene. Beating a suspension of 56 in trans-1,2-dichlorethylene at 195- 200°C in a sealed tube for 24 hours gave the expected cycloadduct 73 in 91% yield. The structure of 73 was confirmed by its 1H mm and 13C MIR spectra. The 18 NMR spectrum of 73 showed four sets of multiplets, each for one proton on the central ring, doublets at 6 4.51 and 4.60, each for one proton for the ”inner" bridgeheads and two singlets at 6 5.31 and 5.35 for the "outer" bridgeheads, and two sets of multiplets for the aromatic protons. The 13C NMR spectrum was also consistent with this structure, with eight peaks corresponding to the 8 sp3 hybridized carbon atoms and 20 peaks corresponding to the sp2 hybridized carbon atoms. 9. Synthesis of [1.1.1‘ .1.1] pentiptycene 2. Dehydrochlorination of the cycloadduct 73, with excess sodia methoxide in refluxing methanol, afforded the a,c— fused pentiptycene 2 in 873 yield. The lBINMR and 13C NMR spectra of 2 have been previously described (p.27). 10. Reaction of 56 with cyclohexene. Cycloadduct 74 was prepared in 913 yield by heating a suspension of 56 in cyclohexene at 195-20000 in a sealed tube for 36 hours. Compound 74 was characterized by its mass, 1B NMR and 13C NMR spectra. The mass spectrum had a peak at m/g 488 corresponding to the molecular ion. The 111 MIR spectrum showed a broad singlet, a broad doublet, and a broad singlet at 6 0.47, 1,32 and 1.53 for 2,2 and 6 protons respectively, corresponding to the aliphatic protons. It also showed a 32 broad doublet at 6 1.88 for the allylic protons, a doublet at 6 4.18 for the "inner” bridgehead and a sharp singlet at 6 5.35 for the "outer" bridgehead protons. The 16 aromatic protons appeared at 6 6.93—7.38 as a multiplet. The 130 MAR spectra of 74 showed six peaks for the sp3 hybridized carbon atoms, as expected by sy-etry, and a total of 10 peaks for the sp2 carbon atoms. Attempted dehydrogenation of 74 with 103 palladia on charcoal in refluxing mesitylene for four days gave a complex mixture of products, which were not separated. 11. Reaction of 56 with 1,4-epoxynaphthalene 38 Beating a solution of 56 and 1,4-epoxynaphtha1ene in xylenes at reflux for eight hours gave the expected cycloadduct 75 in 953 yield. X + I rgg‘: 56 75 The mass spectra of 75 showed a molecular ion peak at m/e 550. The 111 “IR spectra showed a doublet of doublets at 6 0.97, a broad doublet at 2.33, and a doublet at 6 4.40 corresponding to the a,b and c protons respectively (Figure 4). 33 Figure 4. Stereo drawing of the central ring of the cycloadduct 75. The bridgehead protons appeared at 6 5.28 and 5.30 as sharp singlets, and the 20 aromatic protons at 6 6.95-7.31 as a multiplet. The stereo-chemistry of 75 was not established unequivocally. However, the dramatic upfield shift of the a protons and the small coupling with the c protons (Jae use) suggests an exo addition in which the a protons are sandwiched between the aromatic rings. The 13C NMR spectrum of 75 showed five peaks for the sp3 carbon atoms (plane of symetry) and a total of 14 peaks for the spa carbon atoms. Cycloadducts such as 75 can readily be dehydrated with acid. Thus 75 was dehydrated by addition of concentrated sulfuric acid to a solution of 75 in acetic anhydride and stirring for 10 minutes to give 76 in 733 yield. 34 The structure of 76 was established based on its 111 INR and 13C MIR spectra. The 111 MAR showed a broad singlet at 6 3.16 for the methyne protons on the non-aromatic ring, a broad singlet at 6 5.14 for the ”inner" bridgehead protons, a sharp singlet at 6 5.46 for the ”outer" bridgehead protons and four sets of multiplets at 6 6.85-7.48 corre- sponding to the 22 aromatic protons. The 13C MR spectra showed three peaks at 6 46.30, 46.68 and 48.88 for the sp3 carbon atoms (plane of sy-etry) and a total of 13 peaks for the sp2 carbon atoms. In the acid catalyzed dehydration of 54, a 1,3 hydrogen shift was observed. 55 The orbital sy-etry rules require that such 1,3 shifts be antarafacial. This process introduces a small amount of additional strain which can be compensated for by the energy gained through conjugation. The sy-etry of 76, deduced from its 111 [HR and 130 MAR spectra, indicate the lack of any rearrangement. A 1,3 hydrogen migration in 76 would imply a trans fusion of one of the 9,10-anthradiy1 moieties, thus imposing considerable strain on the molecule. Therefore, in contrast with 54, hydrogen migration in 76 is a very unfavorable process. 12. Dehydrogenation of 76 Dehydrogenation of 76 in the presence of BBQ in refluxing benzene gave 77 in 92% yield. Solutions of 77 were greenish yellow, and under UV light showed a very strong fluorescence, consistent with the presence of an anthracene moiety. The structure of 77 was confirmed by its 111 101R spectra, which showed two singlets at 6 6.25 and 6.36 for the ”inner" and "outer” bridgehead protons respectively. A singlet at 6 8.84 corresponded to the protons on the middle anthracene ring. The rest of the aromatic protons appeared at 6 6.94-8.03 as five sets of multiplets. The 13C MIR spectra, which showed two peaks at 6 50.64 and 51.57 for the spa bridgehead carbon atoms and a total of 13 peaks for the aromatic carbon atas (Czh sy-etry), also supported this structure. 13. Synthesis of the Beptiptycene 4 Refluxing a solution of 77, excess benzenediazoniacarboxylate hydrochloride and propylene oxide in 1,2-dichloroethane for 12 hours afforded the known heptiptycene 4 in 26% yield. 36 Considering the yield and the number of steps involved, this method is obviously not comparable with the previously known one step synthesis of 4 via the trimerization of the cycloalkyne 31 in 20% yield (p. 4). This synthesis of 4, however, demonstrates the potential utility of this method in the construction of other iptycenes bearing a,c-fused 9,10- anthradiyl moieties. 14. Synthesis of 5,14; 8,13—di-o—benzeno-6’,7’-dichloro-5,8,13,14— tetrahydro—6,7-naphthopentaphene 81. It was mentioned earlier that the addition of iptycynes to anthracene is not a preferred method for the construction of the other iptycenes. The method, nevertheless, can be regarded as an alternative. Taking this into consideration, compound 81, a dichloro derivative of 77 and a potential iptycyne precursor, was synthesized using the same sequence of reactions as for 77 itself. Thus, 6,7-dichloro-1,4- epoxynaphthalene 78 was added to 56 to give 79 in quantitative yield. Dehydration of 79 in acetic anhydride by concentrated sulfuric acid gave 80 in vex yield. Dehydrogenation by 000 in refluxing benzene afforded 81 in 95s yield. 80 81 The structures of 79, 80 and 81 were confirmed by their mass, 111 10411 and 11"C W spectra. Tables 2 and 3 lists the spectral data for these three compounds . 15. Reaction of 56 with 70 A solution of 56 and 70 in xylenes at reflux for 12 hours gave the cycloadduct 82 in 94* yield. Table 2. 38 1H NMR Chemical Shifts (ppm) of Compounds 79, 80 and 81. Compound Chemical Shift (PPB) 0.97 (dd,ZH), 2.31 (broad d, 28), 4.40 (d,2H), 5.29 (3,2H), 5.49 (3,28), 6.90 (3,28), 6.98 (m, 4H), 7.09 (m,4H), 7.21 (m,4H), 7.32 (m,4H). 3.21 (3,28), 5.20 (3,2H), 5.47 (3,2H), 6.89 (m,4H), 7.15 (m,8H), 7.36 (3,28), 7.45 (m,4H), 8.27 (3,2H). 6.29 (3,2R), 6.40 (3,28) 6.97 (m,8H), 7.39 (3,28), 7.51 (m,4H), 7.53 (m,4H), 9.26 (3,2H) 39 Table 3. 13C NMR Chemical Shifts (ppm) of Compounds 79, 80 and 81. Compound Chemical Shift (ppm) 9 ' 45.61, 43.55, 49.29, 83.06 I i 9 . @C' 1 123.15, 124.11, 124.46, 126.14 6 {a c. 126.19, 126.57, 126.95, 129.00, Q 131.13, 141.04, 142.39, 143.95, 145.49 46.61 (overlap), 49.04, 120.53, 123.36, 124.11, 124.70, 126.07, 126.12, 126.44, 126.90, 127.03, 130.40, 131.35, 140.91, 141.41, 142.62, 142.80, 144.33, 146.03. 50.72, 51.64, 120.00, 124.06, 124.32 125.03, 125.72, 127.05, 129.20, 131.66, 140.63, 141.49, 145.95, 146.33. 40 The structure of 82 was confirmed by its mass, 111 MR and 130 MIR spectra. The mass spectra showed a molecular ion peak at m/g 918. The 111 mm spectra showed a four proton multiplet at 6 1.85 for the protons on the cyclohexene ring, two singlets, each for two protons, at 6 4.57 and 5.31 for the bridgehead protons of the 9,10-anthradiy1 moieties fused to the non-aromatic site, two singlets, each for two protons, at 6 6.04 and 6.63 for the bridgehead protons of the 9,10eanthradiy1 moieties fused to the aromatic site, as required by sy-etry, and six sets of multiplets for the 32 aromatic protons at 6 6.98-7.67. The 13'0 TMR spectra of 82, in which six peaks appeared for the six pairs of the sp3 carbon atoms and a peak at 6 199.25 for the pair of carbonyl carbon atoms, supported this structure. This compound was found to oxidize gradually when exposed to air. 16. Oxidation of 82 to the anthraquinone derivative '. There are several methods for oxidizing a saturated 1,4-cyc1ic dione to the corresponding quinone.“2 Among these, halogenation- dehydrogenation by NBS and N08 is frequently used. Heating 3 solution of 82 and NBS in carbon tetrachloride at reflux afforded in quantitative yield. 41 The melting point of this compound is )500°C. It was characterized by its l11 ram and 13C MIR spectra. Both spectra showed very simple patterns due to the high sy-etry of the compound (Dad). The 11! BER spectrum showed two four-proton singlets at 6 6.08 and 7.10 for the "outer" and ”inner” bridgehead protons respectively. The 32 aromatic protons appeared as three sets of triplets. The 13C MIR spectra showed two peaks at 6 50.01 and 50.70 for the spa bridgehead carbon atems, 9 peaks for the 3p2 carbon atoms, and a single peak at 6 188.63 for the carbonyl carbon atoms . 17 . Reduction of I. Reduction of anthraquinones to the corresponding anthracenes has been carried out under various conditions and by a variety of reducing agents. These reactions are sensitive to the nature of the substituents and substitution pattern and often give a mixture of products. We investigated the reduction of using several methods such as catalytic hydrogenation, lithia trialkoxyalaina hydride, sodium borohydride/ trifluoroacetic acid, zinc sodium hydroxide, lithia aluminum hydride/alaina chloride, zinc acetic acid/pyridine, to name a few.“ Except for the last two methods, the others lead to a mixture of products which, during the work up and purification, oxidized mostly to the starting material .. Zinc/acetic acid/pyridine always lead to a mixture of 58 and its dihydro derivative 84. 42 THF The lithia alumina hydride/alainum chloride method gave predominantly 84 in 91% yield along with a trace of 58. The two compounds were separated by addition of an excess TONE to a solution of 84 and 58 in methylene chloride, followed by chromatography of the residue after evaporation of the solvent. The structure of 84 was determined by its 111 MIR and 130 101R spectra. The 111 MIR spectra showed a four proton singlet at 6 4.24 for the benzylic protons on the middle ring, two four proton singlets at 6 5.90 and 5.94 for the "inner" and ”outer" bridgehead protons respectively, and three sets of doublets of doublets for the 32 aromatic protons, as required by symmetry (Dad). The 13C 191R spectra showed three peaks for the sp3 hybridized carbon atoms and 8 peaks for the sp2 aromatic carbon atoms. The melting point of 84 is above 500°C. 18. Dehydrogenat ion of 84. Catalytic dehydrogenation of 84 by palladia/charcoal in refluxing mesitylene failed to give the expected product 58. Reaction of 84 with DDG in refluxing benzene,” however, resulted in its conversion to 58. This transformation could be verified by the 111 [MR spectra of the 43 crude product, in which the signals for the benzylic protons of 84, at 4.24 disappeared. Compound 58 complexes with either excess DDO present in the solution or with its reduced form DDHQ. Separation is achieved quantitatively by absorbing the reaction mixture on silica gel and heating at 250-300°C under vacuum for 10 minutes, followed by chromatography. The melting point of 58 is >500°C. It was characterized by its mass and 111 MR spectra. The mass spectra of 58 showed a molecular ion peak at g/g 882. The 111 BUR spectra showed two four proton singlets at 6 6.31 and 6.42 for the "inner" and "outer" bridgehead protons, three sets of multiplets for 32 protons on the benzene rings of the 9,10- anthradiyl moieties and a singlet at 6 9.28 for the two protons of the anthracene moiety. The utility of the 9,10-anthradiy1 fused anthracenes as easy entries into higher iptycenes need not be emphasized. The synthesis of 58 and 77 undoubtedly constitutes an important step toward the construction of the other a,c-fused members of this class of compounds. For example, the Diels-Alder reactions of 58 and 77, with suitable 44 dienophiles such as trichloroethylene and 1,4-epoxyanthracene 41, could provide entries into iptycenes 24, 17, 23, and 10 (Table l) by elaboration of the resulting cycloadducts, as illustrated in Figures 5 and 6. CIHC =(2Cl2 - HCI - HCI 4S FiSUPGES. Schematic representation of the possible syntheses of iptycenes l7 and 24 from the reaction of anthracene derivatives 77 and 58 with 1,2-dichloroethylene. 46 1figure 6. Schematic representation of the possible syntheses of iptycenes 10 and 23 from the reaction of anthracene derivative 17 and 58 with 1,4-epoxyanthracene. EXPERIMENTAL 1. General Procedure MIR spectra were recorded on a Brucker PM 250 MHz spectrometer using 0001: as solvent (except 58, for which 002012 was used) and (Oils )4Si as the internal reference. IR spectra were determined on a Perkin Elmer 167 spectrometer. Mass spectra were measured at ‘70 all using a Finnigan 4000 spectrometer with the INCOS data systu, operated by Mr. Ernest Oliver or Mr. Richard Olson. High resolution mass spectra were obtained with a JEOL llelO HF spectrometer at Michigan State University Mass Spectrometry Facility. Melting points were determined with an electrothermal melting point apparatus (Fisher Scientific), or with a Thomas Hoover melting point apparatus and are uncorrected. Microanalyses were performed by Spang Microanalytical Laboratory, Eagle Harbor, Michigan . 2 . 3-Chloro—l , 4 , l ’4 ’-tetrahydro-l , 4; l ’ , 4 ’-di-o-benzeno-2 , 2 ’- jbinaphthyl 32 To a suspension of 9.55 g (40 .01) of ll-chloro-9,10-dihydro- 9, lO—ethenoanthracene in 100 ml. of anhydrous hexanes and 25 ml. of anhydrous THF under argon at -78°C was added dropwise 18 mL (45 mmol) of 2.5M n-butyllithium in hexanes. The reaction mixture was brought to room temperature, vigorously stirred (mechanical stirrer) for two hours, refluxed for 30 minutes, and then allowed to cool to room temperature. Water was slowly added (50 ml.) followed by 200 ml. of methylene chloride. The aqueous layer was discarded. The organic layer was washed with. saturated sodium chloride solution and dried over anhydrous magnesia sulfate. The solvent was removed. Chromatography of the residue on a 47 48 silica gel column using a 1:5 mixture of methylene chloride/hexanes as eluent gave 6.5 g (73x) of the desired product as a white solid; m.p. 268°C (Lit. 268°C) .10 3. 6-Chloro-5,8,13,l4-tetrahydro-5,14;8,l3-di~o—benzeno- pentaphene 65 A suspension of 1.77 g (4.0 mmol) of 31 in 30 mL of trans—1,2- dichloroethylene in a sealed tube was heated at 190-195°C for 36 hours. After cooling to 0°C the tube was opened and the excess solvent was removed. The residue was added to 125 ml. solution of 4:1 TIE/methanol containing 0.4 g (10 -01) of sodium hydroxide. The mixture was heated at reflux for 48 hours. The solvent was removed and the residue was taken up in methylene chloride. The methylene chloride solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the residue on a silica gel colum using a 1:4 mixture of methylene chloride/hexane as eluent gave 1.27 g (68%) of the desired product as a white solid; m.p. 358-359"C, 1!! mm (0001:) 6 5.28 (s,lll), 5.83 (3,18), 5.91 (3,18), 5.96 (s,lll), 6.94 (m,8l-l), 7.03 (3,111), 7.29 (13,211), 7.36 (m,28), 7.42 (m,4H); 130 MR (C0013) 6 50.02, 50.63, 50.83, 53.94, 121.11, 123.96, 124.08, 124.45, 125.84, 138.13, 139.31, 141.54, 467(6), 466(43), 464(67), 429(49), 138(78), 111(100), 82(96), 77(70). Anal. Calcd. for 03482101: C, 87.82; 11, 4.56. Found: C, 87.91; ll, ”mac—«nu 49 4. 1,4,1’,4’-Tetrahydro-l,4;l’,4’-di—o-benzeno-2:2’-binaphthyl 56 To a suspension of 8.82 g (20 .01) of 32 in 250 mL of anhydrous THF under argon at ~78°C was added dropwise 18 ml. (45 mol) of 2.5 M n- butyllithium in hexanes. The reaction mixture was brought to room temperature and stirred for four hours, heated at reflux for 30 minutes and then cooled to 0°C. The dark brown solution was slowly and carefully quenched with 5 mL of methanol. The solvent was removed and the residue was taken up in methylene chloride. The methylene chloride solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the solid material on a silica gel column using 1:4 methylene chloride/hexanes as eluent gave 5.1 g (63%) of 56 as a white solid, m.p. 323—3240C; 1H MIR (00013) 6 5.13 (d,3ll), 5.16 (s,lll), 6.88 (m,88), 7.10 (dd,2li), 7.21 (m,88); l3C MIR (CDCla) 6 51.31, 52.60, 123.12, 123.78, 124.90, 125.10, 131.04, 145.80; mass spectrum m/g (relative intensity), 407(6), 406(24), 228(34). 203(26), 202(1(), 191(12), 178(100). Anal; Calcd. for Cazflézz C, 94.54; H, 5.45. Found: C, 94.41; 8, 5.48. 5. 6,7-Dichloro-5,6,7,8,13,14—hexahydro-5,14;8,13-di-o— benzenopentaphene 73 A suspension of 1.63 g (4 umol) of 56 in 30 ml. of trans-1,2- dichloroethylene in a sealed tube was heated at 190-19500 for 24 hours. After cooling to 0°C the tube was opened and excess solvent was evaporated. Chromatography of the remaining residue on a silica gel column using 5:1 hexanes/methylene chloride as eluent gave 1.84 g (912) of the desired product as an off—white solid; m.p. 267-268°C, 111 MIR (011013) 6 2.23 (d,IH), 2.67 (dd,lll), 2.73 (d,ll-l), 4.41 (t,lll), 4.51 SO (d,lfl), 4.60 (d,IH), 5.31 (s,18), 5.35 (8,1H), 7.03 (m,88), 7.29 (m, 811); 130 MIR (00013) 6 45.62, 47.59, 48.56, 48.86, 49.11, 49.32, 66.63, 69.89, 122.80, 123.14, 123.57, 124.27, 124.50, 126.10, 125.19, 126.64, 126.86, 127.36, 128.15, 130.34, 131.16, 139.25, 141.54, 142.03, 142.34, 142.96, 143.16, 144.68; mass spectrum m/e (relative intensity), 502(5), 467(4), 431(19), 289(8), 253(13), 178(100). Anal. Calcd. for C34Hé4C12: C, 81.11; 8, 4.80. Found: C, 80.94; H, 4.77. 6. 5,8,13,14-Tetrahydro-5,l4;8,13—di-o-benzenopentaphene 2 To a solution of 0.40 g (excess) sodium hydroxide in 250 mL of 4:1 tetrahydrofuran/methanol was added 1.52 g (3 mmol) of 73. The solution was heated at reflux for 36 hours. The solvent was then removed and the residue was taken up in methylene chloride. The methylene chloride solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. After evaporation of the solvent, chromatography of the residue on a silica gel column using a 1:3 methylene chloride/hexanes as eluent gave 1.15 g (87%) of the product, m.p. 315-316PC, 18 NMR (CDCls) 6 5.31 (s,28), 5.94 (s,28), 6.94 (m, 108), 7.30 (m,4H), 7.42 (m,4H); 130 MIR (CDCla) 6 50.51, 54.59, 120.43, 124.05, 125.71, 139.62, 142.57, 145.43, 146.01; mass spectrum g/g (relative intensity), 431(22), 430(100), 252(49), 178(20). Anal. Calcd. for 0341122: C, 94.85; H, 5.15. Found: C, 94.89; H, 5.12. 7. 5,6,7,8,13,14,1’,2’,3’,4’-Decahydro-5,14;8,13-di-o-benzeno- 6,7-benzopentaphene 74 A suspension of 1.63 g (4.0 .01) of 56 in 30 mL of cyclohexene in a sealed tube was heated at 195-20000 for 36 hours. After cooling to 0°C the tube was opened and the excess cyclohexene was removed. Sl Chromatography of the residue on a silica gel column using a mixture of 4:1 hexanes/methylene chloride as eluent afforded 1.78 g (91%) of 74 as a white solid, m.p. 295—296°C, 111 MIR (CDCla) 6 0.49 (broad 3,211), 1.32 (broad d,2H), 1.53 (broad 3,611), 1.88 (broad d,2H), 4.18 (d,2H), 5.35 (3,211). 6.93-7.38 (m,1611); 13C MIR (CD013) 6 23.75, 28.12, 40.41, 47.02, 49.05, 49.58, 123.33, 123.96, 124.83, 125.75, 126.58, 132.30, 141.25, 310(8), 178(100). Anal. Calcd. for Casi-132: C, 93.40; H, 6.60. Found: C, 93.49; H, 6.69. 8- (.1.3....3!I....,Z...1....2::TetElma-:1_.’.-.._&...’__;..2.....12791:9:P§9§999:§.fi: naphthotetraphene—l,47dione 70 A solution of 4.41 g (10 mmol) of 32 and 10.80 g (excess of p- benzoquinone in 250 mL of xylenes was heated at reflux for 36 hours. The solvent, along with most of the excess p-benzoquinone, was removed by vacuum distillation. Chromatography of the remaining dark brown solid on a silica gel column using a mixture of 3:2 methylene chloride/hexanes as eluent afforded 4.4 g (868) of 70 as a bright yellow solid, m.p. 393°C, 111 W (CDCla) 6 6.13 (3,211), 6.77 (3,211), 7.01 (m,81l), 7.41 (3,211), 7.48 (dd,8H); 130 [MB (00013) 6 48.69, 50.27, 118.53, 123.69, 125.11, 126.22, 139.00, 143.84, 144.32, 146.06, 188.55; mass spectrum m/g (relative intensity), 512(8), 511(44), 410(100), 427(23), 178(28). Anal. Calcd. for Casflzzozz C, 89.39; H, 4.34. n.”.~...m ............ Found: C, 89.23; H, 4.24. 52 9. 1,1,,1”,l”’,1T".H,4,§’;4H,4"’,4H’"DecahYdI'O- l ’,4’; 1 ”,4”; lgffigl’", 1 ””,4””-tetra-o-benzen9jj 1,2;3,4;5,6;7,8:tetranaphthoanthra-9,10-dione 82 A solution of 2.05 g (5 .01) of 56 and 2.51 g (5 .01) of 70 in 250 ml. of xylenes was heated at reflux for 12 hours. The solvent was removed. Chromatography of the remaining solid using 2:1 methylene chloride/hexanes as eluent gave 4.3 g (942) of 82 as a white solid, m.p. 380- 382°C, 18 M18 (00013) 6 1.85 (m,48), 4.57 (3,28), 5.31 (3,28), 6.04 (3,28), 6.63 (3,28), 6.98 (m,88), 7.10 (m,48), 7.27 (m,88), 7.44 (m,68), 7.56-7.67 (m,68); 130 M18, 6 45.33, 47.88, 48.63, 49.86, 50.63, 52.90, 123.12, 123.94, 124.13, 124.22, 124.33, 124.67, 125.36, 126.21, 126.36, 126.66, 127.13, 127.24, 128.75, 128.94, 130.72, 140.20, 142.07, 143.58, 144.04, 144.64, 144.95, 145.19, 199.25. Mass spectrum m/g (relative intensity), 918(0.7), 917(2), 916(2), 738(19), 485(22), 427(14), 426(12), 178(100). 49.9.1.3. Calcd. for 07084402: 0, 91.67; 11, 4.83. Found: 0, 91.63; 8, 4.82. lo. 1,1,,III’lII’,1I”’j4,4’j4”14””4”’l-DecahYdro- 1’,4I;1”,4’I3ll’ID4I’I’lllll,4llll_tetra-o_benzeno_ 1,2;3,4;5,6;7,8-tetranaphthoanthra-9,10-dione 83 A solution of 1.84 g (2 .01) of 82 and 2.5 g (excess) of N- brcmosuccinimide in 300 ml. of carbon tetrachloride was heated at reflux for 12 hours. The solvent was removed. Chromatography of the resulting solid on a silica gel column using 1:1 methylene chloride/hexanes as eluent gave 1.78 g (97%) of 83 as a pale yellow solid; m.p. >450°0; 18 mm (00013) 6 6.08 (3,48), 7.00 (t,168), 7.10 (3,48), 7.45 (t,88), 7.56 (t,88); 130 [NE (00013) 6 50.01, 50.70, 124.14, 125.18, 126.27, 126.37, 127.85, 143.90, 144.48, 144.93, 145.09, 188.63; the mass spectrum could 53 not be obtained. Anal. Calcd. for 07084002: 0, 92.08; 8, 4.41. Found: C, 91.96; 8, 4.39. 1 1 ° 5,58,6,7,78,8 .2 13’14’1’v4 1713868113151! 0'5 :14’8! 13—d1_°” ggnzeno-l’.4’.-oxo-6.7 naphthopent92b99§MZ§ A solution of 1.02 g (2.5-01) of 56 and 0.36 g (2.5 mmol) of 1,4-epoxynaphthalene in 125 mL of xylenes was heated at reflux for eight hours, after which the solvent was removed. Chromatography of the residue on a silica gel column using 2:1 hexanes/methylene chloride afforded 1.3 g (95%) of 75 as a white solid; m.p. 369-370°0, 18 1018 (00013) 6 0.97 (dd,211), 2.33 (broad d,28), 4.40 (d,28), 5.28 (3,28), 5.30 (3,28), 6.95 (m,48), 7.08 (m,68), 7.17 (m,68), 7.31 (m,48); 130 M18 (00013) 6 46.10, 48.63, 49.54, 83.43, 119.14, 123.17, 124.01, 124.10, 125.80, 126.48, 126.87, 127.08, 131.05, 141.27, 142.29, 142.54, 144.23, 145.98; mass spectrum m/e (relative intensity), 550(5), 445(1), 431(2), 253(5), 178(100), 118(46). Anal. Calcd. for 04211300: 0, 91.60; 11, u..u~.—.n...-¢m 5.49. Found: 0, 91.31; 8, 5.63. 12. 5,14;8,13-0i-o-benzeno-5,53,7a,8,13,l4—hexahydro-6,7- naphthopentaphene 76 To a solution of 0.56 g (1.0 mol) of 75 in 15 mL of acetic anhydride was added slowly 2 m1. of concentrated sulfuric acid. The solution was stirred for 3-5 minutes and then poured onto ice water. The organic material was extracted in ether. The ether solution was washed three times with 103 sodium hydroxide solution, water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the residue on a silica gel column using 4:1 hexanes/methylene chloride as eluent gave 0.39 g 54 (732) of 76 as a white solid, m.p. >400°C (dec.), 18 NMR (00013) 6 3.15 (3,28), 5.14 (3,28), 5.46 (3,28), 6.85 (m,48), 7.12 (m,68), 7.39 (m,88), 7.48 (13,48); 13'0 NMR (00013) 6 46.30, 46.68, 48.88, 122.63, 123.02, 124.23, 125.71, 125.99, 125.58, 127.92, 131.08, 132.00, 138.97, 140.85, 142.44, 144.47; mass spectrum m/e (relative intensity) 533(8), 532(29), 355(24), 354(100), 353(50), 179(8), 178(15), 86(24), 84(44). High resolution mass spectrum calcd. for 0‘2828 = 532.6914; Found: 532.6882. 13. 5,14;8,lB-Di-o-benzenoj5,8,13,14—tetrahydro-6,7- naphthopentaphene 77 A solution of 0.54 g (1 mmol) of 76 and 0.23 g (1 mmol) of 2,3- dichloro-5,6-dicyano-l,4-benzenoquinone in 50 mL of benzene was heated at reflux under argon for 12 hours. Evaporation of the solvent and chromatography of the resulting solid on a silica gel column using 3:1 hexanes/methylene chloride as eluent gave 0.50 g (92%) of 77 as a yellow solid, m.p. 470-72°0 (dec.), 18 NMR (00013) 6 6.25 (3,28), 6.36 (3,28), 6.94 (m,88), 7.39 (dd,28), 7.48 (m,88), 8.03 (dd,28), 8.84 (3,28); 130 1MB (00013) 6 50.64, 51.57, 121.70, 123.95, 124.12, 126.58, 127.69, 128.81, 129.20, 131.69, 146.26, 146.70; mass spectrum gun/e (relative intensity) 531(30), 530(100), 352(36), 256(7). High resolution mass spectrum calcd. for 0428.26 = 530.6755; Found: 530.6735. 14. 5,53,6,7,7a,8,13,14,1’,4’-0ecahydro-5,14;8,13-di-o—benzeno- 6 ’, 7 ’-dichloro-1 ’ , 4 ’-oxo—6, 7-naphthopentaphene 79 A solution of 1.02 g (2.5 mmol) of 56 and 0.54 g (2.5 mmol) of 6,7-dich10ro-1,4-epoxynaphthalene in 125 mL xylenes was heated at reflux for eight hours, after which the solvent was removed. Chromatography of the residue on a silica gel column using 2:1 hexanes/methylene chloride 55 as the eluent gave 1.42 g (91%) of 79 as a white solid, m.p. 360-36100, 18 ma (00013) 6 0.97 (dd,28), 2.31 (broad d,28), 4.40 (d,28), 5.29 (3,28), 5.49 (3,211), 6.90 (3,28), 6.98 (13,411), 7.089 (m,4H), 7.21 (m,48), 7.32 (m,48); 130 M18 (00013) 6 45.61, 48.55, 49.29, 83.06, 123.15, 124.11, 124.46, 126.14, 126.19, 126.57, 126.95, 129.00, 131.13, 141.04, 142.39, 143.95, 145.49; mass spectrum m/e (relative intensity), 620(0.3), 618(0.9), 431(3), 186(10), 178(100), 86(16), 84(26). ”Anal”. Calcd. for 0428230120: 0, 81.42; 8.4.55. Found: 0, 81.44; 8, 4.53. 15. 5,14;8,13-Di-o-benzeno-5,53,7a,8,13,14-hexahydro—6’,7’- ssIN-m To a solution of 0.62 g (1.0 .01) of 79 in 15 ml. of acetic anhydride was slowly added 2 mL of concentrated sulfuric acid. The reaction mixture was stirred for 3-5 minutes and then poured onto ice. The organic compounds were extracted with ether. The ether solution was washed with water, 10% sodium hydroxide solution, water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the residue on a silica gel column using 3:1 hexanes/methylene chloride as eluent gave 0.46 g (763) of so as a faint yellow solid, m.p. 340-34200; 18 M18 spectrum (00013) 6 3.21 (8,211), 5.20 (8,28), 5.47 (8,211), 6.89 (m,48), 7.15 (m,88), 7.36 (3,28), 7.45 (m,48), 8.27 (3,28); 130 M48 spectrum (00013) 6 46.6 (overlap), 49.0, 120.5, 123.3, 124.1, 124.7, 126.0, 126.1, 126.4, 126.9, 127.0, 130.4, 131.3, 140.9, 141.4, 142.6, 142.8, 144.3, 146.0; mass spectrum m/e (relative intensity) 603(2), 602(6), 601(6), 600(18), 598(15), 422(20), 179(27), 178(100). High resolution mass spectrum calcd. for 0‘2830012: 601.5817; Found: 601.5695. 56 16- §.1&n§.13:91:9:§99§§99:§fn?ftéishlqr9zfin8.13.14ttetrahydro- 6,7-naphthopentaphene 81 A solution of 0.60 g (1 mmol) of 80 and 0.23 g (1 mmol) of 2,3- dichloro-5,6—dicyano-1,4-benzoquinone in 75 mL of benzene was heated at reflux under argon for 12 hours. Evaporation of the solvent and chromatography of the resulting solid on a silica gel column using 3:1 hexanes/methylene chloride as eluent gave .57 g (95%) of 81 as a bluish yellow solid, m.p. 380-382°0; 111 1MB (00013) 6 6.29 (3,211), 6.40 (3,28), 6.97 (m,88), 7.39 (3,28), 7.51 (m,48), 7.53 (m,48), 9.26 (3,28); 130 NH (00013) 6 50.72, 51.64, 120.00, 124.06, 124.32, 125.03, 125.72, 127.05, 129.20, 131.66, 140.63, 141.49, 145.95, 146.33; mass spectrum Ill/g (relative intensity) 602(3), 601(10), 600(40), 598(48), 422(16), 420(26), 264(18), 262(14), 178(46), 44(100). Anal Calcd. for 042824012: 0, 84.14; 8, 4.03. Found: 0, 84.22; 8, 4.11. 17. 1,1’,3,3’,4,4’-8exahydro-1,4;1’,4’-di-o—benzeno-3:3’- binaphthyl-2,2’-dione 60 To a solution of 3.6 g (22 mmol) of 1,1,1,3,3,3-hexamethy1— disilazine in 20 ml. of anhydrous ether was added dropwise 9.0 ml. (22 mmol) of 2.5 M n-butyllithium in hexanes. The exothermic reaction was accompanied by formation of a crystalline product. After the addition was complete, the solvents were removed by flushing argon gas through the flask, and were replaced by 50 mL of dry T8F. The solution was cooled to -78°C and a solution of 4.4 g (20 mmol) of 1,3,4—trihydro-1,4- o—benzeno-naphthalene—2-one in 40 mL of anhydrous T8? was added dropwise. The reaction mixture was stirred for two hours at -78°C and then a solution of 3.3 g (20 mmol) of ferric chloride in 25 ml. of dry N,N-dimethy1formamide was added. The reaction mixture was warmed to 57 room temperature and stirred over night. The solution was diluted with 150 ml. of methylene chloride, washed with water, 10* hydrochloric acid solution, water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the residue on a silica gel column using 2:1 hexanes/methylene chloride provided 2.8 g (593) of 60 a white solid, m.p. 321—322°0. 18 1848 (00013) 6 1.73 (s,28), 4.77 (3,28), 5.02 (3,28), 7.12 (m,88), 7.23 (m,28), 7.31 (m,28), 7.46 (m,28); 130 M111 (00013) 6 47.25, 47.55, 63.70, 125.01, 125.60, 127.18, 127.87, 205.28;. 4.9.31.1 Calcd. for 03282202: 0, 87.46; 11, 5.05. Found: C, 87.50; 8, 5.11. 18. 9, 10-Dihydroanthracene Derivative 84 To a suspension of 0.38 g (10 .01) of LiAlHa in 100 ml. of anhydrous T8F under argon was added 0.92 g (1 .01) of I. The reaction mixture was heated at reflux for four hours, cooled to 0°C and 0.66 g (5 .01) of aluminum chloride was added in small portions. The solution was then heated at reflux for two hours and the excess LiAlflo was hydrolyzed with 3 ml. of water. The organic layer was decanted, the solvent was removed and the remaining residue was dissolved in methylene chloride. The methylene chloride solution was washed with water and sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent volume was reduced to 10ml., a small amount of tetracyano- ethylene (TCNE) was added to the methylene chloride solution. Absorption of the mixture onto silica gel and chromatography using 1:2 methylene chloride/hexanes as the eluent gave 0.8 g (90%) of the desired product as a white solid; m.p. >500°C. 18 M18 (00013) 6 4.24 (3,48), 5.90 (3,48), 5.94 (3,48), 6.94 (m,168), 7.35 (m,1611); 130 M18 (00013) 6 28.71, 50.58, 50.84, 124.07, 125.63, 125.84, 128.11, 137.11, 137.25, 58 138.45, 145.57, 145.80. Anal Calcd. for 070344: c,94.99; 11, 5.01. Found: 0, 94.83; 8, 5.17. 19. Anthracene Derivative 58 A solution of 0.89 g (1 mmol) of 84 and 0.3 g (1.3 mmol) of 000 in 150 mL of benzene was heated at reflux under argon for 16 hours. The solvent was removed and the residue was absorbed onto 10 g of 30-60 mesh silica gel. Heating the silica gel containing the reaction mixture at 250-300°0 under vacuum for 10 minutes and immediate chromatography using 2:1 hexanes/methylene chloride as the eluent gave 0.86 g (972) of the desired product as a yellow solid; m.p. >500°C. 18 NMR (002012) 6 6.31 (3,48), 6.42 (3,48), 6.97 (t,168), 7.24 (t,88), 7.54 (t,88); 130 1148 (002012) 6 50.61, 51.54, 119.98, 124.30, 125.04, 125.71, 127.57, 145.90, 146.30; mass spectrum nun/g (relative intensity) 883 (M+1, 15), 882 (M+,18), 207(24), 178(16), 149(54), 44(100). Anal; Calcd. for 070832: 0, 94.20; 8, 4.80. Found: C, 93.91; 8, 4.72. PART II BICYCLO [2.2.2] ALKYNES; REACTIVITY AND THE MECHANISM OF THE TRIMERIZATION is 1.80‘ Pref. y: INTRODUCTION Cyclononyne and cyclooctyne were the first small ring cycloalkynes to be synthesized, by Blomquist and co—workers about 30 years ago.“6 Since then a considerable amount of information regarding the existence and stability of smaller ring cycloalkynes has been reported." According to an arbitrary definition suggested by Krebs and Wilke, any cycloalkyne with an angle deformation larger than 10° is considered a strained cycloalkyne." Based on this definition, cyclononyne and cycloalkynes with smaller ring sizes fulfill this criterion. Cyclononyne and cyclooctyne are isolable compounds. Those unsubstituted cycloalkynes with fewer carbon atoms in their rings have only a transitory existence. There is no evidence as to the existence of cyclopropyne.‘8 Cycloalkynes can be generated by several methods. Matrix photolysis, in which the cycloalkyne is generated by the photolytic decomposition of the cyclopropenones, is used for spectroscopic [} O—LO +CO Oxidative decomposition of 1,2-hydrazones and 1-amino-1,2,3-triazoles studies.“9 is another method for generating cycloalkynes.5°'51 If a short-lived isolable cycloalkyne is to be prepared, lead tetraacetate is the preferred reagent for the oxidation, since the decomposition is fast 59 60 and takes place at low temperatures. Tetramethylcycloheptyne 85, the most strained known isolable cycloalkyne has been prepared by this method.52 N-NH . 2 PbCOAcli’ .11 N-NH2 -N2.-H20 85 In some cases, cycloalkynes have been generated by the thermal decomposition of the corresponding selenadiazoles.53 Pure cyclononyne 86 was prepared this way.54 Dehydrohalogenation of l-halocycloalkenes with strong bases, however, is the most frequently used method for generating these reactive intermediates. The following experimental observations usually provide the evidence for the existence of non-isolable cycloalkynes. (3) Addition of Nucleophiles Cycloalkynes are relatively strong electrophiles. Thus addition to the base is con-on in the preparation of these species by base- catalyzed elimination reactions.ss For example, 87 is assumed to form by addition of cyclooctyne to lithium piperidide in the following reaction.55 61 .“ . Li NO 9 .l 13ng 9 ."3 - 110,- 10 2. hydrolysis 8' Li N ui-c3H-pz j 37 Coupling products such as 32 are presumably formed through this mechanism (see p. 5 )- 30 3; 32 (b) Spectroscopy In these experiments, cycloalkynes are generated photolytically in a matrix at low temperatures and their spectra are recorded. For example, appearance of a new band at 2108 cm--1 in the IR spectrum obtained from the photolytic decomposition of 88 in a matrix at 20°11 has been assigned to the 0:2 stretching vibration in 89." :5» .1 :1 62 (C) Trapping Experiments Due to their structural strain, small ring cycloalkynes undergo [4+2] cycloaddition reactions with active dienes to give the corresponding cycloadducts.57.ss C H 6 S C H5 C H N 6 6 5 “"21" I i -—9 “Hz," Ill 4» S--) “Hz," 61' (H u C6H5 c6 5 NH?» c«"5 Cal‘s (d) Oliggmerization In the absence of any reactive reagent, strained cycloalkynes react with each other to form oligomeric species such as $.59 Kinetic investigations and isotope labeling experiments have also been used for probing the existence of strained cycloalkynes.5° (13' "‘ 0:0 Cg) ———O —.' -—-o . 8r Cycloalkynes possessing hydrogen atoms in the allylic positions, in the presence of strong bases, rearrange to the isomeric allenes, since an allene requires only three colinear carbon atoms.‘31 It is believed that the equilibrium shifts toward the allene as the ring size decreases.62 Labeling experiments have shown, for example that the addition products from the reaction of 1- halocyclohexene and 1- halocyclopentene with phenyllithium arise from the reaction of both allenic and acetylenic species with this reagent.63 51 80C Pre 111011 be u Comp refla quam 92.64 63 5.5—» 9"“ 621+ fi+éfi In this respect, bridged bicyclic systems have an advantage over simple cyclic systems. Due to the lack of any active allylic hydrogen atoms, the possibility of isomerization to an allene, as frequently encountered in the case of simple cycloalkynes, would be eliminated. Presence of the bridge should also impose considerable strain on the molecule and therefore a higher reactivity for the cycloalkynes would be expected. Only a few bridged bicycloalkyne systems have been reported. Compound 91 is reported to react with potassium t-butoxide in refluxing toluene to give the isomeric products 93 and 94 in quantitative yield, presumably through the bicycloalkyne intermediate 92.34 (it $3.9 .__... ‘12., 91 92 93 94 Vinyl halides % and 29, upon treatment with n-butyllithium at low temperatures in THF, form the lithiated species % and 30, respectively."5 . 5'7 trap; deriu Heatin‘ 3M4 33‘131,. 64 l t-BuLi t b C' H THF . Lu 95 A £35."; 29 30 The formation of these lithiated species has been proved by trapping with electrophiles. through which a variety of substituted derivatives of $ and 29 have been prepared. l'fl Cl i O E: 3r, o,cw,,su(cu-u,), Heating THF solutions of $ or 30 afforded the trimeric products 98 and 4, respectively, presumably via the cycloalkyne intermediates 97 and 31.”,57 6S Bicycloalkyne 31 has also been .trapped with several dienes, such as dimethylfuran, 1,3—dipheny1isobenzofuran and 1,l-dimethoxytetrachloro- cyclopentadiene to give the expected cycloadducts 99, 100, and 101, respectively.” There is no evidence for 97 being trapped by any diene, however. Cl Cl OMe \ CI 0M: / / Cl ———~ Q “as 'OMc 101 cu cu RESULTS AND DISCUSSION As part of a continuing study of bridged bicycloalkynes, regarding their occurrence, their dienophilic and electrophilic reactivity and the mechanism of the oligomerization of these species, l-chloro-l,4- dihydro—1,4-ethenonaphthalene 102 was prepared in 30—402 yield and gram quantities, by heating a suspension of benzenediazonium carboxylate in chlorobenzene at 55°C for 12-16 hours.67 I N? + 9 *0 9 CO 2 cu . II! The lithiation of 102 was achieved by treating a THF solution of this compound at' -42°C with n-butyllithium, to give 103. 103 is relatively stable at room temperature. Its formation was demonstrated by addition of ‘various electrophiles to THF solutions containing 103 at room temperature. '3‘“ ' A“ O n-BuLu/THF A 6 7 . Cl -42 0 Cl 102 . 103 1. Reaction of 103 With Iodine Addition of a solution of iodine in THF to a solution of 103 in THF resulted in the formation of 104. 66 67 :7 +0 ' cu Cl 103 104 The structure of 104 was confirmed by its mass and 18 NMR spectra. The mass spectrum of 104 showed a molecular ion peak at m/e 316. The 18 NMR spectrum showed two one-proton doublet of doublets at 6 4.85 and 4.95 for the two bridgehead protons, a set of doublet of doublets at 6 6.78 for the two vinylic protons, and two sets of doublet of doublets for the aromatic protons. 2. Reaction of 103 with Methyl Iodide Methyl iodide reacted with 103 at room temperature within one hour to give 2-chloro-3-methy1-l,4-dihydro-1,4-ethenonaphthalene 105 in 86* yield. 0 11 Mel ,1. ‘1 c' "‘9 Cl 103 105 Mass spectrum of 105 gave a molecular ion peak at m/e 202. The 18 NMR spectrum showed a singlet at 6 1.84 for the methyl protons, two sets of doublets of doublets at 6 4.56 and 4.67 for the bridgehead protons, and two sets of multiplets in the aromatic region for the vinylic and aromatic protons. The 13C NMR spectrum, which showed a peak at 6 16.89 for the methyl carbon atom, two peaks at 6 55.09 and 56.44 for the bridgehead carbon atoms and appropriate peaks for the rest of the carbon atoms, supported this structure. di Elf 68 3. Attempted Generation of a Bicycloalkyne from 103 Heating 3 solution of 103 in THF at reflux for two hours resulted in the disappearance of the starting material. Work up and purification of the reaction mixture gave a white solid in 47% yield, whose melting point, mass and 18 NMR spectra corresponded to those of naphthalene. Li A__@ 9 0 THF'~+' Cl . 103 Naphthalene has been shown to be one of the primary products formed from the pyrolysis of indanetrione in chlorobenzene at 500°C, evidently through the thermal decomposition of 102.68 We repeated this experiment by heating a neat sample of 102 at 350°C in a sealed tube. We found that naphthalene, l-chloronaphthalene and 2-chloronaphtha1ene were formed in a 1:0.8:2 ratio respectively, a result that is fairly consistent with those reported. Notice that both ethenyl bridges are lost in the pyrolysis of 102, whereas only the halogen-bearing bridge is eliminated from 103. Formation of naphthalene from 103 suggested an anion assisted cycloreversion reaction. Such reactions are well documented in the literature. The fragnentation of 2-pheny1 tetrahydrofuran and N ,N- dimethyl tetrahydropyrollidium iodide in the presence of strong bases are possibly the first examples of such reactions.°9:7° be Simil m"31110 69 (‘0 Ph ‘3 (1)88 —-—> Ph -C =CH2 + CH2=CH, K r @,Me Me\ 1 fix,“ fl Me/N-CH=CH, +CH,=CH, Oxyanion assisted [1,3]- and [3,3]-sigmatropic rearrangements and [4+2] retro-Diels-Alder reactions are other examples of cycloreversion reactions.71 Crime and coworkers predicted that cycloreversions become exothermic if they combine the formation of aromatic syst- with the release of ring strain.73 Accordingly, they found that the pair of 5- cyanocyclopentadiene adducts to benzene 106 and 107, upon treatment with LiTMP, cyclorevert within a minute to the cyanocyclopentadiene anion and benzene. / Na/K DME CN 106 CN 1 / Na/K Q 101 Similarly, Grutzner, gt”. 91.73 found that a mixture of syn- and anti—7- methoxy-7-pheny1norbornene in dimethoxyethane, when treated with sodium- Th grc Pro Prou Sing 7O potassium alloy, underwent cycloreversion at room temperature in 30 minutes to give the phenylcyclopentadiene anion 108. cmo 0.11. r on.“ ‘ Ns/K’ ‘ ’. mu: 1. J t room temp - 108 Whether naphthalene was a primary product resulting from the retro-Diels-Alder reaction of 103, or was formed via other pathways was resolved by trapping the missing fragment in this reaction by acetone. The 18 MIR spectrum of the crude reaction mixture, after complete evaporation of the solvent, showed a 1:1 mixture of naphthalene and another compound. This compound was separated and characterized as 109 based on its mass, 18 [MR and 13C MIR spectra. Me 1’0“ 50" “-—-» as + a W 0’ cu 2)(CH3)2CO cu 103 109 The mass spectrum of 109 showed a molecular ion peak at m/e 270. The 111 MIR spectrum showed a six proton sharp singlet at 6 1.48 for the methyl groups, two one-proton triplets at 6 4.71 and 4.78 for the bridgehead protons and two sets of multiplets for the six vinylic and aromatic protons. The peak for the hydroxyl proton appeared at 6 2.16 as a broad singlet. The 130 [MR spectrum of 109 showed a peak at 6 31.83 for the 71 two methyl carbon atoms, two peaks at 6 54.34 and 56.63 for the bridgehead carbon atoms, a small peak at 6 66.27 for the carbon atom bearing the hydroxy group and the appropriate peaks for the rest of the carbon atoms. Formation of 109 in a 1:1 ratio with naphthalene indicates that naphthalene is not a primary product in this reaction. More important, it suggests that the bridged bicycloalkyne 110 is first formed. .0 . >3 / Cl 103 "0 Upon formation, 110 reacts with one equivalent of 103 to give the coupling product, intermediate 111. Subsequently, 111 undergoes a retro-Diels-Alder reaction to give naphthalene and the acetylene derivative 112. 112 )3 03° Re Pr 10! BE in 8y: tol the reac \J [\J Reaction of 112 with acetone gives the lithium alkoxide derivative 113. Protonation of 113 during the work up then affords the observed product (:00 0 0 CFC _L. 109 (CH3)2C0 Cl 112 113 109. 4. Attempted Trapping of 110 With l,3-Dipheny1isobenzofuran An attempt to trap the bridged bicycloalkyne 110 *with 1,3— diphenylisobenzofuran failed to give any cycloadduct. Instead naphthalene was formed via the same sequence of reactions described above. The facile retro-Diels-Alder reaction of 111 prompted us to investigate the possibility of a similar reaction in the dibenzobicyclic toluene. The reaction mixture was heated at reflux for 12 hours. Since the T.l..0. analysis of the reaction mixture during the course of the reaction did not show any significant change, the reaction was stopped. »—«u 81 H 5! Di th 95} to unsr 102 Was bein1 73 The greater stability of 57 in comparison with 111 can be rationalized based on the resonance energy gained through the retro—Diels-Alder reaction. Assuming that breaking two bonds in both systems requires approximately the same amount of energy, than the energy gained through resonance by 111 amounts toz7‘ DREnaphthalene + DREbenzene = 33 - 21 = 12 Keel/mole By the same token, for 57: DREnaphthalene - ZDREbsnzene = 43 — 2 x 21 = l Keel/mole Thus, 111 is predicted to be about 11 Kcal/mole less stable than 57. Since in the pyrolysis of 102, via a.retro—Die13-Alder reaction, naphthalene and 2-chloronaphthalene are the only products expected, the 1-chloro-isomer must be a secondary product. It is possibly formed through the isomerization of the 2-chloro-isomer. The isomerization of l-chloronaphthalene to 2-chloronaphthalene and the reverse reaction, in the presence and absence of catalysts at elevated temperatures is well established.75 5. Reduction of 102 Based on the conclusion drawn from the above argument, we decided to block the retro-Diels-Alder reaction of 111 by reducing the unsubstituted vinylic double bond in 102. The selective reduction of 102 was achieved using hydrazine as the reducing agent.75 The reduction *was carried out according to the literature, the course of the reduction being monitored by 18 NMR spectroscopy in order to avoid over reduction. cu g] HgNNHg-HZO/MeOH a C' CuSO4/ 02 102 114 PI‘ 11135 The 462 . eth 74 Compound 114 was obtained as a colorless liquid in 88% yield and was characterized by its mass, 18 M18 and 130 MR spectra. The mass spectrum of 114 showed a molecular ion peak at m/e 190. The 111 NMR spectrum showed three sets of multiplets at 6 1.39, 1.57 and 1.74 for 1,1 and 2 protons of the saturated bridge, a multiplet at 6 3.87 for the bridgehead protons, a doublet of doublets for the vinyl proton at 6 6.24 and a multiplet at 6 7.06 for the four aromatic protons. The 13C NMR showed a peak at 6 26.49 for the saturated bridge carbon atoms, two peaks at 6 42.04 and 48.94 for the two bridgehead carbon atoms and the appropriate peaks for the remaining carbon atoms. 6. Synthesis of 1,2,3,4,5,6,7,8,9,10,11,12-dodecahydro- 1,4:5,8:9,lZ—trijo-benzenotriphenylene (116) Treating a solution of 114 in THF with n-butyllithium at -42°C followed by refluxing the reaction mixture for one hour gave a single product in 9% yield. This product was characterized as 116 based on its mass, 18 NMR and 130 NMR spectra. ’5 0. .70 " 9", 114 "5 116 The mass spectrum of this compound showed a molecular ion peak at nun/e 462. The 18 NMR spectrum showed a 12 proton singlet at 6 1.76 for the ethano-bridge hydrogens, a 6 proton singlet at 6 4.71 for the bridgehead de 75 hydrogens and two sets of doublet of doublets at 6 6.96 and 7.15 for the 12 aromatic protons. The 130 NMR spectrum showed a peak at 6 27.21 f0r the six equivalent methylene carbon atoms, a peak at 6 39.91 for the six methyne bridgehead carbon atoms, three peaks for the carbon atoms on the peripheral aromatic rings and a single peak for the central benzene ring. The 111 NMR and 13C NMR spectra are consistent with those predicted for the syn—syn-syn (03h) isomer. The yield of 116 was calculated based on the pure sample used for elemental analysis, which was obtained from several consecutive recrystallizations. Isolation of 116 not only is a strong indication for the occurrence of bridged bicycloalkyne 115, but also a proof that the resonance energy is a major contributor to the retro-Diels-Alder reaction of 111. In the previous chapters we have shown some evidence that the trimerization of bridged bicycloalkynes involves a stepwise pathway (optimizing the yield of 32, trapping of 111). The last step is the cyclization of the hexatriene moiety with the simultaneous loss of lithium chloride to give benzene. In order to examine this idea further, we thought the presence of bulky groups at the bridgehead positions might provide enough steric hinderance to obstruct this step. In this regard, we synthesized the mono-methyl substituted compounds 118 and 119. 7. Synthesis of 11-chloro-9-methy1-9,10-ethenoenthracene (118) and its l2-chloro isomer (119). The two isomeric compounds were obtained in a 1:1 ratio from the dehydrohalogenation of 117 in 942 yield." 0 o H. o 0 °' 11:2“ +0 cu + 0 cu CH C' 3 CH, 117 Ill "9 The isomers were separated by fractional recrystallization and their structures were confirmed by their mass, 111 MIR and 130 NMR spectra. The mass spectrum of both 118 and 119 showed a molecular ion peak at nun/e 252. The 111 [MR spectrum of 118 showed a three proton singlet at 6 2.15 for the methyl hydrogens, a doublet at 6 5.01 for the single bridgehead proton, a one-proton doublet at 6 6.93 for the vinyl hydrogen and two sets of multiplets for the eight aromatic protons. The 130 NMR spectrum of 118 showed a peak at 6 15.30 for the methyl carbon atom, a peak at 6 50.90 for the methyl substituted bridgehead carbon atom, a peak at 6 58.57 for the other bridgehead carbon atom and the appropriate peaks for the remaining carbon atoms. The 18 NMR spectrum of 119 showed a three- proton singlet at 6 2.20 for the methyl hydrogens, a one-proton singlet at 6 4.94 for the bridgehead hydrogen, a one-proton singlet at 6 6.41 for the vinyl hydrogen and two four-proton multiplets for the aromatic hydrogens. The 130 MIR spectrum of 119 showed a peak at 6 13.75 for the methyl carbon atom, a peak at 6 51.25 for the tertiary bridgehead carbon atom, a peak at 6 53.45 for the methyl-substituted bridgehead carbon atom and appropriate peaks for the rest of the carbon atoms. The assignment of the two structures 118 and 119 to the isomers was mainly based on the chemical shifts of the vinyl protons. An upfield shift 77 (0.52 ppm) of the vinyl proton in 119 was attributed to the shielding effect of the methyl group, due to their proximity. 8- TE§RR$9§ the chleelky e Generefied free 118 end 119 hymllfi:éiehspylisobenzefuran- Heating at reflux a THF solution of 120 and 121 prepared by treating a 1:1 mixture of 118 and 119 with n-butyllithium at —78°C, in the presence of 1,3-diphenylisobenzofuran for two hours afforded a single product 123 in 34% yield. 113 +119 ”it"; —> The mass spectrum of the coupling product 124 showed a molecular ion peak at m/e 468. The 18 NMR of 124 showed two three-proton singlets at 6 1.62 and 2.11 for the methyl groups, a one-proton doublet for the bridgehead hydrogen p—to the vinyl proton at 6 4.67, a one proton singlet for the bridgehead hydrogen Bbto the chlorine atom at 6 4.96 and a one-proton doublet at 6 6.14 for the vinyl proton. The 16 aromatic protons appeared as two sets of multiplets. The 13C NMR spectrum of 124 showed two peaks at 6 14.30 and 15.39 corresponding to the methyl carbon atoms, two peaks at 6 49.82 and 53.68 for the quaternary bridgehead carbon atoms, two peaks at 6 52.71 and 55.76 for the tertiary bridgehead carbon atoms, and the appropriate peaks for the remaining carbon atoms. The mass spectrum of 125 showed a molecular ion peak at m/e 648. The 18 NMR spectrum, as required by symmetry (03h) showed only four sets of peaks; 3 nine—proton singlet at 6 3.02 for the three methyl group hydrogens, a three-proton singlet at 6 6.73 for the bridgehead protons and two sets of 12 proton multiplets at 6 6.95 and 7.36 for the aromatic hydrogens. The 130 NMR of 122 spectrum showed a peak at 6 20.19 for the three methyl group carbon atoms, a peak at 6 48.70 for the three tertiary bridgehead carbon atoms, a peak at 6 51.82 for the three quaternary bridgehead carbon atoms and a total of seven peaks for the aromatic carbon atoms. A 3:1 mixture of 118 and 119 in THF, on the other hand, upon treatment with n-butyllithium at -78°C, followed by warming to room temperature and immediately refluxing for two hours, gave a mixture of three products 124, 126 and 127 in 72* overall yield. 79 Compound 123 was characterized by its mass, 18 NMR and 130 NMR spectra. The mass spectrum showed a molecular ion peak at m/e 486. The 111 NMR spectrum of 123 showed a three-proton singlet at 6 1.65 for the methyl hydrogens, a one-proton singlet at 6 5.24 for the bridgehead hydrogen and a 22-proton multiplet at 6 6.26-7.73 for the aromatic hydrogens. The 13C NMR spectrum showed a peak at 6 18.70 for the methyl carbon atom, a peak at 6 50.60 for the methyl-substituted bridgehead carbon atom, a peak at 6 51.78 for the bridgehead carbon atom bearing a hydrogen and a peak at 65.52 for the two phenyl-substituted bridgehead carbon atoms. Due to the unsymmetric structure of 123, the peaks beyond 100 ppm do not provide any useful information. Isolation of 123 in this reaction strongly indicates the involvement of a single intermediate, namely the bridged bicycloalkyne 122. 9. Trimerization of Bridged Bicycloalkyne 122 Stirring a THF solution of pure 121 prepared by treating a solution of par 117 in THF with n—butyllithium at -78°C, stirring for two hours at room temperature followed by heating at reflux for 30 minutes gave two products in 74" overall yield. The two products were separated and identified, based on their mass, 18 MIR and 130 NMR spectra, as 124 and 125. 0 e O 121 124 80 "6+1“ BuLi ATl-lF >3! ‘HOQ‘ Clcu‘ 124 126 The individual yields for 124, 126 and 127 were 42%, 14% and 44% respectively. The 18 MIR spectrum of 127 showed a six-proton doublet at 6 2.78, a six proton broad singlet at 6 3.02, four one-proton singlets at 6 6.02, 6.08, 6.71 and 6.73 and two sets of 16-proton multiplets at 6 6.96 and 6.37. The 111 MdR spectrum pointed to a tetrameric species; however, the possibility of such a species was ruled out by the mass spectrum which showed a molecular ion peak at m/e 648 (trimer). Based on a comparison of the 111 MIR spectrum of this product with that obtained for the symmetrical trimer, it was concluded that 127 was a 3:1 mixture of 128 and 125 (Figure 7). Unfortunately, attapts to separate these two isomers failed. Figure 7. Structural representation of the isomeric trimers 128 and 125 obtained from the trimerization of the bicycloalkyne 122. The structure of the coupling product 126 was confirmed by its mass, 18 MIR and 130 MIR spectra. The mass spectrum showed a molecular 81 ion peak at m/e 468. The 18 NMR spectrum showed two three-proton singlets at 6 2.14 and 2.16 for the two methyl groups, a one-proton singlet at 6 4.99 for the bridgehead hydrogen adjacent to the chlorine atom, a one-proton doublet for the other bridgehead hydrogen at 6 5.66, a one-proton doublet at 6 6.68 for the vinyl hydrogen and two 8-proton multiplets for the aromatic hydrogens. The 13C NMR spectrum showed six peaks for the sp3 hybridized carbon atoms as expected and a total of 16 peaks for the sp2 hybridized carbon atoms as required by symetry (plane). Based on the intermediacy of the cycloalkyne 122, four isomeric coupling products are expected for these reactions, 124, 126, 129, and 0 .c O W; s m 126 M... U " Q . Cl 130 130. The absence of the coupling product 129 and the exclusive formation 095%) of the trimer with 03h symmetry in the trimerization reaction of pure 121 suggests that: (a) only 129 is involved in the 82 formation of 125 (since 124 leads to 128) possibly due to steric hindrance, and (b) the addition of the cycloalkyne 122 to 129 must take place regiospecifically, since an indiscriminate attack of 122 on 126 would lead to the formation of both trimeric species. Further support for the above argument is the absence of 127 and the formation of a 3:1 mixture of 128 and 125, when a 3:1 mixture of 118 and 119 is used for this reaction. 10- Synthesis of 11:9h19r9:9.19:diye§hxl:9.1Q: ethenoanthracene (131) Although the presence of a methyl group at the bridgehead position of the cycloalkyne 122 might have been responsible for part of the unexpected results in the trimerization reactions, apparently it is not bulky enough to obstruct the cyclization process. Thus we decided to synthesize a more sterically hindered bridged bicycloalkyne precursor. In this regard, compound 131 was prepared by a procedure similar to that used for'118. The structure of 131 was confirmed by its mass and 18 MIR spectra. The mass spectrum of this compound showed a molecular ion peak at m/e 266. The 18 NMR spectrum showed two three-proton singlets at 6 2.08 and 2.13 for the methyl groups, a one-proton singlet at 6 6.55 for the vinyl hydrogen and two four-proton multiplets for the aromatic hydrogens . 11. Synthesis of 6,11-dimethyl-5,lZ-diphenyl-5,12-oxo- 6,11-o-benzenonaphthacene 134 Stirring a solution of 131 and 1.1 equivalent n-butyllithium in THF in the presence of 1,3-diphenyl isobenzofuran for two hours, 83 followed by heating the reaction mixture at reflux for another two hours afforded the expected cycloadduct 134 in 19% yield as a white solid. I33 134 The structure of this compound was confirmed by its mass, 18 NMR and 13C MIR spectra. The mass spectrum of 134 showed a molecular ion peak at m/e 500. The 18 NMR spectrum showed a six-proton singlet at 6 1.82 fer the methyl groups and six sets of multiplets at 6 6.64-7.73 for the 22 aromatic protons. The 13C NMR spectrum showed a peak at 6 15.53 for the two methyl carbon atoms, a. peak at 6 51.49 for the two methyl substituted bridgeheads, a peak at 6 66.65 for the oxygen-bridged carbon atoms and a total of 12 peaks for the 3p2 hybridized carbon atoms, as required by symmetry. 12. Attempted Trimerization of 133 Heating a solution of 132 in THF at reflux for two hours gave two products, 135 and 136 in 37% overall yield, and in individual yields of 26% and 11% respectively. 84 136 Compound 135 was characterized by its mass, 18 NMR and 130 NMR spectra. The mass spectrum of 135 showed a molecular ion peak at m/e 496. The 18 MIR spectrum showed four three proton singlets for the methyl group hydrogens, a one proton singlet for the vinyl hydrogen and four sets of multiplets for the 16 aromatic hydrogens. The 13C NMR spectrum showed four peaks for the methyl group carbon atoms, three peaks (overlap) for the four bridgehead carbon atoms and the appropriate peaks for the sp2 hybridized carbon atoms as required by symmetry (03). Compound 136 was characterized from its 18 NMR and 13C NMR spectra. The PR NMR spectrum of 136 showed six three-proton singlets for the six methyl groups, a one-proton singlet at 6 5.96 for the vinyl hydrogen and a 24-proton multiplet at 6 6.37—7.36 for the aromatic hydrogens. The 130 [MR spectrum showed six peaks for the six methyl group carbon atoms and 15 peaks for the sp2 hybridized carbon atoms. The peaks corresponding to the bridgehead carbon atoms were not obvious. Moreover, the mass spectrum of this compound did not show a molecular ion peak. 85 In conclusion, the absence of any trimer in the attempted trimerization of 133 and the isolation of the hexatriene derivative 136 in this experiment, as well as the other results obtained in the course of this study, strongly suggests a stepwise mechanism (p. 17) for the trimerization of the [2.2.2]bicycloalkyne systems, by the dehydrohalo— genation method. EXPERIMENTAL 1- z‘Ch10r0‘3‘iOd93114791929§9711§T§§89999929199199§w§194) To a solution of 1.9 g (10 mol) of 2-chloro-1,4-dihydro-l,4- ethenonaphthalene in 25 mL of anhydrous THF under argon at -78°C was added dropwise 4.4 mL (1.1 equivalent) of 2.5 M n-butyllithium in hexanes. The solution was stirred for two hours, brought to 0°C and stirred at this temperature for 30 minutes, then quenched with 1.40 g (11 mol) of iodine in THF. The solvent was removed and the brown oily residue was taken up in ether. The ether solution was washed with saturated sodium bisulfate solution, water, and saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the residue on a silica gel column using hexanes as eluent gave 2.93 g (93%) of 104 as an off- white solid; m.p. 85-86°C, 18 MIR (00013) 6 4.85 (dd,111), 4.95 (dd, 18), 6.78 (dd,28), 6.9 (dd,28), 7.16 (dd,28); 13C MIR (00013) 6 57.51, 61.66, 97.50, 122.91, 124.79, 137.92, 139.37, 144.58, 145.41, 147.91; mass spectrum gnu/e (relative intensity) 316 (10), 314 (24), 189 (17), 187 (52), 152 (100), 125 (8), 76 (15). A591, Calcd. for 01283011: 0, 45.80; 8, 2.56. Found: C, 45.68; 8, 2.51. 2 . 2-Chloro-3-methyl-1 , 4-dihydro-l , 4-ethenonaphtha1ene 195 To a solution of 0.38 g (2 -01) of 2-chloro-1,4-dihydro-l,4- ethenonaphthalene in 10 mL of anhydrous THF under argon at -78°C was added dropwise 1.0 mL (1.1 equivalent) of 2.2 M n-butyllithium in hexanes. The solution was stirred for two hours, brought to 0°C and stirred at this temperature for 30 minutes. Methyl iodide (excess) was added and the mixture was stirred for another hour. The solvent was 86 87 removed and the oily material was taken up in ether. The ether solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of solvent and chromatography of the oily residue on a silica gel column using hexanes as eluent gave 0.35 g (86X) of 105 as a colorless liquid which was crystallized from pentane upon cooling in the freezer; m.p. 62-6300; 1H NMR (CDCla) 6 1.84 (3,311), 4.56 (dd,18), 4.67 (dd,lH), 6.90 (m,4H), 7.17 (m,28); 13C NMR (CD013) 6 16.89, 55.09, 56.44, 122.49, 124.49, 129.66, 139.54, 145.19, 146.63; mass spectrum m/e (relative intensity) 204 (12), 202 (36), 168 (17), 167 (100), 166 (22), 165 (41), 152 (43). Qnal Calcd. for C13H11C1: C, 77.03; H, 5.47. Found: C, 76.94; H, 5.43. 3. Attempted trapping of 110 with 1,3—dipheny1isobenzofuran To a solution of 0.37 g (2.0 mmol) of 1,3-diphenylisobenzofuran in 25 mL of anhydrous THF at -78°C under argon was added dropwise 1.0 ml. (1.1 equivalent) of 2.2 M n-butyllithium in hexanes. The solution was stirred for two hours, brought to room temperature and heated at reflux for two hours. Methanol (1 mL) was added, the solvent was removed and the oily material was taken up in ether. The ether solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent was evaporated and the residue was chromatographed on a silica gel column using 3:1 hexanes/ether as eluent. Naphthalene and a compound whose molecular weight corresponded to that of isobenzofuran plus an atom of oxygen were the only products. 4. Attempted trimerization of 110 To a solution of 0.75 g (4 mmol) of 2-chloro-1,4-dihydro-1,4- ethenonaphthalene in 25 mL of anhydrous THF under argon at -78°C was 88 added dropwise 2 mL (1.1 equivalent) of 2.2 M n-butyllithium in hexanes. The reaction mixture was stirred for two hours, brought to room temperature and then heated at reflux for two hours. After cooling to room temperature the excess n-butyllithium was quenched with methanol. The solvent was removed and the residue was taken up in methylene chloride. The methylene chloride solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the dark brown residue on a silica gel column using 5:1 hexanes/methylene chloride as eluent gave 0.36 g (7096) of a white crystalline material; m.p. 80-82°C which was found to be naphthalene (mass spectrum, NMR). 5. Thermal decomposition of 2~chloro-1,4—dihydro-1,4— ethenonaphthalene A solution of 0.19 g (1.0 mol) of 2-chloro-1,4-dihydro-l,4- ethenonaphthalene in 0.5 mL of hexanes was flashed through a (5 mm diameter, 50 cm length) pyrex column packed with glass helices heated to 400°C. The material collected at the end of the column showed only recovered starting material. In a second experiment the same amount of the neat compound was melted and flashed through the column. The material collected at the end of the tube was found to be the starting material (G.C. , NMR). In a third experiment the same amount of the pure compound was placed in a small sealed tube and was heated at 350°C for 5 minutes. The tube was cooled to room temperature and opened. The dark brown material in the tube was dissolved in methylene chloride, absorbed onto a silica gel plate and eluted with hexanes. The polymeric materials were discarded, and the combined hexane soluble materials were analyzed by G.C. The G.C. results showed the presence of four different 89 compounds, the starting material, naphthalene, l-chloronaphthalene, and 2-chloronaphtha1ene with the 1:0.8:2 ratio respectively. 6- 2%Ch19r9-1.47dihx4§9:114-eth999992hth81ene.114 To a solution of 1.9 g (10 mmol) of 2-chloro-1,4—dihydro-1,4- ethenonaphthalene in 30 mL of 95% ethanol was added 1 mL (excess) of 'hydrazine monohydrate solution and a catalytic amount of cupric sulfate. The reaction mixture was stirred for eight hours while air was bubbling through. After the starting material completely disappeared (the course of the reaction was monitored by NMR) petroleum ether (100 mL), along with 50 mL of water, was added. The organic layer was separated, washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent was evaporated and the oily residue was vacuum pumped for 24 hours. Chromatography of this oily material on a silica gel column using pentane as the eluent gave 1.65 g (88*) of 114 as a colorless oil. 111 MIR (CDCla) 6 1.39 (m,28), 1.57 (m,111), 1.74 (m,18), 3.87 (m,28), 6.25 (dd,18), 7.06 (m,4H); 13C NMR (60013) 6 26.50, 42.00, 48.92, 122.87, 123.116, 125.65, 126.11, 126.70, 129.65, 137.90, 142.81, 143.46; mass spectrum m/e (relative intensity): 192 (5), 190 (3), 164 (33), 163 (14), 162 (100), 155 (11), 130 (10), 129 (16), 128 (11), 127 (19). Anal: Calcd. for C12811C1: C, 75.59; H, 5.81. Found: C, 75.42; H, 5.78. 7. Attempted trappigg of 115 with 1,3-dipheny1 isobenzofurag To a solution of 0.38 g (2.0 mmol) of 2-chloro-1,4-dihydro-l,4-— ethanonaphthalene and 0.60 g (2.2 mmol) of 2,3-diphenylisobenzofuran in 25 ml. of anhydrous THF at -78°C under argon was added dropwise 1.0 mL (1.1 equivalent) of 2.2 M n-butyllithium in hexanes. The reaction 90 mixture was stirred for two hours, brought to room temperature, and heated at reflux for two hours. Methanol (1 mL) was added. The solvent was removed and the oily material was taken up in ether. The ether solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent was evaporated and the residue was chromatographed on a silica gel column using 3:1 hexanes/ether as eluent. The only identifiable products were a trace of trimer and a compound whose molecular weight corresponded to that of isobenzofuran plus one atom of oxygen. 8. 1,2,3,4,5,6,7,8,9, 10, 11, 12-Dodecahydro-1,4,5.8,9. 12- t!i:9:h§9?§99triph9nylene 116 To a solution of 0.76 g (4 mol) of 2-chloro-1,4-dihydro-l,4- ethanonaphthalene in 25 ml. of anhydrous THF under argon at -78°C was added dropwise 2.0 mL (1.1 equivalent) of 2.2 M n-butyllithium in hexanes. The solution was stirred for two hours, brought to room temperature and heated at reflux for one hour. The solution was quenched with methanol and the solvent was removed. The residue was taken up in methylene chloride. The methylene chloride solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent was evaporated and the residue was chromatographed on a silica gel column using 2: 1 hexanes/chloroform as eluent. A yellow solid was obtained which was recrystallized several times from hexane-chloroform to afford 55 mg (9%) of a single trimer as a white solid; m.p. 314-316°C. 111 M (00013) 6 1.76 (s,1211), 4.71 (s,68), 6.96 (dd,611), 7.17 (dd,68); 13C NMR (CDCla) 6 27, 39.91, 123.60, 125.75, 134.16, 144.72; mass spectrum m/e (relative intensity), 462 (4), 91 434 (16), 378 (35), 278 (31), 254 (100), 189 (45), 129 (34). Anal. Calcd. for 0351130: C, 93.46; H, 6.53. Found: C, 93.27; H, 6.45. 9- 11:Ch1°r°-9‘methylrgllfirsthsaeayihrassnsi-12%9h19r9:9- asthxl:911979§hsn999§h§§99nsmllfiwand-119 To a solution of 5.8 g (20 mmol) of 11,12-dichloro-9-methy1-9,10- ethanoanthracene in 125 mL of THF was added 3.0 g (excess) of potassium t-butoxide. The reaction mixture was heated at reflux for 12 hours. The solvent was removed and the brown oily material was taken up in ether. The ether solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the residue on a silica gel column using hexanes as eluent gave 4.8 g (94%) of a 1:1 (1MB) mixture of two products. The two isomers were separated by fractional recrystallization from hexanes according to the following procedure. A concentrated solution of the mixture was left ton stand in the refrigerator for 3-5 days, upon which crystallization occurred. The solution was diluted with hexanes and filtered. The crystals collected were found to be enriched in the ll-chloro-isomer which was further recrystallized from hexanes to give the pure product. The second isomer was purified by removing the hexanes from the mother liquor and recrystallizing from methanol. ll-chloro-9-methyl-9,10-ethenoanthracene; m.p. 132-133°C, 18 mm (CD013) 6 2.15 (3,38), 5.01 (d,18), 6.93 (d,18), 6.97 (m,4H), 7.28 (m,4H); 130 NMR: (CDCla) 6 15.30, 50.90, 58.57, 120.40, 122.85, 124.69, 125.30, 136.90, 145.30, 145.91, 147.34; mass spectrum ~{I/g (relative intensity) 252 (13), 218 (17), 217 (100), 215 (25), 202 (34), 120 (26), 108 (17). Anal." Calcd. for C17H13012 C, “no-Wuuunuu 80.82; H, 5.14. Found: C, 80.77; H, 5.16. 92 12-0hloro—9-methy1-9,10-ethenoanthracene: m.p. 108- 109°C. 18 W (CD013) 6 2.20 (s,3H), 4.94 (3,111), 6.41 (s,1H), 7.00 (m,4H), 7.28 (m,4H); 13C W (CD013) 6 13.75, 51.25, 53.45, 120.85, 123.16, 124.58, 125.21, 134.54, 146.45, 147.50, 147.91; mass spectrum m/e (relative intensity), 252 (23), 218 (18), 217 (100), 216 (20), 215 (29), 202 (51), 192 (16). Anal Calcd. for 01781301: C, 80.82; H, 5.14. Found: C, 80.86; H, 5.12. 10- 9a12a’DiPhenylillZHXQFPTfifygihllfifingT9fi9ig111:9: yenzenonaphthacene 123 To a solution of 0.50 g (2 mol) of 11-ch10ro-9-methy1—9,10- ethenoanthracene and 0.60 g (2.2 mmol) of 1,3-dipheny1-isobenzofuran in 20 mL of anhydrous THF under argon at -78°C was added dropwise 1.0 ml. (1.1 equivalent) of 2.2 M n-butyllithium in hexanes. The reaction mixture was stirred for 2 hours, brought to room temperature and heated at reflux for two hours. A small amount of methanol was added (1 mL) and the solvent was removed. The residue was taken up in methylene chloride. The methylene chloride solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Removal of the solvent and chromatography of the residue on a silica gel colmnn using 1:2 hexane/methylene chloride as eluent gave 0.22 g of 123; m.p. 259—26000. 18 INF! (CD013) 6 1.65 (3,38), 5.24 (8,111), 6.26 (d,18), 6.72 (m,3H), 6.96 (m,7H), 7.09 (d,2H), 7.15 (m,28), 7.27 (d,28), 7.42 (m,3H), 7.58 (m,3H), 7.73 (d,28); 13C NMR (CD013) 6 18.71, 50.60, 51.78, 65.52, 120.40, 122.65, 124.89, 126.66, 127.47, 127.72, 128.03, 128.37, 129.10, 129.48, 130.25, 131.94, 132.54, 133.41, 140.34, 141.28, 142.68, 143.61, 146.12; mass spectrum m/g (relative intensity), 487(35), 486(98), 472(10), 471(17), 409(35), 294(28), 93 265(88), 194(30), 192(100), 191(59). Anal Calcd. for C37H260: c, 91.32; H, 5.38. Found: C, 91.26; 8, 5.33. 11- ‘Triystizaxigp of the bicycloalkyne 122 gsasrateé fr?! 11.894 lztghl9r979799tbx129.19:9th99939thr39399 To a solution of 5.1 g (20 mmol) of a mixture of 11 and lZ-chloro- 9—methy1-9,10-ethenoanthracene in 100 mL THF under argon at -78°C was added dropwise 8.8 mL (1.1 equivalent) of 2.5 M n-butyllithium in hexanes. The reaction mixture was stirred for one hour, brought to room temperature and heated at reflux for two hours. Methanol (2 mL) was added and the solvent was removed. The residue was taken up in methylene chloride, washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and elution of the solid material with 3:1 hexanes/methylene chloride on a silica gel column gave 3.4 g(78%) of a mixture of three products. Compound A: m.p. 209-21000; 18 [MR (CD013) 6 1.62 (3,38), 2.11 (3,38), 4.67 (d,lH), 4.94 (3,18), 6.14 (d,lH), 6.98 (m,88), 7.23 (m,88); 13C NMR (CD013) 6 14.30, 15.39, 49.82, 52.71, 53.68, 55.76, 119.96, 120.49, 122.78, 123.40, 124.28, 124.72, 125.07, 140.36, 141.10, 145.51, 145.59, 146.92, 148.36, 150.04; mass spectrum m/g (relative intensity). Anal; Calcd. for 03482501: 0, 87.10; H, 5.33. Found: C, 86.96; H, 5.30. Compound B: m.p. 259-26100, 18 M18 (0D013) 6 2.14 (3,38), 2.16 (3,38), 4.99 (3,18), 5.66 (d,lH), 6.68 (d,lH), 6.91 (m,88), 7.20 (m,88); 13C NMR (CD013) 6 15.45, 15.66, 50.47, 53.53, 56.26, 58.94, 120.28, 120.69, 123.43, 123.54, 124.57, 124.66, 125.16, 125.49, 141.63, 142.36, 144.72, 146.28, 147.78, 147.33, 147.77, 148.10, 148.72; mass spectrum 94 m/e (relative intensity) same as Compound A. Anal. Calcd. for 03482501: 0, 87.10; 8, 5.33. Found: C, 87.04; H, 5.38. Compound 0 was found to be a 3:1 mixture of isomeric trimers which could not be separated. However, the symmetrical trimer (03h) was formed exclusively when pure 11-chloro—isomer was used for trimerization. Compound 0 (03h) isomer; m.p. >500°C; 1H NMR (00013) 6 3.02 (3,98), 6.73 (3,38), 6.95 (m,128), 7.36 (m,128); 13C NMR (CD013) 6 20.19, 48.70, 121.72, 123.48.125.74, 146.21, 148.30; mass spectrum m/e (relative intensity) 649(30), 648(95), 633(43), 456(21), 441(29), 426(28), 262(16), 191(76), 85(100). Anal: Calcd. for 051833: 0, 94.45; H, 5.55. Found: 0, 94.33; H, 5.51. 12~ llzelllemfiil§lréimthy17.9: lo'ethenoanthracene 131 To a solution of 6.1 g (20 mmol) of 11,12-dichloro-9,10-dimethyl- 9,10-ethanoanthracene in 125 mL THF was added 3.0 g (excess) of potassium t-butoxide. The reaction mixture was heated at reflux for 16 hours. The solvent was removed and the residue was taken up in ether. The ether solution was washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of solvent and chromatography of the oily material on a silica gel column using hexanes as eluent gave 4.9 g (91%) of 131 as a white solid; m.p. 106-107°C, 18 NMR (CD013) 6 2.08 (3,38), 2.12 (3,38), 6.55 (3,18), 6.99 (m,48), 7.24 (m,48). 13. Attempted Trimerization of ll-chloro-9,10-dimethy1— 9,10—ethenoanthracene To a solution of 1.35 g (5 mmol) of ll-chloro—9,10-dimethy1-9,10- ethenoanthracene in 50 mL of anhydrous THF at -78°C under argon was 95 added dropwise 2.2 mL (1.1 equivalent) of 2.5 M n-butyllithium in hexanes. The reaction mixture was stirred for one hour, brought to room temperature and heated at reflux for two hours. Methanol (lmL) was added. The solvent was removed and the dark brown material was taken up in methylene chloride. The methylene chloride solution was washed with water, saturated sodium chloride solution .and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the residue on a silica gel column using 3:1 hexanes, methylene chloride gave compounds A and B as the major products. Compound A: 320 mg (26%), m.p. 263-26400; lH NMR (CD013) 6 1.38 (3,38), 1.44 (3,38), 2.05 (3,38), 2.09 (3,38), 6.07 (3,18), 7.07 (m,168); 130 NMR (0D013) 6 13.90, 14.74, 15.33, 15.83, 49.49, 52.55, 52.64, 119.84, 120.11, 120.60, 124.29, 124.83, 125.20, 142.49, 145.11, 149.48, 150.02, 151.04; mass spectrum m/g (relative intensity) 498(0.3), 497(0.3), 496(0.9), 373(1.2), 207(19), 206(100), 191(14). A9991 Calcd. for 03382901: 0, 87.02; H, 5.83. Found: 0, 86.95; H, 5.86. Compound 8: 130 mg (11%), m.p. 378-38000; 18 NMR (CD013) 6 1.28 (3,38), 1.33 (3,38), 1.51 (3,38), 1.58 (3,38), 1.79 (3,38), 1.82 (3,38), 5.96 (3,18), 6.91 (m, 148); 130 M18 (CD013) 6 45.38, 47.85, 48.59, 49.81, 50.59,52.11, 123.17, 123.96, 124.21, 124.67, 125.36, 126.37, 126.66, 127.20, 128.92, 130.75, 140.16, 142.04, 143.37, 144.01, 144.54; no mass spectrum could be obtained. A5319 Calcd. for Cs483301.820: C, 86.37; H, 5.80. Found: C, 86.28; 8, 5.77. 14. 6.11-Dimethyl-5.12-dipheny1-5.1?:9§9:§.11:9: benzenotetracene 134 To a solution of 0.54 g (2 mmol) of 11-chloro-9,10-dimethy1-9,10- ethenoanthracene and 0.60 g (2.2 mmol) of 1,3-dipheny1isobenzofuran in 96 25 mL of anhydrous THF at -78°C under argon was added dropwise 1.0 mL (1.1 equivalent) of 2.2 M n-butyllithium in hexanes. The mixture was stirred for two hours, brought to room temperature and heated at reflux for another two hours. The reaction mixture was cooled to room temperature, quenched with a small amount of methanol and the solvent was removed. The residue was taken up in methylene chloride, washed with water, saturated sodium chloride solution and dried over anhydrous magnesium sulfate. Evaporation of the solvent and chromatography of the residue on a silica gel column using 2:1 hexanes/methylene chloride as eluent gave 190 mg (19%) of 134 as a white solid; m.p. 306-308°0, 18 1018 (CD013) 6 1.82 (3,68), 6.64 (m,48), 6.75 (q,28), 7.11 (m,48), 7.31 (9,28), 7.43 (m,68), 7.73 (m,48); ‘30 N48 (0D013) 6 15.53, 51.49, 66.65, 120.83, 123.12, 124.79, 125.22, 125.41, 129.10, 130.00, 130.93, 135.27, 148.10, 149.59, 150.83; mass spectrum m/g (relative intensity) 501(2), 500(6), 396(5), 395(15), 365(8), 194(10), 270(100), 105(35). 99519“ 0a1cd.for 0338230: 0, 91.16; H, 5.63. Found: 0, 91.11; H, 5.61. 15. 2—0hloro-3-[1-(2-methy1-1-butyne-2-01)]-1,4-dihydro-1,4- ethenonaphthalene (109) To a solution of 0.38 g (2 mol) of 2-chloro-1,4-dihydro-1,4- ethenonaphthalene was added 0.9 ml. (1.1 equivalent) of 2.5 M n- butyllithium in hexane at -78°C under argon. The reaction mixture was stirred for one hour, brought to room temperature, stirred at this temperature for another hour and heated at reflux for two hours. To this was added 1 mL of acetone and the mixture was heated at reflux for an additional two hours. The solvent was removed by steam distillation. Chromatography of the remaining residue on a silica gel plate using 3:1 hexanes/ methylene chloride as eluent gave 0.12 g (47%) of naphthalene 97 and 0.24 g (4436) of 106 as a yellow gum. 18 M48 (CD013) 6 1.48 (2,68), 2.16 (broad 3,18), 4.71 (t,18), 4.78 (6,18), 6.90 (m,48), 7.18 (m,28); 130 NMR (CD013) 6 31.83, 54.34, 56.63, 66.27, 123.71, 125.83, 126.11, 128.23, 138.81, 140.06, 145.45, 146.12; mass spectrum, m/g (relative intensity) 272 (4), 270 (16), 191 (15), 176 (15), 128 (35), 86 (31), 84 (46), 43 (100). Anal. Calcd. for 017815010: 0, 75.41; H, 5.58. Found: C, 75.32; H, 5.60. APPEND ICES APPENDIX 1 The name "iptycene" emphasizes the relationship between these compounds and the parent compound triptycene. The prefixes tri, pent, hept, etc. indicate the number of separated arene planes. Besides the prefix, three descriptors enclosed in a bracket are used to precisely define these structures. The first descriptor, a series of numbers, defines the arene ring system (1,2,3, etc. for benzenoid, naphthalenoid, anthracenoid, etc. respectively). The second descriptors are English alphabet letters (a,b amd (a . . .), and are placed at the upper and lower right side of the first descriptors. The upper index refers to the bonds to which the sp3 carbon atoms are attached; and the lower index indicates the bonds involved in ring fusions. Thus, compounds 2, 3, 33 and 77 are [1.1.13.1.1] pentiptycene, [l.1.1°.1.1] pentiptycene, [1.1.3bbb.l.1] pentiptycene and [1.1.3'cb.l.1] pentiptycene, respectively. 33 77 98 99 Accordingly, "supertriptycene" 24 is named as [1.1.la»c.1.l.la’c- .13’¢.1.1.1.1.1.1.1.1] pentadecaiptycene. 24 A simplified or abbreviated definition is possible for the compounds listed in Table I. If the sites of possible fusions on the parent compound triptycene 1 can be designated by the alphabet letters a,b,c, and their primes and seconds. Thus, compounds 2, 3 and 24 can simply be defined as a—pentiptycene, b-pentiptycene and a,c,al,c1,a",c"- pentadecaiptycene. APPENDIX 2 Crystallographic Data for Compound Crystals of 66, 032822012, are triclinic; space group p-l; a=8.229, b=10.641, c=6.837 A, =102.22°, =102.22°, =77.34°; Z-l; M- 477.44; Pc=1.410 g cm—3. Lattice dimensions were determined using a Picker-FACS-I diffractometer and MoKl ( =0.71073 A) radiation. Intensity data were measured using MoK radiation (2 max: 45°) yielding 2964 total collected data and, based on I > 25 (I), 1482 observed data. The data were reduced73; the structures were solved by direct methods79; and the refinement was by full-matrix least-squares techniques. The final 8 values were 81 = 0.032 and 82 = 0.038. The final difference Fourier map showed densities ranging from +0.221 to -0.248 with no indication of missing or incorrectly placed atoms. Bond lengths and bond angles are given in the following pages (Table 4 and 5). 100 101 FiEUre 8. Crystal structure and the packing pattern of the crystals of compound 66. 102 Bond distances (K) for 66. Thbh34. Atoml AtomZ Distance C11 C11 1.826(2) C1 C2 1.384(5) Cl C10a 1.388(4) C2 C3 1.373(4) C3 C4 1.393(4) C4 C4a 1.384(4) C4a C5 1.525(4) C4a C10a 1.393(4) C5 CSa 1.524(3) C5 C12 1.530(4) CSa C6 1.378(4) CSa C9a 1.396(4) C6 C7 1.394(4) C7 C8 1.377(5) C8 C9 1.379(4) C9 C9a 1.384(4) C9a C10 1.519(4) C10 C10a 1.514(4) C10 C11 1.549(4) C11 C12 1.513(3) C1 81 0.96(3) C2 82 0.96(3) c3 83 0.92(3) C4 84 O.94(2) 103 Atoml AtomZ Distance C5 85 0.88(2) C6 H6 O.93(2) c7 87 0.91(3) C8 88 0.88(3) C9 H9 0.84(3) C10 810 0.88(2) C11 . 811 l.13(3) Numbers in parentheses are estimated standard deviations in the least significant digits. 104 Table 5 Bond Angles (°) for 66. Atoml Atom2 Atom3 Angle C2 C1 C10a 119.0(3) C1 C2 C3 121.0(3) C2 C3 C4 120.7(3) C3 C4 C4a 118.4(3) C4 C4a C5 126.0(2) C4 C4a C10a 120.9(2) CS C4a C10a 113.0(2) C4a C5 CSa 106.6(2) C4a C5 C12 108.8(2) CSa C5 C12 104.0(2) C5 C5a C6 126.6(2) C5 CSa C9a 112.8(2) C6 CSa C9a 120.6(2) CSa C6 C7 119.0(3) C6 C7 C8 120.3(3) C7 C8 C9 120.8(3) C8 C9 C9a 119.4(3) CSa C9a C9 119.9(2) CSa C9a C10 113.3(2) C9 C9a C10 126.8(2) C9a C10 C10a 107.3(2) C9a C10 C11 105.6(2) C10a C10 C11 107.0(2) C1 C10a C4a 120.0(3) C1 C10a C10 126.8(2) 105 Atoml Atom2 Atom3 Angle C4a C10a C10 113.3(2) C11 C11 C10 108.8(2) C11 C11 C12 110.7(2) C10 C11 C12 109.5(2) C5 C12 C11 111.2(2) C2 C1 H1 123.(2) C10a Cl H1 118.(2) C1 C2 H2 119.(2) C3 C2 H2 120.(2) C2 C3 H3 118.(1) C4 C3 H3 121.(1) C3 C4 H4 120.(2) C4a C4 H4 122.(2) C4a CS HS 112.(1) CSa CS H5 112.(1) C12 C5 HS 113.(2) C5a C6 H6 120.(1) C7 C6 86 121.(l) C6 C7 H7 122.(2) C8 C7 H7 118.(2) C7 C8 88 116.(2) C9 C8 HS 123.(2) C8 C9 89 117.(2) C9a C9 89 124.(2) 106 Atoml AtomZ Atom3 Angle C9a C10 810 114.(1) C10a C10 H10 113.(2) C11 C10 H10 109.(2) C11 C11 H11 101.(1) C10 C11 H11 110.(1) C12 C11 H11 ll6.(1) Numbers in parentheses are estimated standard deviations in the least significant digits. 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C m..— BN n,n 8... “r LLQn nm 0.0 no .6 n... . ol— m. .L .L i) \L a. \ W4) .mNH 9509.50 mo 2:30on mzz = 3.3 n. 3. m... 3.~ m.~ a.n win ... .c . . . . . w. . «.2 «JJJJJJJjj. s _m an nm as no a... .. an , . 118 .mm~ cssoasoo mo asnuoeam :22 IA 3:2 0mm .om shaman {L P rr’? r}; rhhrFrbr PP DP) Pb? ’9.” PP’r P'r [ L} P h ? rhhbhbb P _ — — ’NPP.I~+?L>FE 119 x . .\ .mmd pom mmd msmsmcu edsoaomw may mo ossuxfle mu~ yo assuowam mzz mA 3:: 0mm .HN mssmmm I.O . n a. n. a n n n a n «A 2.: mi 28 n.n 0.3 a,c I... n... C.. 0.. h))>)_))))h))b)b)>)bbb)llbl)-II&I})IIILII)I\ L*+» 1}?» L L I0. 7 r .eMa 33333332636 3:5 so esssooam m2: =2 3:: com .NN mesmna CLL n n 0.0 no In n.n 0.0 “.0 I.r fl... 0.. flu .0 a- n a. n. a~ r rbrrfPhPr bfbbilrhr Llhrhrrhr>rrr>|rfrhrrF|rbrrr+—r’?rh1)*?>hF>7>~>Lr>1b 4 §-..‘- d. 121 mm; .«0 Escuooam E22 :2 NI: omm .mm 6.5mm..— Ol I. O. W. IN nu .n an I! at In W” ._0 n.u OP .flP CD hhrP5hrr>P~rrhbhrf>rhrrrrhthrhr*rPhDPPrHrbrbhPPP'FPr8rh>bTLF—NDPLDH8»?>~IlblhlmIDbPP’ [1| '1." 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