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W: bu .. ...._ ,1" -~-~--’-.21:‘.___ "' ’J_."'IF3-§F , is MICHIGAN STATE I III/IZIIII RABIES IIIIIIIIIIIII IIIIIIII I II 76874 II This is to certify that the dissertation entitled Applications of Ferrodenylsulfide-Based Catalysts in Selective Hydrogenations and Asymmetric Cross-coupling Reactions presented by Chun-Hsiung Wang has been accepted towards fulfillment of the requirements for Ph. D. degree in Chemistry Major professor MS U is an Affirmative Action/Equal Opportunity Institution 0-12771 __._.— r LIBRARY Michigan State University K. PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before date due. DATE DUE DATE DUE DATE DUE L‘I IE EDDI— MSU Is An Affirmative Action/Equal Opportunity Institution cmmr APPLICATIONS OF FERROCENYLSULFIDE-BASED CATALYSTS IN SELECTIVE HYDROGENATIONS AND ASYMMETRIC CROSS- COUPLING REACTIONS By Chun-Hsiung Wang A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Chemistry 1991 ABSTRACT APPLICATIONS OF FERROCENYISULFIDE-BASED CATALYSTS IN SELECTIVE HYDROGENATIONS AND ASYMME'IRIC CROSS-COUPLING REACTIONS By Chun-Hsiung Wang New chiral and achiral ferrocenylamine sulfides of the type (C5H5)Fe(C5H3)[CH2NR2][SR’], R=Et. n-Pr, R’= Me, Et. p-tolyl, p- chlorophenyl and (R,S)- or (S,R)-(C5H5)Fe(C5H3)[CHMeNRz][SR’], R=Et, n-Pr, R’= Me, Et, i-Pr have been prepared by first converting corresponding 1-dimethylaminoethyl-2-alkylthio ferrocene to ferrocenylacetate derivatives followed by reaction with dimethylamine or di-n-propylamine. These compounds are air-stable and were characterized by spectroscopic techniques such as 1H and 13C NMR, infrared and mass spectroscopy as well as elemental analysis. These ferrocenylamine thioethers readily chelate palladium chloride to form the chiral and achiral heterobimetallic complexes, (C5H5)Fe(C5H3)[CI-IR"NR2][SR’][PdC12], (R=Et. n-Pr, R’=Me, Et, p-tolyl, pochlorophenyl, R”=H), (R=Et, n-Pr, R’= Me, Et. i-Pr, R”=Me). 1H NMR, IR, MS and elemental analyses were obtained for these complexes. The catalytic applications of these complexes to the hydrogenation of conjugated-dienes and phenylacetylenes were examined. High chemo- and regioselectivities have been achieved with superior activities and 100% conversions in most cases. A l-2-disubstituted-ferrocenylsulfide ligand and it’s palladium and platinum complexes were synthesized in order to compare the influence the substituents of the catalysts exerted on hydrogenations of conjugated-dienes. It reveals that both the amino- and sulfido- substituents have effects on the hydrogenation reaction. Changes in the amino group environment dominate. A plausible catalytic pathway is proposed for the hydrogenation of phenylacetylenes. In situ rhodium catalysts were prepared by using chiral ferrocenylamine sulfide ligands to investigate the asymmetric induction of prochiral aminoacids. Reasonably good enantiomeric excess (ee) were obtained by measuring the optical rotations of the hydrogenated products on a polarimeter. A possible mechanism of asymmetric hydrogenation is proposed. These new palladium complexes were also tested on the asymmetric Grignard cross-coupling reaction. Results have shown that the optical yields depended on the surroundings around the nitrogen atom within the catalysts. ACKNOWLEDGEMENTS I would like to acknowledge the contribution of Professor Carl H. Brubaker, whose professional assistance and inspiration were indispensable. I would also like to thank Dr. H. A. Eick, Dr. C. K. Chang and Dr. M. W. Rathke for many helpful discussions and Dr. C. K. Lai, Dr. A. A. Naiini, Dr. A. Hussein for their friendship. Finally, I wish to express my deepest appreciation and thanks to my grandmother and my parents for their love, encouragement and understanding. II. TABLE OF CONTENTS INTRODUCTION ......................... EXPERIMENTAL ......................... Preparation of Ligands ..................... a. Achiral Ligands ........................ (1)- (2). (3). (4)- (5). (6). (7). l-Diethylaminomethyl-2-methylthioferrocene (37, R=Et, R'=Me, R"=H) ................... 1-Diethylaminomethyl-2-ethylthioferrocene (38, R=Et, R'=Et, R"=H) ........ ~ ............ l-Diethylaminomethyl-2-(4-chlorophenyl)thio- ferrocene (39, R=Et, R'=4-chlorophenyl, R"=H) ...... l-Diethy1aminomethyl-2-(4-methylphenyl)thio- ferrocene (40, R=Et, R'=4-methylphenyl, R"=H) . ..... 1-Di-n-propylaminomethyl-2-methylthioferrocene (41, R=n-Pr, R'=Me, R"=H) ................. 1-Di-n-propylaminomethyl-2-ethylthioferrocene (42, R=n-Pr, R'=Et, R"=H) .................. l-Di-i-propylaminomethyl-Z-ethylthioferrocene (43, R=i-Pr, R'=Et, R"=H) .................. IV PAGE 1 15 16 16 16 17 .18 18 .19 20 20 (8). 1-Di-i-butylaminomethyl-2-ethylthioferrocene (44, R=n-Pr, R'=Me, R"=H) .................. 2 1 (9). 1-Diphenylaminomethyl-2-p-chlorophenylthio- ferrocene (45, R=Ph, R"=p-chlorophenyl, R'=H) ...... 22 (10). l-Ethylmethylaminomethyl-2-methylthio- ferrocene (46, R=NMeEt, R'=Me, R"=H) .......... 2 2 b. Chiral Ligands ......................... 2 4 (1). (S,R)-1-(1-Diethylaminoethyl)-2-methylthio- ferrocene ((S,R)-50, R=Et, R’=Me, R”=Me) ......... 24 (2). (S,R)-1-(l-Di-n-propylaminoethyl)-2-methylthio- ferrocene ((S,R)-51, R=n-Pr, R’=Me, R”=Me) ........ 25 (3). (R,S)-1-(1-Diethylaminoethyl)-2-ethylthio- ferrocene ((R,S)-52, R=Et, R’=Et, R”=Me) .......... 2 5 (4). (R,S)-1-(l-Diethylaminoethyl)-2—methylthio— ferrocene ((R,S)-53, R=n-Pr, R’=Et, R"=Me) ........ 26 (5). (R,S)-1o(1-Diethylaminoethyl)-2-isopropy1thio- ferrocene ((R,S)-S4, R=Et, R’=i-Pr, R”=Mc) ........ 27 (6). (R,S)-1-(1-Di-n-propylaminoethyl)-2-i-propylthio- ferrocene ((R,S)-55, R=n-Pr, R’=i-Pr, R”=Me) ....... 28 c. Synthesis of Ferrocenylsulfide Ligands ............ 2 9 1. 1~Methylthio-Z-ethylthiomethylferrocene 56 ....... 2 9 . Preparation of Palladium and Platinum Complexes . . . . . . 3 O (1). l-Diethylaminomethyl-2-methylthioferrocenyl palladium chloride (57, R=Et, R'=Me, R"=H) ........ 3 O (2). l-Diethylaminomethyl-2-ethylthioferrocenyl palladium chloride (58, R=Et, R'=Et, R"=H) ......... 3 0 V (3). 1-Diethylaminomethyl-2-(4-chlorophenyl)thio- ferrocenyl palladium chloride (59, R=Et, R'=4-chlorophenyl, R"=H) .................. 3 1 (4). 1-Diethylaminomethyl-2-(4-methylphenyl)thio- ferrocenyl palladium chloride (60, R=Et, R'=4-methylphenyl, R"=H) .................. 3 2 (5). l-Di-n-propylaminomethyl-2-methylthioferrocenyl palladium chloride (61, R=n-Pr, R'=Me, R”=H) ....... 3 2 (6). l-Di-n-propylaminomethyl-2-ethylthioferrocenyl palladium chloride (62, R=n-Pr, R'=Et, R"=H) ........ 3 3 (7). l-Ethylmethylaminomethyl-2-methylthio-ferrocenyl palladium chloride (63, R=NMeEt, R'=Et, R"=H) ...... 3 4 (8). l-Methylthio-2-ethylthiomethylferrocenyl palladium chloride (64) ................... 34 (9). 1-Methylthio-2-ethylthiomethylferrocenyl platinum chloride (65) ................... 35 (10). (S,R)-1-(l-Dicthylaminoethyl)-2-methylthio- ferrocenyl palladium chloride ((S,R)-66, R=Et, R’=Me, R”=Me) ....................... 3 6 (11). (S,R)-l-(1~Di-n-propylaminoethyl)-2-methylthio- ferrocenyl palladium chloride ((S,R)-67, R=n-Pr, R’=Me, R”=Me) ....................... 3 6 (12). (R,S)-1-(l-Diethylaminoethyl)-2-ethylthio- ferrocenyl palladium chloride ((R,S)-68, R=Et, R’=Et, R”=Me) ........................ 3 7 (l3). (R,S)-l-(1-Diethylaminoethyl)-2-methylthio- ferrocenyl palladium chloride ((R,S)-69, R=n-Pr, R’=Et, R”=Me) ........................ 3 8 VI (14). (R,S)-1-(1-Diethylaminoethyl)-2-i-propylthio- ferrocenyl palladium chloride ((R,S)-70, R=Et, R’=i-Pr, R”=Me) ....................... 3 8 (15). (R,S)—l-(l~Di-n-propylaminoethyl)-2-i-propylthio- ferrocenyl palladium chloride ((R,S)-7l, R=n-Pr, R’=i-Pr, R”=Me) ....................... 3 9 C. General Procedure for Hydrogenation Reactions . . . . . . . . 4 O (l). 1,3-Cyclooctadiene ..................... 4O (2). Acrylic acid ......................... 4 0 (3). Phenylacetylenes ...................... 4 O (4). Asymmetric hydrogenation of aminoacids . . . . . . . . 40 D. Asymmetric Grignard Cross-Coupling Reaction ......... 4 2 Oxidation of 4-phenyl-l-pentene to methyl-3-phenylbutyrate .................... 4 2 III. RESULTS AND DISCUSSION ................... 4 4 A. Synthesis of Ferrocenylamine Catalysts ............. 4 4 1. Synthesis and characterization of ferrocenylamine ligands 44 (1). Ferrocenylamine sulfides .................. 4 4 (2). Synthesis of ferrocenyldisulfide ligand . . . . . . . . . . 67 2. Preparation of palladium and platinum complexes . . . . . 7 3 B. Selective Hydrogenation ..................... 8 9 a. Homogeneous hydrogenation of 1,3-cyclooctadiene . . . . 8 9 b. Hydrogenation of acrylic acid ................ 9 8 VII c. Hydrogenation of phenylacetylenes ............. 100 (1). Hydrogenation of phenylacetylene to ethylbenzene ........................ 1 0 0 (2). Selective hydrogenation of phenylacetylene to styrene .......................... 102 (a). Effect of catalysts ..................... 102 (b). Solvent effects ...................... 104 (c). Selective hydrogenation of disubstituted acetylenes ......................... 107 (d). Proposed mechanism for hydrogenation of phenylacetylenes ..................... 109 (e). Concluding remarks ................... l 14 C. Asymmetric Hydrogenation of Aminoacid Precursors . . . . . 1 16 Proposed mechanism ...................... 120 Concluding remarks ....................... 12 2 D. Asymmetric Grignard Cross-Coupling Reaction . . . . . . . . . 123 IV. APPENDIX ............................ l 2 8 V . REFERENCES ........................... 17 6 VIII LIST OF TABLES TABLE PAGE 1. 300 MHz 1H NMR data for compounds (37-46) in CDC13 at room temperature; 5 ppm (Hz) ................ 4 7 2. 300 MHz 1H NMR data for compounds ((S,R)-50-(R,S)-55) in CDC13 at room temperature; 5 ppm (Hz) ........... 4 9 3. Change in chemical shifts for achiral ferrocenylamine sulfides ..................... 5 2 4. Change in chemical shifts for chiral ferrocenylamine sulfides ..................... 5 3 5. 72.5 MHz 13C NMR spectra for ligands 37-46, 56 ....... 55 6. 72.5 MHz 13C NMR spectra for ligands (S,R)-50-(R,S)-55 . . 57 7. FTIR spectra of compounds 37-46, 56 ............. 60 8. FTTR spectra of compounds (S,R)-50-(R,S)-55 ........ 61 9. 300 MHz 1H NMR data for compounds (57-65) in CDC13 at room temperature; 5 ppm (Hz) ................ 7 6 10. 300 MHz 1H NMR data for compounds ((S,R)-66-(R,S)-7l) in CDC13 at room temperature; 5 ppm (Hz) .......... 7 7 11. FTIR spectra of complexes 57-(R,S)-7l ........... 8 4 12. Analytical data for ligands 37-56 .............. 87 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. Yield, melting point, color, and analytical data of complexes 57 -(R,S ) -7 l .................... Selective hydrogenation of 1,3-cyclooctadiene by various achiral complexes (C5H5)Fe(C5H3)(CH2NR2)(SR’)PdC12 at 62 psi hydrogen pressure ................... Selective hydrogenation of 1,3-cyclooctadiene by various chiral complexes (C5H5)Fe(C5H3)(CHMeNR2)(SR’)PdClz at 62 psi hydrogen pressure ................... Hydrogenation of 1,3-cyclooctadiene, effect of pressure . Selective homogeneous hydrogenation of dienes to monoenes, comparison of the catalytic activity . Hydrogenation of acrylic acid at 80 psi H2 pressure ..... Hydrogenation of phenylacetylene to ethylbenzene . Hydrogenation of phenylacetylene to styrene, effect of catalysts ....................... Hydrogenation of phenylacetylene to styrene, effect of solvents ........................ Hydrogenation of diphenylacetylene ............. Hydrogenation of methylphenylacetylene . Hydrogenation of ethylphenylacetylcne and t-butylphenylacetylene .................... Hydrogenation of phenylacetylenes by using 58 as catalyst ......................... Asymmetric hydrogenation of aminoacid precussors by in situ rhodium catalysts ................... 88 92 93 .94 96 99 101 103 106 108 110 .111 .112 .117 27. Asymmetric Gringard cross-coupling of chloroethylbenzene with allylmagnesium halides by new chiral ferrocenylamine sulfide catalysts . . . . . . . 126 XI LIST OF FIGURES FIGURE PAGE 1. 300MHleNMRspectrum of 38 ................ 50 2. 300 MHz 1H NMR spectrum of (R,S)-52 ............ 51 3. Broad band decoupled 13C NMR spectrum of 37 ....... 5 8 4. DEPT 13C NMR spectrum of 37 ................. 59 5. Mid IR spectrum of compound (S ,R)-50 ............ 62 6. CD spectra of (S,R)-51, (R,S)-54 and (R,S)-55 inchloroform ........................... 64 7. CD spectra of (S,R)-52, (S,R)-82 and (R,S)-81 inchloroform ........................... 65 8. CD and UV spectra of (S ,R)-PPFA and (R,.S')-MPFA in chloroform ............................ 66 9. 300 MHz 1H NMR spectrum of S6 ................ 68 10. Broad band decoupled 13C NMR spectrum of 56 ....... 69 11. Comparison of IR spectra of 56 and (R,S)-53 in 1000 cm'1-1500 cm'1 region ................ 71 12. Mass spectrum of 56 ...................... 72 13. 2D COSY spectrum of 58 .................... 78 14. Possible structure of 65 .................... 79 15. 300 MHle NMR spectrum of 65 ............... 81 16. Comparison of far IR spectra of 57, 64 and 65 ........ 82 XII LIST OF FIGURES FIGURE PAGE 1. 300 MHz 1HNMRspectrum of 38 ................ 50 2. 300 MHz 1H NMR spectrum of (R,S)-52 ............ 51 3. Broad band decoupled 13C NMR spectrum of 37 ....... 5 8 4. DEPT 13C NMR spectrum of 37 ................. 59 5. Mid IR spectrum of compound (S,R)-50 ............ 62 6. CD spectra of (S,R)-51, (R,S)-54 and (R,S)-55 in chloroform ........................... 6 4 7. CD spectra of (S,R)-52, (S,R)-82 and (R,S)-8l inchloroform ........................... 65 8. CD and UV spectra of (S,R)-PPFA and (R,S)-MPFA in chloroform ............................ 66 9. 300 MHz 1H NMR spectrum of 56 ................ 68 10. Broad band decoupled 13C NMR spectrum of 56 ....... 69 11. Comparison of IR spectra of 56 and (R,S)-53 in 1000 cm'1-1500 cm'1 region ................ 71 12. Mass spectrum of 56 ...................... 72 13. 2D COSY spectrum of 58 .................... 78 14. Possible structure of 65 .................... 79 15. 300 MHle NMR spectrum of 65 ............... 81 16. Comparison of far IR spectra of 57, 64 and 65 ........ 82 XII 17. 18. 19. 20. 21 . 22. 23 . 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. FAB mass spectrum of 58 ................... 85 Comparsion of isotope patterns at the molecular ion region above: simulation, bottom: detected. . . . . . . . 86 Phenylacetylene + (R ,S)-68, (a)5min (b) 30 min (c) l h ................... 105 1H NMR spectra of (R)- and (S )-methy1phenyl butyrate in the presence of chiral shift reagent Eu(dcm)3 ....... 125 300 MHz 1H NMR spectrum of 37 ............... 128 Off-resonance decoupled 13C NMR spectrum of 37 ...... 129 Broad band decoupled 13C NMR spectrum of 38 ....... 130 300 MHle NMR spectrum of 39 ............... 131 Broad band decoupled 13C NMR spectrum of 39 ....... 132 300 MHz 1H NMR spectrum of 40 ............... 133 Broad band decoupled 13C NMR spectrum of 40 ....... 134 300 MHle NMR spectrum of 41 ............... 135 Broad band decoupled 13C NMR spectrum of 41 ....... 136 DEPT 13C NMR spectrum of 41 ................. 137 300 MHz 1H NMR spectrum of 42 ............... 138 Broad band decoupled 13C NMR spectrum of 42 ....... 139 300 MHz 1H NMR spectrum of 43 ............... 140 Broad band decoupled 13C NMR spectrum of 43 ....... 141 300 MHz 1H NMR spectrum of 44 ............... 142 Broad band decoupled 13C NMR spectrum of .44 ....... 143 XIII 37. 38 39 4Q 4L 48 48 44 45 46 47 48 49 58 SL 52 58 54 55 56 51 58 300 MHz 1H NMR spectrum of 45 ............... 144 Broad band decoupled 13C NMR spectrum of 45 ....... 145 300 MHz 1H NMR spectrum of 46 ............... 146 Broad band decoupled 13C NMR spectrum of 46 ....... 147 300 MHz 1H NMR spectrum of (S,R)-50 ............ 148 Broad band decoupled 13C NMR spectrum of (S,R)-50 . . . . 149 300 MHz 1H NMR spectrum of (S,R)-51 ............ 150 Broad band decoupled 13C NMR spectrum of (S,R)-51 . . . . 151 Broad band decoupled 13C NMR spectrum of (R,S)-52. . . . 152 300 MHz 1H NMR spectrum of (R,S)-53 ............ 153 Broad band decoupled 13C NMR spectrum of (R,S)-53 . . . . 154 300 MHz 1H NMR spectrum of (R,S)-54 ............ 155 Broad band decoupled 13C NMR spectrum of (R,S)-54 . . . . 156 300 MHz 1H NMR spectrum of (R,S)-55 ............ 157 Broad band decoupled 13C NMR spectrum of (R,S)-55 . . . . 158 300 MHz 1H NMR spectrum of 57 ............... 159 300 MHz 1H NMR spectrum 300 MHz 1H NMR spectrum 300 MHz 1H NMR spectrum 300 MHz 1H NMR spectrum 300 MHz 1H NMR spectrum 300 MHz 1H NMR spectrum of58 ............... 160 of60 ............... 161 of6l ............... 162 of62 ............... 163 of63 ............... 164 of 64 ............... 165 NW 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 300 MHz 1H NMR spectrum of (S,R)-66 ............ 166 300 MHz 1H NMR spectrum of (S,R)-67 ............ 167 300 MHz 1H NMR spectrum of (R,S)-68 ............ 168 300 MHz 1H NMR spectrum of (R,S)-69 ............ 169 300 MHz 1H NMR spectrum of (R,S)-70 ............ 170 300 MHz 1H NMR spectrum of (R,S)-7l ............ 171 FAB Mass spectrum of complex 57 ............... 172 FAB Mass spectrum of complex 59 ............... 173 FAB Mass spectrum of complex 65 ............... 174 FAB Mass spectrum of complex (R ,S)-68 ........... 175 XV APPLICATIONS OF FERROCENYLSULFIDE-BASED CATALYSTS IN SELECTIVE HYDROGENATIONS AND ASYMMETRIC CROSS-COUPLIN G REACTIONS INTRODUCTION The preparation of enantiomerically pure compounds is of importance to chemists since for many pharmaceuticals, food additives, fragrances and agrochemicals, the desired biological properties are strongly related to a given absolute configuration. In many cases, the undesired enantiomer can provide side effects to the drug.1 The preparation of enantiomerically pure compounds can be divided into two categories: (1). resolution of a racemic mixture (2). asymmetric syntheses, which include stoichiometric- and catalytic asymmetric synthesis Resolution is the oldest method and it has some disadvantage since the desired enantiomer cannot be obtained in more than 50% yield. However, it remains very useful if recycling of the undesired enantiomer and the resolving agent is possible. On the other hand, asymmetric synthesis makes possible preparation of a pure enantiomer from a prochiral starting material; 100% yield with respect to the starting material can often be achieved. Furthermore, by using a chiral catalyst, the efficiency can be increased dramatically since ideally only one molecule is required to carry out the reaction. This makes asymmetric catalysis very attractive because the required amount of chiral auxiliaries will be drastically decreased when compared to classical resolution process or to stoichiometric asymmetric synthesis. 2 The syntheses and applications of chiral catalysts in asymmetric syntheses have been of intense interest and activity. Spectacular progress has been made in the field of asymmetric catalysis by using homogeneous catalysts based on transition metal complexes modified by chiral ligands.2'9 To date, the choice of ligands has been mainly empirical and all attempts to find relationships between ligand structure and extent of asymmetric induction obtainable in catalytic reactions have failed. However, several requirements have been found for efficient asymmetric catalysis. They are: a. Asymmetric catalysis could be accomplished in practical, optical yields by using metal complexes of phosphines chiral at the phosphorus or carbon center. b. Best results are obtained when the catalytic complex is more stereorigid. Thus, bidentate ligands, especially if conformationally restricted, are generally most desirable. c. The best substrates are those with one or preferably more highly polar functional groups. Unfunctionallized alkanes give poor optical yields. Many transition-metal complexes attached to the chiral chelating diphosphines have shown catalytic activities.2'9 However, their stereodifferentiating ability can suffer due to their liability as complexing agents. For efficient transfer of asymmetry to a substrate to occur, the chiral ligand must be bound to the metal during the stereodifferentiating step. The n5-cyclopentadienyl unit is therefore adopted because it bonds very strongly to transition metals. Moreover, it must be possible to modify the chiral ligands so that optimal catalyst-substrate matches can be achieved. Chiral ferrocenyl ligands with both planar and center chirality are of particular interest since they are able to fulfil these requirements. The discovery of ferrocene in 195110 has led to a period of great endeavor in this field due to it’s remarkable stability and 3 unusual reactivity. Since it behaves as an aromatic system“, it readily undergoes a variety of aromatic substitution reactions such as acylation, alkylation, formylation, mercuration and sulfonation.11o12 In many ways, the chemistry of ferrocene derivatives is very similar to that of benzene derivatives; however, important differences between them arise when the stereochemistry is considered. Unlike the benzenoid aromatic compounds, ferrocene derivatives possess planar chirality if one ring carries two different substituents.13 Optical activity arises because there is no 8,, axis.14.15 Furthermore, the central element of chirality can be assessed by introducing a chiral center into the substituents. Thus, both planar and central chirality can be manifested in disubstituted ferrocenes. Starting from [dimethylaminomethyl]ferrocene l and [1-(dimethylamino)ethyl] ferrocene 6, a large number of 1,2-disubstituted ferrocenyl derivatives has been prepared by lithiation of l and 6 followed by treatment with various electrophiles. (Scheme 1) The chiral starting material 6 was first synthesized and resolved by Gokel and Ugi.15 It was lithiated with n-butyllithium stereoselectively as shown in Eq.1. H MB Li H, M9 ’02 ‘02 ‘ct @’ We: a 5... @ we: r BUU I U 0 Fe > Fe + Fe (Ea-1) Q £9 £9 (R)—6 (FI, F?)-7 (R, S)-7 96% 4% Scheme 2 shows a variety of products derived from the achiral lithiated product 2. However, these derivatives possess no optical activities. 4 Numerous stereoisomers of 8 and 10 have been prepared17'33 by the method shown in Scheme 1. Examples of the synthesis of these ferrocenyl compounds are depicted in Scheme 3. These ligands have been used extensively to prepare transition metal complexes found to be useful catalysts for asymmetric hydrogenation of olefins3234 and ketones35, asymmetric hydrosilation of ketones35, allylic alkylation37, allylic amination33, aldol condensation”. and asymmetric Grignard cross-coupling reactions“). gm“: BuLl ; © 52,0 1 H'Q’M. @ NMe, BuLI __ Fe E110 7 © R-O Fe U n-Buu TMEDA DIDCIIODI'IIIB FeR R (R ,8 )-10 Scheme 2 M H /M9 H.q/ O H. /MD NMez Ll Fe Sn M93 < CISI’IMea F9 8292 F9 SR 23 (R .R )-7 21 1) n-BuLi n-BuLI CIZPPh TMEDA 2) cum2 H M9 .0: H [Ma @ NM92 Fe )ZPPh @ NMe2 © Fe PR2 PR 24 ’- 22 Scheme 3 Asymmetric Hydrogenation The first asymmetric hydrogenation by homogeneous transition-metal catalysts were reported by Knowles and Homer and their co-workers in 1968.41~42 They used methylphenylpropyl- phosphine as a chiral ligand with a rhodium catalyst and got 4-15% optical yields in asymmetric hydrogenation of prochiral olefins.41 Since then, over 100 different ligands have been developed to obtain higher optical yields, mostly in rhodium-catalyzed asymmetric hydrogenations, and some phosphine ligands have been found very effective for hydrogenation of a-(acylamino) acrylic acids, producing a-amino acids of over 90% ee.43-44 The high stereoselectivity attained has been shown to result from the characteristic structure of the olefin substrates as well as the chiral phosphine ligands.45 Substrates that can be hydrogenated with high stereoselectivity have the following structural features: //0 Fl' x—c —— y x = NH, 0, CH2 Y = R, on H R' The substrate contains a carbonyl group three atoms removed from the double bond. This carbonyl group can coordinate with the rhodium, as well as the double bond, forming a chelated metal- substrate adduct in the diastereomeric transition states.46 Thus, the stereoselectivity can be enhanced by making the diastereomeric transition state rigid. Landis and Halpern have studied this hydrogenation both mechanistically and kinetically.47 The metal-substrate adduct has been intercepted and characterized by multinuclear NMR and X-ray crystallography“.49 The proposed catalytic mechanism is given in the following scheme. Agrrcoocn3 t NHCOCH, /p25 Rh's ’ Rh'o §técoocn, . L _ 1“ NHCOCH3 k2 21:: + - - + 1 CH2”, H Ph — H—c—coocn, k -| I 3 m Rh' SO/\ NH ‘— / [Ian 0 0 001-13 . H NH °‘( 28 " 27 ' Scheme 4 Chiral ferrocenyl phosphine-based rhodium catalysts have been reported to catalyze the hydrogenation of trisubstituted acrylicacids with up to 98.4% ee.32 Yet, to date, few asymmetric hydrogenations with sulfur-based catalysts have been reported.50 It is of great interest to investigate this hydrogenation with similar chiral ferrocenylsulfide ligands. 10 Homogeneous Selective Hydrogenation Organic substrate hydrogenation reactions, especially those involving olefins, have been thoroughly studied.113'123 A large number of transition-metal complexes has been found to serve as “precatalyst” or “catalyst precursor” for catalytic hydrogenations. Though heterogeneous catalysts are usually more convenient for practical applications, homogeneous catalytic systems have been studied in a greater detail because: (a) A homogeneous system is more substrate selective than a heterogeneous system. Examples include exceptionally efficient asymmetric hydrogenation of prochiral olefins. This selectivity is the major advantage of a soluble catalyst. (b) Homogeneous systems usually perform at higher activities. (0) The catalysts can be modified easily. (d) Kinetic and mechanistic studies can be carried out more easily. On the other hand, the major disadvantages of homogeneous hydrogenation catalysts are: (a) their sensitivity to impurities (particularly traces of oxygen), (b) their tendency to cause olefin rearrangements, (c) the difficulty encountered in separating the product from the catalysts, and (d) the catalysts can seldom be recovered after reactions are complete. The first example of homogeneous catalytic hydrogenation dates from 1938 by Calvin, who studied the reduction of benzoquinone by dissolved hydrogen.51v52 However, it was not until the discovery of the effective “Wilkinson complex”-RhCl(PPh3)33' 53 that the field of homogeneous catalysis really developed. A large number of similar transition metal complexes has been found to have high activity as well as excellent regio- or enantioselectivity. Examples include RuC12(PPh3)354, RhH(CO)(PPH3)355, IrCl(CO)(PPh3)255, and [Co(CN)5]3'. 57 Besides these mononuclear transition-metal complexes, bimetallic catalysts and metal clusters such as (7:5-C5H5)2M02(CO)458 and Ni4(u3-n2-RCECR)3 (CNR)4 59 have been used in selective homogeneous hydrogenations. 11 Recently in our laboratory, palladium ferrocenylamine sulfide catalysts have been applied in the selective hydrogenation of a variety of conjugated double bond systems with great success.124v125 Asymmetric Grignard Cross-coupling Reactions Carbon-carbon bond formation is of great importance in organic synthesis. The use of chiral transition metal catalysts for carbon- carbon bond formation is a most promising strategy, possessing the intrinsic advantages of catalytic asymmetric synthesis. An Asymmetric Grignard cross-coupling reaction was first described by Tamao and Kumada (1972) who used secondary alkyl Grignard reagents with organic halides catalyzed by nickel or palladium complexes.68 The catalytic cycle proposed consists of a sequence of steps involving a diorganometal complex as an intermediate.‘59v7O (Scheme 5) In this scheme L* is an optically active reagent that can bring about kinetic resolution of the Grignard reagent to form an optical active product.(Eq. 2) R'-X‘ R-Fl' L M /R \_/ = /X' n’ < Ln’M \R' / \ \R' Mg x x' R-ng Scheme 5 9' Fast 8' R‘ \ / 4 R2 ”)C - M98! BIMQ- C‘Wu R2 A» 92 '\:C —R‘ (Eq. 2) R3 n3 [MI-'1 R35 12 The coupling reaction of (1-phenylethyl)magnesium chloride with vinyl bromide is, by far, the most extensively studied.16’71(Eq. 3) M l L. CH3\ e .,.C—MQCI + CH2=CHBI > C Ph“. Ph/ \ 2 9 3 o A diastereomeric transition state involving coordination of magnesium to a nitrogen atom was proposed for this reaction, as exemplified by 31. It has been suggested that the amino group on the phosphine ligand is the first requisite for high stereoselectivity and that the surroundings of the nitrogen atom exert a strong effect on the stereoselectivity.72 13 Organometallics other than Mg have been employed as Grignard reagents and in some cases give better optical yields. Examples such as U“, A174, B75, Sn75, Zr77, Zn73, Hg79, etc. Eq. 4 exemplify these applications. M R—M + R1—-X L" = Fl—R1 + mX (Eq. 4) M = Ni , Pd m = M9, LI, AI, B. S": Zr, znr Hg R1 = aryl, alkyl X= 0:, Br, I, on, SH, 898, omoxomz By modifying the alkyl group in the Grignard reagent with silyl groups, optical yield up to 95 % was obtained for the reaction of a-(trimethylsilyl)benzyl magnesium chloride with allylbromides.80 (EQ- 5) H Meask Perot2 [(R.S)-PPFA] M9351». / R = H, 95 ‘70 99 R 8 M6. 85 0/0 93 R = Ph, 95 °/o so The allylsilanes are useful intermediates in organic synthesis, capable of reacting with a wide range of electrophiles in a regiospecific manner.81 They can be used for the SE' reactions to 14 produce various kinds of optically active compounds by an asymmetric induction provided by these optically active silanes.80 An alternative route to the preparation of the optically active products was described by Brubaker and co-workers by treating (l-chloroethyl)benzene with allylmagnesium chloride under the influence of chiral ferrocenylamine sulfide catalysts.”126 (Eq. 6) CH3 M / L. CH3 9 tc—X + /\/Mgc' : ,\°\/\ (Eq. 6) Pt?“ P" Optical yields obtained by this method were lower than those obtained by the previous method. (Eq. 3) The catalysts used were the air-stable ferrocenylamine sulfides of group 10 metal halides. The optical yield was found to be dependant on the environment of sulfur atom with more sterically encumbered ligands giving higher ee. Platinum and in situ nickel. complexes gave better stereoselectivity than their palladium analogues.126 As an extension of this work, we wish to investigate the influence of the amino substituents on this cross—coupling reaction. The goal of this work was to modify the amino substituent on the ferrocenylamine thioether ligands; to prepare their palladium complexes and to test their catalytic activities as well as selectivities on hydrogenations of conjugated-dienes and phenylacetylenes. Their efficiencies were compared with those of other ferrocenylthioether complexes prepared previously in this laboratory.32o33 The applications of the in situ prepared rhodium catalysts in asymmetric hydrogenation of prochiral aminoacids as well as the palladium catalysts in asymmetric Grignard cross-coupling of 1- chloroethylbenzene with allylmagnesium chloride were also investigated. EXPERIMENTAL Air-sensitive reagents were manipulated in a prepurified argon or nitrogen atmosphere by using standard Schlenk-ware techniques. All solvents were reagent grade and were distilled by standard methods.84 Dimethylaminomethylferrocene, dialkyl disulfides and dialkylamines were purchased from Aldrich Chemical Company and used as received. (R)- and (S)-N,N-Dimethyl-l-ferrocenylethylamine was prepared and resolved by Ugi’s procedure.16 1- Dimethylaminomethyl-2-a1kylthioferrocene (34,35) , (R,S)-l-(l- dimethylaminoethyl)-2-alkylthioferrocene ((R,S)-48,(R,S)-49) and (S,R)-1-(l-dimethylaminoethyl)-2-alkylthioferrocene ((S,R)-47) were prepared according to a reported procedure.85 Hydrogenation substrates were obtained from Aldrich Chemical Co., Alfa Products Co., Columbian Organic Chemical Co. or Columbian Carbon Co. and were purified by standard methods before use. The Grignard Cross-Coupling reagents, l-phenylethylchloride and allylmagnesium chloride, were purchased from Aldrich Chemical Co.. The 1H chiral shift reagent, Tris(d,d-dicampholylmethanato) europium(III) [Eu(dcm)3] was purchased from Alfa Products. 1H and 13C NMR spectra in either chloroform-d1 or acetone-d6 were obtained by use of a Varian Gemini-300 spectrometer. 2D COSY spectra were obtained by using a Varian 500 MHz spectrometer. IR spectra were recorded by means of a Nicolet 740 FTIR spectrometer by using neat films between KBr plates for liquid samples and CsI pellets for solid samples. Mass spectra were obtained by use of a Finnigan 4000 instrument with an Incos data system at 70 eV. FAB mass spectra were obtained by using a Jeol JMS-HXIIO Mass Spectrometer in a 3-Nitrobenzyl alcohol (NBA) matrix. Circular Dichroism measurements were obtained by a Jasco J-600 CD spectropolarimeter in a 1 cm cell by using CHCl3 as solvent. Optical rotation measurement was performed on a Perkin Elmer 141 polarimeter. Melting points were determined by a Thomas-Hoover 15 16 capillary apparatus and are uncorrected. Gas chromatography was carried out by using a Hewlett-Packard 5880A instrument with a 25m GB-l capillary column. Elemental analyses were performed by Galbraith Laboratories Inc. Knoxville, TN. A. Preparation of ligands a. Achiral ligands (l). 1—Diethylaminomethyl-2-methylthioferrocene (37, R=Et, R'=Me, R"=H) 1-Dimethylaminomethyl-2-methylthi0ferrocene (34, 6 g, 20.8 mmol) was placed in a 100-mL round-bottomed flask equipped with a stirring bar and a reflux condenser. After addition of 64 mL acetic anhydride the mixture was heated at 100 °C for 2h. After reaction was complete, excess acetic anhydride was removed under reduced pressure. The crude product was chromatographed on an alumina gel column with hexane/CH2C12 as eluent. The yield was almost quantitative. A solution of l g (3.3 mmol) methylthioferrocenyl ethylacetate 36 and 3.1 mL diethylamine in 30 mL methanol was refluxed for 7 h. The solvent was removed and ether was added. The solution was washed with brine, dried over anhydrous magnesium sulfate, and evaporated. The residue was purified by column chromatography (silica, 10:1 hexane/ether) to give 0.67 g brown oil: yield 64%. 1H NMR 8 ppm (J in Hz) : 4.26 (d,C5H3); 4.08-4.11 (m,C5H3); 4.08 (SKIP); 3.29-3.78 (dd,CH2,l3.0); 2.30-2.60 (m,aH,NEt2); 1.00 (t,BH,NEt2,7.0); 2.24 (s,SMe) 13C NMR 8 ppm : 87.4 (s,C1); 83.4 (s,C2); 72.0, 70.8, 67.1 (d,C3,C4,C5); 70.0 (s.Cp); 51.0 (t,CH2); 46.3 (t,aC,NE12); 11.7 (madman); 20.5(q,SMe) IR (Nujol, KBr) cm:1 : 3093 (ferrocene C-H stretch); 2798-2973 (alkyl C-H stretch); 1448 (ferrocene antisymmetric C-H stretch); 1173,1194 17 (ON stretch); 875 (C-H bending perpendicular to the plane of Cp ring); 534 (S-C stretch); 491 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 317 (Mt, 11); 270 (Mt-SMe, 35); 245 (Mt-NEtz, 89); 199 (Mt-SMe-NEtz, 49); 121 (M+-C5H3-SMe-CH2NEt2, 83); 56 (Fe, 100) Elemental Analysis for C16H23FeNS (Calc.) : C 60.12 (60.57); H 7.26 (7.09); N, 4.42 (4.43) (2). 1-Diethylaminomethyl-2-ethylthioferrocene (38, R=Et, R'=Et, R"=H) The procedure was the same as that for 37 except that 7.8 g l-Dimethylaminomethyl-2-ethylthi0ferrocene (25.7 mmol) was used. The product after being chromatographed on silica gel gave 0.94 g yellow oil. Yield : 34%. 1H NMR 8 ppm (J in Hz) : 4.27 (d.C5H3); 4.08-4.12 (m,C5H3); 4.06 (s,Cp): 3.22-3.78 (dd,CH2,l3.I); 2.34-2.57 (m,aH,NEt2); 0.98 (t,BH,NEtz,7.1); 2.55-2.72 (m,0tH,SEt); 1.14 (t,BH,SEt,7.4) 13C NMR 8 ppm : 88.4 (s,C1); 80.3 (s,C2); 74.1, 71.1, 67.4 (d,C3,C4,C5); 69.9 (S,Cp); 51.0 (t,CH2); 46.2 (t,aC,NEtz); 11.6 (q,BC,NE12); 30.8 (150.3131); 20.5 (q,BC,SEt) IR (Nujol, KBr) cm:1 : 3095 (ferrocene C-H stretch); 2796-2968 (alkyl C-H stretch); 1449 (ferrocene antisymmetric C-H stretch); 1175,1197 (C-N stretch); 818 (C-H bending perpendicular to the plane of Cp ring): 534 (S-C stretch); 500 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 331 (M+, 48); 270 (Mt-SEt, 34); 259 (Mt-NEtz, 44); 199 (M+-SEt-NEt2, 18); 121 (M+-C5H3-SEt-CH2NEt2, 43); 58 (100); 44 (62) Elemental Analysis for C17H25FeNS (Calc.) : C 61.76 (61.63); H 7.67 (7.60) 18 (3). 1-Diethylaminomethyl-2-(4-chlorophenyl)thioferrocene (39, R=Et, R'= 4-chlor0phenyl, R"=H) The procedure was the same as that for 37 except that 1.15 g 1-Dimethylaminomethyl-2-(4-chlorophenyl)thioferrocene (3.0 mmol) was used. The product after being chromatographed on silica gel gave yellow crystals. Mp. 91-92 0C. Yield : 20%. 1H NMR 5 ppm (J in Hz) : 430,440,445 (m,C5H3); 4.16 (s.Cp); 3.33- 3.64 (dd,CH2,13.6); 2.21-2.42 (m,aH,NEt2); 0.85 (t,BH,NEt2,7.1); 7.02- 7.12 (m,Ph) 13C NMR 8 ppm : 90.4 (s,C1); 76.6 (s,C2); 76.2, 73.0, 69.6 (d,C3,C4,C5); 70.9 (S.Cp); 51.7 (t,CH2); 47.0 (t,aC,NE12); 12.1 (q,BC,NE12); 140.7, 130.8, 129.0, 128.7 (m,Ph) IR (Nujol, KBr) cm'1 : 3096 (ferrocene C-H stretch); 2791-2963 (alkyl C-H stretch); 1455 (ferrocene antisymmetric C-H stretch); 1175,1197 (C-N stretch); 812 (C-H bending perpendicular to the plane of Cp ring); 545 (S-C stretch); 482 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 413 (M+, 18); 341 (M+-NEt2, 16); 270 (M+-SPhC1, 24); 199 (M+-SPhCl-NEt2, 20); 121 (M+-C5H3-SPhCl- CHzNEtz, 34); 85 (CH2NEt2,100) Elemental Analysis for C17H23C1FeNS (Calc.) : C 61.00 (60.98); H 5.85 (5.85) (4). 1-Diethylaminomethyl-2-(4-methylphenyl)thioferrocene (40, R=Et, R'= 4-methylphenyl, R”=H) The procedure was the same as that for 37 except that 8.0 g l-Dimethylaminomethyl-2-(4-methylphenyl)thioferrocene (21.9 mmol) was used. The product after being chromatographed on silica gel gave brown crystals. Mp. 56 0C. Yield : 41%. 1H NMR 8 ppm (J in Hz) : 4.27,4.41,4.47 (m,C5H3); 4.15 (s,Cp); 3.44- 3.66 (dd,CH2,13.7); 2.33 (q,aH,NEt2); 0.87 (t,BH,NEtz,7.1); 6.92-7.04 (dd,Ph); 2.22 (S,Ph-CH3) 19 13C NMR 8 ppm : 88.2 (s,C1); 77.4 (s,C2); 77.0, 71.5, 68.7 (d,C3,C4,C5); 70.1 (s,Cp); 50.4 (t,CH2); 46.1 (t,aC,NEt2); 11.5 (q,BC,NEt2); 136.9, 134.7, 129.2, 126.2 (m,Ph); 20.6 (q,Ph-CH3) IR (Nujol, KBr) cm‘1 : 3095 (ferrocene C-H stretch); 2802-2969 (alkyl C-H stretch); 1451 (ferrocene antisymmetric C-H stretch); 1175,1199 (C-N stretch); 819 (C-H bending perpendicular to the plane of Cp ring); 543 (S-C stretch); 484 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 393 (Mt, 28); 321 (Mt-NEtz, 32); 270 (Mt-SPhCH3, 46); 199 (M+-SPhCH3-NEt2, 62); 121 (M+-C5H3-SPhCH3- CHzNEtz, 55); 85 (CH2NEt2,28); 58 (Et2, 88); 40 (100) Elemental Analysis for C13H25FeNS (Calc.) : C 66.86 (67.17); H 7.11 (6.92) (5). 1-Di-n-propy1aminomethyl-2-methylthioferrocene (41, R=n-Pr, R'=Me, R"=H) The procedure was the same as that for 37 except that 4.0 mL di-n-propylamine was used to react with the corresponding sulfidoferrocenyl ethylacetate. The product after being chromatographed on silica gel gave a yellow oil. Yield : 23%. 1H NMR 8 ppm (J in Hz) : 4.10.4.26 (d,C5H3); 4.07 (s,Cp): 3.26-3.78 (dd,CH2,l3.2); 2.17-2.43 (m,aH,NEt2); 1.30-1.50 (m,BH,NEt2); 0.81 (t,yH,7.3); 2.24 (s,SMe) 13C NMR 8 ppm : 87.4 (s,C1); 83.3 (s,C2); 72.1, 70.9, 67.1 (d,C3,C4,C5); 69.8 (S,Cp); 55.5 (t,CH2); 52.2 (t,aC,NEtz); 20.0 (m,|3C,NEt2); 11.7 (q.1C,NEt2); 20.4 (q,SMe) IR (Nujol, KBr) cm'1 : 3095 (ferrocene C-H stretch); 2798-2958 (alkyl C-H stretch); 1457 (ferrocene antisymmetric C-H stretch); 1173,1187 (C-N stretch); 819 (C-H bending perpendicular to the plane of Cp ring); 528 (S-C stretch); 482 (antisymmetric ring-metal stretch) 20 MS m/e (relative intensity) : 345 (M+, 19); 298 (Mt-8M0, 8); 245 (M+-NPr2, 100); 199 (M+-SMe-NPr2, 13); 121 (M+-C5H3-SMe-CH2NPr2, 44); 56 (Fe, 100); 43 (C3H7, 88) Elemental Analysis for C13H27FeNS (Calc.) : C 62.21 (62.61); H 7.86 (7.88) (6). 1-Di-n-propylaminomethyl-2-ethylthi0ferrocene (42, R=n-Pr, R'=Et, R"=m The procedure was the same as that for 37 except that 1.0 g ethylthioferrocenyl ethylacetate was used. The product after being chromatographed on silica gel gave a yellow oil. Yield : 55%. 1H NMR 8 ppm (J in Hz) : 4.1l,4.28 (d,C5H3); 4.07 (s,Cp); 3.20-3.78 (dd,CH2,l3.2); 2.18-2.43 (m,aH,N-n-Pr2); 1.32-1.50 (m,BH,N-n-Pr2); 0.80 (t,yH,N-n-Pr2,7.3); 2.53-2.77 (m,aH,SEt); 1.14 (t,BH,SEt,7.4) 13C NMR 5 ppm : 88.5 (s,C1); 80.1 (s,Cz); 74.3, 71.3, 67.2 (d,C3,C4,C5); 69.8 (s,Cp); 55.6 (t,CH2); 52.5 (t,aC,NEt2); 20.0 (m,8C,NEt2); 11.7 (q,yC,NEt2); 30.9 (t,aC,SEt); 14.5 (q,BC,SEt) IR (Nujol, KBr) cm:1 : 3095 (ferrocene C-H stretch); 2798-2958 (alkyl C-H stretch); 1456 (ferrocene antisymmetric C-H stretch); 1172,1187 (C-N stretch); 819 (C-H bending perpendicular to the plane of Cp ring); 522 (S-C stretch); 478 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 359 (Mt, 43); 298 (M+-SEt, 29); 259 (M+-N-n-Pr2, 100); 199 (M+-SEt-N-n-Pr2, 13); 105 (14); 72 (53) Elemental Analysis for C19H29FeNS (Calc.) : C 62.83 (63.50); H 8.07 (8.07) (7). 1-Di-i-propylamin0methyl-2-ethylthioferrocene (43, R=i-Pr, R'=Et,R"=H) The procedure was the same as that for 37 except that 4.2 mL isopropylamine was used. The product after being chromatographed on silica gel gave a yellow oil. Yield : 52%. 21 1H NMR 8 ppm (J in Hz) : 4.08,4.28 (d,C5H3); 4.08 (s,Cp); 3.38-3.74 (dd,CH2,13.5); 3.02 (m,aH,N-i-Pr2); 1.00 (dd,BH,N-i-Pr2,4.8); 2.50-2.73 (m,aH,SEt); 1.13 (t,BH,SEt,6.9) 13C NMR 8 ppm : 90.7 (s,Cl): 79.4 (s,Cz): 74.3, 71.5, 66.8 (d,C3,C4,C5); 69.8 (s,Cp); 42.5 (t,CH2); 46.6 (t,aC,N-i-Pr2): 21.1,19.9 (m,BC,N-i-Pr2); 31.0 (t,aC,SEt); 14.6 (q,BC,SEt) IR (Nujol, KBr) cm'1 : 3095 (ferrocene C-H stretch); 2813-2964 (alkyl CH stretch); 1457 (ferrocene antisymmetric CH stretch); 1179,1200 (C-N stretch); 818 (C-H bending perpendicular to the plane of Cp ring); 533 (S-C stretch); 489 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 359 (Mt, 6); 298 (Mt-SEt, 4); 259 (Mt- N-i-Prz, 47); 121 (Mt-SEt-CHzN-i-Pr2-C5H3, 26); 86 (N-i-Pr2,44); 44 (100) Elemental Analysis for C19H29FeNS (Calc.) : C 63.18 (63.50); H 8.07 (8.07) (8). 1-Di-i-butylaminomethyl~2—ethylthioferrocene (44, R=i-Bu, R'=Et, R"=H) The procedure was the same as that for 37 except that 5.2 mL isobutylamine was used. The product after being chromatographed on silica gel gave a brown oil. Yield : 25%. 1H NMR 8 ppm (J in Hz) : 4.11,4.29 (d,C5H3); 4.06 (s,Cp); 3.17-3.69 (dd,CH2,13.2); 1.93-2.14 (m,aH,N-i-Bu2);1.71 (m,BH,N-i-Buz); 0.78- 0.84 (dd,yH,N-i-Bu2,6.5); 2.50-2.73 (m,aH,SEt); 1.15 (t,BH,SEt,7.4) 13C NMR 8 ppm : 88.2 (s,Cr); 80.0 (s,C2); 74.2, 71.5, 67.3 (d,C3,C4,C5); 69.8 (s,Cp); 53.5 (00-12); 30.9 (t,aC,N-i-Bu2); 26.2 (m,8C,N-i-Bu2); 20.8,20.7(q,yC,N-i-Bu2); 36.6 (t,aC,SEt); 26.2 (11.50.3151) IR (Nujol, KBr) cm'1 : 3096 (ferrocene C-H stretch); 2795-2954 (alkyl C-H stretch); 1458 (ferrocene antisymmetric CH stretch); 1171,1195 (C-N stretch); 820 (C-H bending perpendicular to the plane of Cp ring); 531 (S-C stretch); 492 (antisymmetric ring-metal stretch) 22 MS m/e (relative intensity) : 387 (Mt, 7); 326 (Mt-SEt, l); 259 (M+- CHzN-i-Buz, 100); 121 (M+-SEt-CH2N-i-Buz-C5H3, 35); 56 (Fe,38); 41 (93) Elemental Analysis for C21H33FeNS (Calc.) : C 63.91 (65.11); H 8.31 (8.52) (9). l-Dipheny1aminomethyl-2-p-chlorophenylthioferrocene (45, R=Ph, R'= p-chlorophenyl, R"=H) The procedure was the same as that for 37 except that 1.0 g 1-Dimethylaminomethyl-Z-(4-chlorophenyl)thioferrocene (21.9 mmol) and 0.5 g diphenylamine was used. The product after being chromatographed on silica gel gave brown crystals. Mp. 118 oC. Yield : 22%. 1H NMR 5 ppm (J in Hz) : 4.32,4.43,4.46 (61.05113); 4.06 (s,Cp); 4.54- 5.09 (dd,CH2,l6.7); 6.87-6.93 (t,NPh2); 6.94-6.99 (d,NPh2,PllCl); 7.06- 7.11 (d,PhCl); 7.06-7.12 (1.51141) 130 NMR 5 ppm : 90.2 (s,C1); 74.5 (s,Cz); 75.7, 72.3, 69.5 (d,C3,C4,C5); 71.3 (s,Cp); 51.3 (1.0112): 149, 130.1, 122.3, 122.1 (m,NPh2); 140.1, 131.1, 129.6, 128.1 (m,Ph-Cl) 1R (Nujol, KBr) cm'1 : 3017 (ferrocene C-H stretch); 1476,1497 (ferrocene antisymmetric CH stretch); 1217,1256 (C-N stretch); 754 (C-H bending perpendicular to the plane of Cp ring); 698,670 (S-C stretch); 482 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 509 (Mt, 53); 341 (M+-NPh2, 100); 306 (M+-NPh2-Cl, 10), 275 (M+-NPh2-Ph, 11); 249 (184 + C5H5, 14), 184 (Mt-CHzNPh-SPhCl, 8); 121 (Fe+ C5H5, 8) (10). l-methylethylamin0methyl-2-methylthioferrocene (46, R=NMeEt, R'= Me, R"=H) To 1 g (3.3 mmol) of 36 was added, via syringe, 20 mL 1.0 M HCl in diethylether at 0 °C.147 The solution was allowed to warm to room temperature and stirred for a further 3h. The solvent was 23 removed by evacuation and a fresh 20 mL portion of dried ether was added to the residue. To this solution was added, via syringe, a mixture of 2.5 mL Methylethylamine in 20 mL ether at 0 °C. After being stirred for 3h, 10 mL of saturated aqueous NaHCO3 was added. The resulting organic layer and ether extracts from the aqueous layer were combined, washed, dried and evaporated. The product was purified by column chromatography to give 0.22 g (65% overall yield) 1-methylethylaminomethyl-2-methylthioferrocene. 1H NMR 8 ppm (J in Hz) : 4.29 (d,2H,C5H3); 4.13 (m,1H,C5H3); 4.08 (s,Cp); 3.26-3.70 (dd,CH2,12.9); 2.40 (dq,aH,NEt,7.2); 1.06 (t,|3H,NEt,7.2); 2.15 (s, NMe); 2.24 (s,SMe) 13C NMR 8 ppm : 86.2 (s,Cl); 83.7 (s,Cz); 71.8, 70.6, 67.4 (d,C3,C4,C5); 69.9 (S,Cp); 55.0 (t,CH2); 51.0 (t,aC,NEt); 12.6 (q,Bc,NEt); 41.2 (q,NMe); 20.3(q,SMe) IR (Nujol, KBr) cm“1 : 3084 (ferrocene C-H stretch); 2781-2971 (alkyl C-H stretch); 1450 (ferrocene antisymmetric C-H stretch); 1175,1190 (C-N stretch); 809 (CH bending perpendicular to the plane of Cp ring); 527 (S-C stretch); 492 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 317 (M+, 11); 270 (M+-SMe, 35); 245 (M+-NEt2, 89); 199 (M+-SMe-NEt2, 49); 121 (M+-C5H3-SMe-CH2NEt2, 83); 56 (Fe, 100) 24 b. Chiral ligands (l). (S,R)-1-(1-Diethylaminoethyl)-2-methylthioferrocene ((S,R)- 50,R=Et, R’=Me, R”=Me) To 1.96 g (S,R)-l-(1-Dimethylaminoethyl)-2-methylthio ferrocene (6.47 mmol) was added 4.04 mL acetic anhydride; the mixture was heated at 50 0C for 2h. Excess acetic anhydride was removed under reduced pressure. The crude product was chromatographed on a silica gel column with hexane/CH2C12 as eluent to give 1.710 g (83.1% yield) methylthioferrocenyl ethylacetate. A solution of 0.93 g (2.0 mmol) methylthioferrocenyl ethylacetate in 2.5 mL methanol was added to 3.03 mL HNEtz and then stirred at room temperature for 24 h. The work up procedure was similar to that for the achiral ligands. The residue was purified by chromatography on a silica gel to give 0.44 g brown oil. Yield : 82%. 1H NMR 8 ppm (J in Hz) : 4.27,4.21,4.11 (m,C5H3); 4.07 (s,Cp); 4.25 (q,CH—CH3,6.8); 1.27 (d,CIi3-CH,6.7); 2.22-2.54 (m,aH,NEt2); 1.00 (t,BH,NEt2,7.1); 2.29 (s,SMe) 13C NMR 8 ppm : 94.2 (s,Cl); 82.3 (s,Cz); 72.3, 68.0, 66.3 (d,C3,C4,C5); 69.8 (s,Cp); 52.5 (d,C_H-CH3); 10.8 (q,CH-QH3); 43.2 (t,aC,NE12); 14.2 (q.BC.NEt2); 20.6 (q,SMe) IR (Nujol, KBr) cm:1 : 3095 (ferrocene C-H stretch); 2808-2970 (alkyl C-H stretch); 1449 (ferrocene antisymmetric C-H stretch); 1176,1199 (C-N stretch); 818 (C-H bending perpendicular to the plane of Cp ring); 543 (S-C stretch); 509 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 331 (Mt, 8); 258 (Mt-NEtz, 66); 243 (M+-Me-NEt2, 31); 121 (Mt-C5H3-SMe-CHCH3NEt2, 72); 58 (Etz, 100); 56 (Fe, 54) Elemental Analysis for C17H25FeNS (Calc.) : C 61.49 (61.63); H 7.46 (7.60) 25 (2). (S ,R)-1 -( l -Di-n-pr0pylamin0ethyl)-2-ethylthioferrocene ( (S ,R ) - 51, R=n-Pr, R’=Et, R”=Me) The procedure was the same as that for (S,R)-50 except that 4.0 mL Di-n-propylamine was used. The product after being chromatographed on silica gel gave a brown oil. Yield : 53%. 1H NMR 8 ppm (J in Hz) : 4.26,4.20,4.10 (m,C5H3); 4.06 (s,Cp); 4.16 (q,CH—CH3); 1.27 (d,CH3-CH,6.8); 2.18-2.38 (m,aH,N-n-Pr2); 1.20-1.52 (m,BH,N-n-Pr2,7.1); 0.73 (t,yH,N-n-Pr2,7.1); 2.28 (s,SMe) 13C NMR 8 ppm : 94.1 (s,Cl); 82.7 (s,Cz); 71.6, 67.9, 66.3 (d,C3,C4,C5); 69.8 (S,Cp); 53.2 (d,§H-CH3); 11.8 (q,CH-C_H3); 52.5 (t,aC,N-n-Pr2)3 22.2 (t,BC,N-n-Pr2); 10.8 (q,yC,N-n-Pr2); 20.3 (q,SMe) IR (Nujol, KBr) cm'1 : 3095 (ferrocene C-H stretch); 2808-2958 (alkyl CH stretch); 1456 (ferrocene antisymmetric C-H stretch); 1174,1185 (C-N stretch); 818 (C-H bending perpendicular to the plane of Cp ring): 521 (S-C stretch); 512 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 359 (M+, 2); 258 (M+-N-n-Pr2, 100); 243 (M+-Me—N-n-Pr2, 50); 121 (M+-C5H3-SMe-CHCH3N-n-Pr2, 69); 72 (86); 56 (Fe, 48); 43(C3H7, 50) Elemental Analysis for C19H29FeNS (Calc.) : C 62.85 (63.50); H 7.98 (8.07) (3). (R ,S)-1-(1 -Diethylaminoethyl)-2-ethylthioferrocene ((R ,S)-52, R=Et, R’=Et, R”=Me) The procedure was the same as that for (S ,R)-50 except that (R,S)-l-(1-Dimethylaminoethyl)-2-ethylthioferrocene (6.47 mmol) was used. The product after being chromatographed on silica gel gave a brown oil. Yield : 64% 1H NMR 8 ppm (J in Hz) : 4.30.4.21,4.14 (m,C5H3); 4.07 (s,Cp); 4.24 (q,CH-CH3,7.0); 1.26 (d,Cfl3-CH,6.1); 2.26,2.47 (m,aH,NEt2); 0.92 (t,BH,NE12,7.1); 2.60.2.90 (m,0tH,SEt); 1.13 (t,BH,SEt,7.5) 26 13C NMR 8 ppm : 96.0 (s,Cl); 77.6 (s,Cz); 76.1, 68.4, 66.6 (d,C3,C4,C5); 69.9 (s,Cp); 52.3 (d,C_H-CH3); 10.2 (q,CH-C_H3); 43.2 (t,aC,NEt2); 14.3 (q,BC,NEt2); 30.6 (t,aC,SEt); 14.3 (q,BC,SEt) IR (Nujol, KBr) cm-1 : 3095 (ferrocene C-H istretch); 2806-2970 (alkyl C-H stretch); 1449 (ferrocene antisymmetric C-H stretch); 1175,1198 (C-N stretch); 819 (C-H bending perpendicular to the plane of Cp ring); 542 (S-C stretch); 509 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 345 (Mt, 6); 272 (Mt-NEtz, 30); 243 (Mt-Me-NEtz, 29); 121 (M+-C5H3-SMe-CHCH3NEt2, 68); 58 (E12, 100); 56 (Fe, 47) Elemental Analysis for C13H27FeNS (Calc.) : C 62.59 (62.61); H 7.98 (7.88) (4). (R ,S )-l -(1-Di-n-pr0pylaminoethyl)-2-ethylthioferrocene ((R,S)- 53, R=n-Pr, R’=Et, R”=Me) The procedure was the same as that for (R,S)-52 except that 4.0 mL Di-n-propylamine was used. The product after being chromatographed on silica gel gave a brown oil. Yield : 16%. 1H NMR 8 ppm (J in Hz) : 4.29,4.19,4.12 (m,C5H3); 4.06 (s,Cp); 4.15 (q,Cfl-CH3); 1.26 (d,Cflq-CH,6.8); 2.13-2.38 (m,orH,N-n-Pr2); 1.21,1.40 (m,BH,N-n-Pr2,7.1); 0.72 (t,yH,N-n-Pr2,7.3); 2.60,2.83 (m,aH,SEt); 1.13 (t,BH,SEt,7.4) 130 NMR 5 ppm : 95.1 (s,Cl); 78.9 (s,Cz): 74.6, 68.3, 66.6 (d,C3,C4,C5); 69.9 (s,Cp); 53.1 (d,c_H-CH3); 11.7 (q,CH-QH3): 52.6 (t,01C,N-n-Pr2): 22.3 (t,BC,N-n-Pr2); 10.5 (q,yC,N-n-Pr2); 30.7 (t,aC,SEt); 14.4 (q,BC,SEt) IR (Nujol, KBr) cm“1 : 3098 (ferrocene C-H stretch); 2809-2961 (alkyl C-H stretch); 1456 (ferrocene antisymmetric C-H stretch); 1173,1185 (C-N stretch); 820 (C-H bending perpendicular to the plane of Cp ring); 543 (S-C stretch); 505 (antisymmetric ring-metal stretch) 27 MS m/e (relative intensity) : 373 (M+, 2); 272 (Mt-N-n-Prz, 40); 243 (M+-Me-N-n-Pr2, 32); 121 (M+-C5H3-SEt-CHCH3N-n-Pr2, 50); 72 (100); 56 (Fe, 33) Elemental Analysis for C20H31FeNS (Calc.) : C 63.69 (64.34); H 8.22 (8.37) (5). (R,S)-l-(1-Diethylamin0ethyl)-2-isopropylthioferrocene ((R,S)- 54, R=Et, R’=i-propyl, R”=Me) The procedure was the same as that for (R ,S )-52 except that (R,S)-1-(1-Dimethylaminoethyl)-2-isopr0pylthioferrocene (7 mmol) was used. The product after being chromatographed on silica gel gave a brown oil. Yield : 26% 1H NMR 5 ppm (J in Hz) : 4.28,4.21,4.l4 (m,C5H3); 4.06 (s,Cp); 4.24 (q,CH—CH3,6.7); 1.24 (d,CH3-CH,6.8); 2.19-2.30, 2.43-2.56 (m,aH,NEt2); 0.89 (t.8H,NE12,7.1); 3.52 (m,01H,SEt); 1.15.1.05 (d,BH,SEt,6.5) 13C NMR 8 ppm : 96.0 (s,Cl); 77.6 (s,Cz); 76.1, 68.4, 66.7 (d,C3,C4,C5); 69.9 (S.Cp); 52.2 (d,§H-CH3); 9.70 (q,CH-§H3): 43.2 (LaC,NEt2); 14.3 (q,BC,NEtz); 38.2 (d,aC,S-i-Pr); 23.2,21.7 (q,BC,S-i-Pr) 1R (Nujol, KBr) cm'1 : 3096 (ferrocene C-H stretch); 2806-2963 (alkyl C-H stretch); 1451 (ferrocene antisymmetric C-H stretch); 1154,1169 (C-N stretch); 822 (C-H bending perpendicular to the plane of Cp ring); 542 (S-C stretch); 507 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 359 (Mt, 4); 286 (M+-NEt2, 100); 243 (M+-C3H7-NEt2, 63); 121 (M+-C5H3-S-i-Pr-CH-CH3NEt2, 56); 58 (Etz, 55); 43 (C3H7, 74) Elemental Analysis for C19H29FeNS (Calc.) : C 63.67 (63.50); H 8.11 (8.07) 28 (6). (R,S)-1-(1-Di-n-propylaminoethyl)-2-isopropylthioferrocene ((R,S)-55 ,Rzn-Pr, R’= i-Pr, R”: Me) The procedure was the same as that for (R ,S )-54 except that 4.0 mL Di-n-propylamine was used. The product after being chromatographed on silica gel gave a brown oil. Yield : 30%. 1H NMR 8 ppm (J in Hz) : 4.29,4.22,4.15 (m,C5H3); 4.06 (s,Cp); 4.19 (q,CH-CH3,6.9); 1.27 (d,CI:L3-CH,6.9); 2.14-2.40 (m,aH,N-n-Pr2); 1.10- 1.49 (m,BH,N-n-Pr2,); 0.72 (t,yH,N-n-Pr2,7.4); 3.42 (m,0tH,S-i-Pr); 1.15.1.07 (d,BH,S-i-Pr,6.9) 13C NMR 8 ppm : 96.0 (s,Cl); 76.0 (s,C2); 70.6, 68.7, 66.8 (d,C3,C4,C5); 69.9 (s,Cp); 53.1 (d,QH-CH3); 11.8 (q,CH-CH3); 52.6 (t,aC,N-n-Pr2); 22.3 (t,BC,N-n-Pr2); 10.1 (q,yC,N-n-Pr2); 38.2 (d,aC,S-1’-Pr); 23.3,21.7 (q,BC,S-i-Pr) IR (Nujol, KBr) cm“1 : 3098 (ferrocene C-H stretch); 2808-2961 (alkyl CH stretch); 1453 (ferrocene antisymmetric C-H stretch); 1156,1171 (C-N stretch); 822 (C-H bending perpendicular to the plane of Cp ring); 542 (S-C stretch); 507 (antisymmetric ring-metal stretch) MS m/e (relative intensity) : 387 (M+, 2); 286 (M+-N-n-Pr2, 81); 243 (Mt-C3H7-N-n-Pr2, 57); 178 (M+-C5H5-N-n-Pr2-C3H7, 29); 121 (M+- C5H3-S-i-Pr-CH-CH3N-n-Pr2, 97); 56 (Fe, 33); 43 (C3H7, 33) Elemental Analysis for C21H33FeNS (Calc.) : C 64.62 (65.11); H 8.22 (8.52) 29 0. Synthesis of Ferrocenylsulfide Ligand 1. 1-Methylthio-2-ethylthiomethylferrocene 56. To 1 g (3.3 mmol) of 36 was added, via syringe, 20 mL 1.0 M HCl in diethylether at 0 °C.104 The solution was allowed to warm to room temperature and stirred for a further 3h. The solvent was removed by evacuation and a fresh 20 mL portion of dried ether was added to the residue. To this solution was added, via syringe, a mixture of 2.5 mL ethanethiol and 80 mg Na in 20 mL ether at 0 °C. After being stirred for 3h, 10 mL of saturated aqueous NaHCO3 was added. The resulting organic layer and ether extracts from the aqueous layer were combined, washed, dried and evaporated. The product was purified by column chromatography to give 0.85 g (84% overall yield) 1-methylthio-2-ethylthiomethylferrocene 56. 1H NMR 5 ppm (J in Hz) : 4.31,4.26,4.13 (m,C5H3); 4.10 (s,Cp); 3.53- 3.81 (dd,CH2,7.2); 2.52 (q,(1H,SEt,7.1); 1.24 (t,BH,SEt,7.2); 2.25 (s,SMe) 13C NMR 8 ppm : 88.0 (s,Cl); 81.8 (s,Cz); 72.8, 69.3, 67.4 (d,C3,C4,C5); 70.0 (S.Cp); 29.9 (t,CH2); 26.2 (t,aC,SEt); 14.6 (q,BC,SEt); 20.9(q,SMe) IR (Nujol, KBr) cm:1 : 3096 (ferrocene C-H stretch); 2820-2965 (alkyl C-H stretch); 1447 (ferrocene antisymmetric C-H stretch); 822 (C-H bending perpendicular to the plane of Cp ring); 532 (S-C stretch); 483 (antisymmetric ring-metal stretch) Elemental Analysis for C14H13FeS2 (Calc.) : C 54.77 (54.90); H 5.92 (5.92) 30 B. Preparation of palladium and platinum complexes (1). 1-Diethylaminomethyl-2-methylthioferrocenyl Palladium Chloride (57, R=Me, R’=Et, R”=H) To a benzene solution of 0.2 g (PhCN)2PdC12 was added 0.17 g 1-Diethylaminomethyl-2-methylthioferrocene. The mixture was stirred overnight and the resulting red precipitate was collected by filtration and washed with cold benzene and ether to give 0.236 g product. Pure crystals were obtained by recrystallization from CH2C12/hexane. Mp. 154-156 0C; yield : 87% (based on (PhCN)2PdC12) 1H NMR 8 ppm (J in Hz) : 4.52,4.41,4.32 (m,C5H3); 4.24 (s,Cp); 2.90.3.95 (d,CH2,13.7); 3.87,3.28,2.67,2.30 (m,aH,NEt2); 1.00,1.95 (t,BH,NEtz,7.1); 2.75 (s,SMe) IR (CsI pellet) cm-l : 3088 (ferrocene C-H stretch); 2969-2932 (alkyl C-H stretch); 1458,1408 (ferrocene antisymmetric CH stretch); 1108,1088 (C-N stretch); 833 (C-H bending perpendicular to the plane of Cp ring); 633 (S-C stretch); 494 (antisymmetric ring-metal stretch); 511 (Pd-N stretch); 322 (Pd-Cl stretch); 291 (Pd-S stretch) MS m/e (relative intensity) : 317 (M+-PdC12, 11); 270 (Mt-PdClz-SMe, 35); 245 (M+-PdC12-NEt2, 89); 199 (Mt-PdClz-SMe-NEtz, 49); 121 (M+- PdClz-C5H3-SMe-CH2NEt2, 83) Elemental Analysis for C15H23FeNSPdC12 (Calc.) : C 38.82 (38.86); H 4.67 (4.69) (2). 1-Diethylaminomethyl-2-ethylthioferrocenyl Palladium Chloride (58, R=Et, R'=Et, R"=H) The procedure was the same as that for 57 except that 0.18 g 1-Diethylaminomethyl-2-ethylthi0ferrocene was used. The product after crystallization gave 0.181 g dark red crystals. Mp. 110-112 0C; yield : 65%. 31 1H NMR 8 ppm (J in Hz) : 4.53.4.40,4.34 (m,C5H3); 4.22 (s,Cp); 4.04.2.85 (d,CH2,13.6); 3.90,3.20,2.60,2.20 (m,aH,NEt2); 1.91.1.03 (t,BH,NE12,7.1); 3.40.3.20 (m,aH,SEt); 1.70 (t,BH,SEt,7.2) IR (CsI pellet) cm'l : 3081 (ferrocene C-H stretch); 2959,2924 (alkyl C-H stretch); 1454 (ferrocene antisymmetric C-H stretch); 1223,1152 (C-N stretch); 832 (C-H bending perpendicular to the plane of Cp ring); 612 (S-C stretch); 515 (Pd-N stretch); 328 (Pd-Cl stretch); 295 (Pd-S stretch) FAB MS m/e (relative intensity) : 508 (Mt; 10); 436 (M+-Clz,l3); 331 (M+-PdC12, 52); 259 (M+-PdC12-NEt2, 73); 121 (M+-PdC12-C5H3-SEt- CHzNEtz, 60); 71 (NE12,63) Elemental Analysis for C17H25FeNSPdC12 (Calc.) : C 39.74 (40.15); H 4.83 (4.95) (3). l-Diethylaminomethyl-2-(4-0hlorophenyl)thioferrocenyl Palladium Chloride (59, R=Et, R'=4-chlorophenyl, R"=H) The procedure was the same as that for 57 except that 0.23 g 1-Diethylaminomethyl-2-(4-chlorophenyl)thioferrocene was used. The product after crystallization gave 0.194 g brick red crystals. Mp. 135 OC; yield : 60%. 1H NMR 8 ppm (J in Hz) : 4.40,4.23,4.00 (m,C5H3); 4.10 (s,Cp); 4.64,2.96 (d,CH2,13.6); 4.04,3.18,2.76,2.41 (m,aH,NEt2); 1.96,l.06 (t,BH,NEtz,7.1); 7.85.7.44 (m,Ph) IR (CsI pellet) cm:l : 3093 (ferrocene C-H stretch); 2931,2973 (alkyl C-H stretch); 1476 (ferrocene antisymmetric C-H stretch); 1096,1103 (C-N stretch); 829,808 (C-H bending perpendicular to the plane of Cp ring); 681 (S-C stretch); 491 (antisymmetric ring-metal stretch); 503 (Pd-N stretch); 329 (Pd-C1 stretch); 305 (Pd-S stretch) MS m/e (relative intensity) : 413 (Mt-PdClz, 18); 341 (M+-PdC12-NEt2, 16); 270 (M+-PdClz-SPhCl, 24); 199 (M+-PdC12-SPhCl-NEt2, 20); 121 (M+-PdC12-C5H3-SPhCl-CH2NEt2, 34); 85 (CH2NEt2,100) 32 Elemental Analysis for C17H23C1FeNSPdC12 (Calc.) : C 42.26 (42.69); H 4.02 (4.06) (4). 1-Diethylaminomethyl-Z-(4-methylpheny1)thioferrocenyl Palladium Chloride (60, R=Et, R'=4-methylphenyl, R"=H) The procedure was the same as that for 57 except that 0.22 g 1-Diethylaminomethyl-2-(4-methylphenyl)thioferrocene was used. The product after crystallization gave 0.222 g brick red crystals. Mp. 165-166 0C; yield : 71%. 1H NMR 8 ppm (J in Hz) : 4.38,4.22,4.15 (m,C5H3); 4.06 (s,Cp); 4.64.2.92 (d,CH2,13.6); 4.06-3.95,3.18,2.75 (m,aH.NEt2); 1.94.1.08 (t,BH,NE12,7.1); 7.83,7.26 (m,Ph); 2.37 (S,Ph-CH3) IR (CsI pellet) cm'l : 3086 (ferrocene C-H stretch); 2924-2959 (alkyl C-H stretch); 1490 (ferrocene antisymmetric C-H stretch); 1081,1107 (C-N stretch); 804 (C-H bending perpendicular to the plane of Cp ring); 486 (antisymmetric ring-metal stretch); 497 (Pd-N stretch); 328 (Pd-C1 stretch); 302 (Pd-S stretch) MS m/e (relative intensity) : 393 (M+-PdC12, 28); 321 (M+-PdC12-NEt2, 32); 270 (M+-PdC12-SPhCH3, 46); 199 (M+-PdClz-SPhCH3-NEt2, 62); 121 (M+-PdC12-C5H3-SPhCH3-CH2NEtz, 55); 85 (CH2NEt2,28); 58 (E12, 88); 40 (100) Elemental Analysis for C13H25FeNSPdC12 (Calc.) : C 46.72 (46.32); H 4.96 (4.77) (5). 1-Di-n-propylaminomethyl-2-methylthioferrocenyl Palladium Chloride (61, R=n-Pr, R'=Et, R"=H) The procedure was the same as that for 57 except that 0.19 g 1-Di-n-propylaminomethyl-2-methylthioferrocene was used. The product after crystallization gave 0.195 g brick red crystals. Mp. 142-144 0C; yield : 68%. 1H NMR 8 ppm (J in Hz) : 4.51,4.38,4.32 (m,C5H3); 4.22 (s,Cp); 3.95.2.95 (d,CH2,l3.6); 3.73,3.08,2.47,2.13 (dt,01H,N-n-Pr2); 33 3.21,l.98,l.65,l.37 (m,BH,N-n-Pr2,7.l); 1.05,0.68 (t,‘yH,N-n-Pr2,7.2); 2.73 (s,SMe) IR (CsI pellet) cm'l : 3093 (ferrocene CH stretch); 2924,2959 (alkyl C-H stretch); 1462 (ferrocene antisymmetric C-H stretch); 1079,1107 (C-N stretch); 831 (C-H bending perpendicular to the plane of Cp ring); 518 (Pd-N stretch); 323 (Pd-Cl stretch); 295 (Pd-S stretch) MS m/e (relative intensity) : 345 (M+-PdC12, 19); 298 (M+-PdC12-SMe, 8); 245 (M+-PdC12-NPr2, 100); 199 (M+-PdC12-SMe-NPr2, 13); 121 (M+-PdC12-C5H3-SMe-CHzNPrz, 44); 56 (Fe, 100); 43 (C3H7, 88) Elemental Analysis for C13H27FeNSPdC12 (Calc.) : C 41.79 (41.37); H 5.33 (5.17) (6). 1-Di-n-propylaminomethyl-2-methylthioferrocenyl Palladium Chloride (62, R=n-Pr, R'=Et, R"=H) The procedure was the same as that for 57 except that 0.20 g 1-Di-n-propylaminomethyl-2-methylthioferrocene was used. The product after crystallization gave 0.212 g dark red crystals. Mp. 127- 128 0C; yield : 72%. 1H NMR 8 ppm (J in Hz) : 4.53.4.34 (m,C5H3); 4.21 (s,Cp); 4.06.2.90 (d,CH2,13.7); 3.79,3.18,2.97,2.36 (dt,aH,N-n-Pr2); 2.10-1.90,1.65-1.40 (m,BH,N-n-Prz,7.1); 1.04.0.68 (t,yH,N-n-Pr2,7.4); 3.41.3.17 (m,aH,SEt); 1.69 (t.BH,SEt,7.2) IR (CsI pellet) cm:1 : 3093 (ferrocene C-H stretch); 2924,2959 (alkyl C-H stretch); 1462 (ferrocene antisymmetric C-H stretch); 1082,1103 (C-N stretch); 820 (C-H bending perpendicular to the plane of Cp ring); 682 (S-C stretch); 518 (Pd-N stretch); 325 (Pd-Cl stretch); 296 (Pd-S stretch) MS m/e (relative intensity) : 359 (M+-PdC12, 43); 298 (M+-PdC12-SEt, 29); 259 (M+-PdClz-N-n-Pr2, 100); 199 (M+-PdC12-SEt-N-n-Pr2, 13); 105 (14); 72 (53) 34 Elemental Analysis for C19H29FeNSPdC12 (Calc.) : C 42.81 (42.52); H 5.29 (5.45) (7). 1-Ethylmethylaminomethyl-2-methylthio ferrocenyl palladium chloride (63, R=NMeEt, R'=Et, R"=H) The procedure was the same as that for 57 except that 0.18 g 1-ethylmethylaminomethyl-2-ethylthioferrocene was used. The product after crystallization gave 0.181 g dark red crystals. Mp. 110- 112 0C; yield : 65%. 1H NMR 8 ppm (J in Hz) : 4.48,4.40,4.34 (m,C5H3); 4.24 (s,Cp); 4.02.2.53 (d,CH2,13.6); 3.97.2.13 (m,aH,NEt); 2.37 (s,01H,NMe) 1.90 (t,BH,NEt,7.0); 2.70 (s, SMe) IR (CsI pellet) cm'1 : 3088 (ferrocene C-H stretch); 2971,2926 (alkyl CH stretch); 1464,1414 (ferrocene antisymmetric C-H stretch); 1107 (ON stretch); 837 (CH bending perpendicular to the plane of Cp ring); 635 (S-C stretch); 513 (Pd-N stretch); 329 (Pd-Cl stretch); 295 (Pd-S stretch) MS m/e (relative intensity) : 480 (M+,5); 409 (Mt-02,13); 303 (Mt- PdClz, 100); 288 (M+-PdC12-Me, 85); 231 (M+-PdC12-NMeEt, 73); 136 (M"'-PdC12-C5H3~S-CH2NMeEt, 100) Elemental Analysis for C17H25FeNSPdC12 (Calc.) : C 39.74 (40.15); H 4.83 (4.95) (8). 1-Methylthio-Z-ethylthiomethylferrocenyl Palladium Chloride (64) The procedure was the same as that for 57 except that 1- methylthio-2-ethylthiomethylferrocene was used. The product after crystallization gave 0.228 g brick red crystals. Mp. 180-185 0C; yield : 86%. 1H NMR 8 ppm (J in Hz) : 4.32.4.61 (m,C5H3); 4.49 (s,Cp); 3.54.3.66 (d,CI-I2,13); 3.33 (q,aH,SEt,6); 1.61 (t,BH,SEt,6); 2.70 (s,SMe) 35 13C NMR 8 ppm : 88.0 (s,Cl); 81.8 (s,Cz); 72.8, 69.3, 67.4 (d,C3,C4,C5); 70.0 (S,Cp); 29.9 (t,CH2); 26.2 (t,aC,SEt); 14.6 (q,BC,SEt); 20.9(q,SMe) IR (CsI pellet) cm'1 : 3086 (ferrocene C-H stretch); 2922,2960 (alkyl C—H stretch); 1450 (ferrocene antisymmetric C-H stretch); 833,818 (C-H bending perpendicular to the plane of Cp ring); 478 (antisymmetric ring-metal stretch); 325 (Pd-Cl stretch); 297 (Pd-S stretch); 241 (S-Pd-S bending) Elemental Analysis for C14H13FeS2PdC12 (Calc.) : C 34.33 (34.77); H 3.69 (3.75) (9). 1-Methylthio-2-ethylthiomethylferrocenyl Platinum Chloride(65) The procedure was the same as that for 64 except that 0.2 g bisbenzylnitrile platinum chloride was used. The product after crystallization gave 0.223 g yellow crystals. Mp. 213-214 0C; yield : 63%. 1H NMR 8 ppm (J in Hz) : 4.64,4.45,4.44 (m,C5H3); 4.50 (s,Cp); 3.84.3.68 (d,CH2,13); 3.30 (q,01H,SEt,7.4); 1.58 (t,BH,SEt,7.4); 2.71 (s,SMe; th-H=21.7) 13C NMR 8 ppm : 88.0 (s,Cl): 81.8 (s,Cz): 72.8, 69.3, 67.4 (d,C3,C4,C5); 70.0 (s,Cp); 29.9 (t,CH2); 26.2 (t,01C,SEt); 14.6 (q,BC,SEt); 20.9(q,SMe) IR (CsI pellet) 0m'1 : 3086 (ferrocene C-H stretch); 2922,2960 (alkyl CH stretch); 1450 (ferrocene antisymmetric C-H stretch); 833,818 (C-H bending perpendicular to the plane of Cp ring); 481 (antisymmetric ring-metal stretch); 324 (Pd-Cl stretch); 310 (Pd-S stretch); 244 (S-Pt-S bending) Elemental Analysis for C14H13Fe82PtC12 (Calc.) : C, 34.33 (34.77); H 3.69 (3.75) 36 (10). (S,R)-1-(1-Diethylaminoethyl)-2-methylthioferrocenyl Palladium Chloride ((S,R)-66, R=Et, R’=Me, R”=Me) The procedure was the same as that for 57 except that 0.18 g (S.R)-1-(1-Diethylaminoethyl)-2-mcthylthioferrocene was used. The product after crystallization gave 0.252 g purple crystals. Mp. 142- 143 oC; yield : 88%. 1H NMR 8 ppm (J in Hz) : 4.51.4.42 (m,C5H3); 4.30 (t,C5H3); 4.19 (s,Cp); 4.02 (q,CH-CH3,6.6); 1.55 (d,CH3-CH,6.8); 4.10,2.88,2.43 (m,01H,NEt2); 1.97,1.09 (t,BH,NEt2,7.l); 2.74 (s,SMe) IR (CsI pellet) cm'l : 3093 (ferrocene C-H stretch); 2931,2966 (alkyl CH stretch); 1471,1452 (ferrocene antisymmetric C-H stretch); 1173,1258 (C-N stretch); 833 (C-H bending perpendicular to the plane of Cp ring); 680 (S-C stretch); 503 (Pd-N stretch); 337(Pd-Cl stretch); 315 (Pd-S stretch) MS m/e (relative intensity) : 331 (M+-PdC12, 8); 258 (M+-PdC12-NEt2, 66); 243 (M+-PdClz-Me-NEt2, 31); 121 (M+-PdC12-C5H3-SMe- CHCH3NEt2, 72); 58 (Etz, 100); 56 (Fe, 54) Elemental Analysis for C17H25FeNSPdC12 (Calc.) : C 40.58 (40.15); H 4.92 (4.95) (11). (S,R)-1-(1-Di-n-propylaminoethyl)-2-methylthioferrocenyl Palladium Chloride ((S,R)-67, R=n-Pr, R’=Me, R”=Me) The procedure was the same as that for (S,R)-66 except that 0.20 g (S,R)-1-(1-Di-n-propylaminoethyl)-2-ethylthioferrocene was used. The product after crystallization gave 0.262 g dark purple crystals. Mp. 130-131 0C; yield : 89%. 1H NMR 5 ppm (J in Hz) : 451,442,434 (m,C5H3); 4.19 (s,Cp); 4.01 (q,CH—CH3,6.8); 1.55 (d,CH3-CH,6.7); 3.96,2.34,2.19,1.64 (dt,01H,N-n- Prz); 3.32,2.34,1.91 (m,BH,N-n-Pr2,7.1); 1.11.0.64 (t,yH,N-n-Pr2,7.1); 2.73 (s,SMe) 37 IR (CsI pellet) cm:l : 3077 (ferrocene C-H stretch); 2929,2970 (alkyl CH stretch); 1474,1446 (ferrocene antisymmetric C-H stretch); 1172,1250 (C-N stretch); 833 (C-H bending perpendicular to the plane of Cp ring); 693 (S-C stretch); 478 (antisymmetric ring-metal stretch); 513 (Pd-N stretch); 317 (Pd-Cl stretch); 290 (Pd-S stretch) MS m/e (relative intensity) : 359 (M+, 2); 258 (Mt-PdClz-N-n-Prz, 100); 243 (Mt-PdClz-Me—N—n-Prz, 50); 121 (M+-PdC12-C5H3-SM0- CHCH3N-n-Pr2, 69); 72 (86); 56 (Fe, 48); 43(C3H7,50) Elemental Analysis for C19H29FeNSPdC12 (Calc.) : C 41.82 (42.52); H 5.33 (5.45) (12). (R,S)-l-(1-Diethylaminoethyl)-2-ethylthioferrocenyl Palladium Chloride ((R,S)-68, R=Et, R’=Et, R”=Me) The procedure was the same as that for (S,R)-66 except that 0.19 g(R,S)-1-(l-Diethylaminoethyl)-2-ethylthioferrocene was used. The product after crystallization gave 0.226 g brick red crystals. Mp. 130-131 0C; yield : 79%. 1H NMR 8 ppm (J in Hz) : 4.54.4.42 (m,C5H3): 4.37 (t,C5H3); 4.18 (s,Cp); 4.08 (q,CH-CH3,6.8); 1.54 (d,CH3-CH,6.8); 2.71,2.34,1.80 (m,aH,NEt2); 1.97.1.12 (t,BH,NEt2,7.1); 3.36 (m,aH,SEt); 1.72 (t,BH,SEt,7.2) IR (CsI pellet) cm"1 : 3086 (ferrocene C-H stretch); 2931,2973 (alkyl C-H stretch); 1448 (ferrocene antisymmetric CH stretch); 1251 (C-N stretch); 828 (C-H bending perpendicular to the plane of Cp ring); 469 (antisymmetric ring-metal stretch); 516 (Pd-N stretch); 321 (Pd- Cl stretch); 287 (Pd-S stretch) MS m/e (relative intensity) : 345 (M+-PdC12, 6); 272 (Mt-PdClz-NEtz, 30); 243 (M+-PdC12-Me-NEt2, 29); 121 (M+-PdC12-C5H3-SMO- CHCH3NEt2, 68); 58 (Etz, 100); 56 (Fe, 47) Elemental Analysis for C13H27FeNSPdC12 (Calc.) : C 41.16 (41.37); H 5.15 (5.17) use 111) 4.0. 19‘ C-1 38 (13). (R,S)-1-(1-Di-n-propylaminoethyl)-2-ethylthioferrocenyl Palladium Chloride ((R,S)-69, R=n-Pr, R’=Et, R”=Me) The procedure was the same as that for (S ,R)-66 except that 0.20 g (R,S)-1-(1-Di-n-propylaminoethyl)-2-ethylthioferrocene was used. The product after crystallization gave 0.166 g dark red crystals. Mp. 127 0C; yield : 55%. 1H NMR 5 ppm (J in Hz) : 452,439,436 (m,C5H3); 4.17 (s,Cp); 4.06 (q,Cfi-CH3,6.8); 1.53 (d.CH3-CH,6.8); 3.98,2.50,2.14 (dt,aH,N-n-Pr2); 2.29 (m,aH,N-n-Pr2);332.2.29,1.92,0.95 (m,BH,N-n-Pr2); 1.08.0.63 (t,yH,N-n-Pr2,7.3); 3.32 (m,01H,SEt); 1.71 (t,BH,SEt,7.4) IR (CsI pellet) cm'1 : 3081 (ferrocene C-H stretch); 2930,2957 (alkyl C-H stretch); 1457 (ferrocene antisymmetric C-H stretch); 1171,1248 (C-N stretch); 822 (C-H bending perpendicular to the plane of Cp ring); 512 (Pd-N stretch); 318 (Pd-Cl stretch); 299 (Pd-S stretch) MS m/e (relative intensity) : 373 (Mt-PdClz, 2); 272 (M+-PdC12-N-n- Prz, 40); 243 (M+-PdC12-Me-N-n-Pr2, 32); 121 (M+-PdC12-C5H3-SEt- CHCH3N-n-Pr2, 50); 72 (100); 56 (Fe, 33) Elemental Analysis for C20H31FeNSPdC12 (Calc.) : C 43.56 (43.62); H 5.61 (5.67) (14). (R ,S )-l -( 1 -Diethylaminoethyl)-2-isopropylthioferrocenyl Palladium Chloride ((R ,S)-70, R=Et, R’=i-propyl, R”=Me) The procedure was the same as that for (S ,R)-66 except that 0.20 g (R,S)-1-(1-Diethylaminoethyl)-2-isopropylthioferrocene was used. The product after crystallization gave 0.241 g purple crystals. Mp. 123-124 0C; yield : 82%. 1H NMR 8 ppm (J in Hz) : 4.67.4.45 (m,C5H3); 4.41 (t,C5H3); 4.20 (s,Cp); 4.03 (q,CH-CH3,6.6); 1.54 (d,CH3-CH,6.7); 2.62,2.37,1.83 (m,aH,NEt2); 1.97,1.09 (t,BI-I,NE12,7.1); 4.20 (m,aH,S-i-Pr); l.88,1.77 (t,BH,S-i-Pr,7.l) IR (CsI pellet) cm'l : 3093 (ferrocene C-H stretch); 2924,2973 (alkyl C-H stretch); 1448 (ferrocene antisymmetric C-H stretch); 1180,1247 39 (ON stretch); 815 (C-H bending perpendicular to the plane of Cp ring); 470 (antisymmetric ring-metal stretch); 516 (Pd-N stretch); 318 (Pd-C1 stretch); 285 (Pd-S stretch) MS m/e (relative intensity) : 359 (M+-PdC12, 4); 286 (M+-PdC12-NEt2, 100); 243 (M+-PdC12-C3H7-NEt2, 63); 121 (Mt-PdClz-C5H3-S-i-Pr- CHCH3NEt2, 56); 58 (Etz, 55); 43 (C3H7, 74) Elemental Analysis for C19H29FeNSPdC12 (Calc.) : C 42.24 (42.52); H 5.47 (5.45) (15). (R ,S)-1 -(1 -Di-n-propylaminoethyl)-2-isopropylthioferrocenyl Palladium Chloride ((R,S)-7l, R=n-Pr, R’=i-Pr, R”=Me) The procedure was the same as that for (S ,R)-66 except that 0.21 g (R,S)-1-(1-Di-n-propylaminoethyl)-2-isopropylthioferrocene was used. The product after crystallization gave 0.223 g brick red crystals. Mp. 130 oC; yield : 72%. 1H NMR 8 ppm (J in Hz) : 4.65,4.42,4.40 (m,C5H3); 4.18 (s,Cp); 4.03 (m,CH-CH3); 1.53 (d,Cm-CH,6.8); 4.03,2.23,2.09 (dt,aH,N-n-Pr2); 2.41.(m,aH,N-n-Pr2); 2.41,].87,0.81 (m,BH,N-n-Pr2,); 1.07.0.61 (t,yH,N- n-Pr2,7.1); 3.38 (m,aH,S-i-Pr); 1.87,].76 (d,BH,S-i-Pr,7.1) IR (CsI pellet) cm:l : 3093 (ferrocene C-H stretch); 2930,2960 (alkyl C-H stretch); 1459 (ferrocene antisymmetric C-H stretch); 1170,1245 (C-N stretch); 817 (CH bending perpendicular to the plane of Cp ring); 471 (antisymmetric ring-metal stretch); 514 (Pd-N stretch); 314 (Pd-Cl stretch); 286 (Pd-S stretch) MS m/e (relative intensity) : 387 (Mt-PdClz, 2); 286 (M+-PdC12-N-n- Prz, 81); 243 (M+-PdC12-C3H7-N-n-Pr2, 57); 178 (M+-PdC12-C5H5-N-n- Pr2-C3H7, 29); 121 (M+-PdC12-C5H3-S-i-Pr-CHCH3N-n-Pr2, 97); 56 (Fe, 33); 43 (C3H7, 33) Elemental Analysis for C21H33FeNSPdC12 (Calc.) : C 44.60 (44.67); H 5.84 (5.89) 40 C. General Procedure for Hydrogenation Reactions The palladium catalysts (1.0 X10'5 mol), 4.5 mL acetone and 3.725 X10‘3 mol substrate were added to a 100-mL pressure bottle equipped with a pressure gauge and a stirring bar. The bottle was evacuated and filled with H2 several times, then fixed at 62 psi. The uptake of hydrogen was monitored by the pressure drop. (1). 1,3-Cyclooctadiene Following the general procedure, the products were distilled from the catalysts and analyzed by using 1H NMR and GC. The 1.3- cyclooctadiene / cyclooctene ratio was determined by integration of the 1H NMR in the olefin region. The (l,3-cyclooctadiene+cyclooctene) / cyclooctane ratio was determined by GC. (2). Acrylic Acid The hydrogenation product was distilled from the catalyst and analyzed by using 1H NMR. (3). Phenylacetylenes Phenylacetylene, diphenylacetylene, bromophcnylacetylene, methylphenylacetylene, and ethylphenylacetylcne were used in the hydrogenations. The products were distilled from the catalysts and analyzed by using 1H NMR. (4). Asymmetric Hydrogenation of Aminoacids The rhodium catalysts were prepared in situ by adding 20.4 mg AgBF4 to 13.8 mg [RhNBDCllz (3x10:5 mol) in 4.5 mL methanol. After stirring under argon for 30 min, appropriate amount of ligands were added (ligand to metal ratio=1.05:1). One hour later the substrate (2x10'3 mol) in 4.5 mL methanol was added quickly to the reaction mixture and the hydrogenation was performed as described. Th WE 41 The products were worked up according to the reported procedure.86 The conversion was determined by using 1H NMR and optical purities were determined by checking the rotation on a polarimeter.87 42 D. Asymmetric Grignard Cross-Coupling Reaction A 0.05 mmol sample of the appropriate catalyst was placed in a 100-mL round-bottom Schlenk flask which was then evacuated and filled with dry argon several times. After being cooled to -78 °C. 1.41 g (10.0 mmol) l-phenylethyl chloride 31 in 20 mL dry ether was added via syringe to the flask which was then stirred for 2 h at room temperature. The reaction vessel was charged with 10 mL allylmagnesium chloride (2 M solution in THF) via syringe at -78 °C. The reaction mixture was stirred at room temperature for 36 h, then hydrolyzed with 10 mL 10% HCl. The organic layer and ether extracts from the aqueous layer were combined, washed first with saturated NaHCO3 solution, then with water, dried over anhydrous MgSO4 and evaporated to dryness. The product was chromatographed on a silica gel column to give 4-phenyl-1-pentene 32 (90-96% yield). Oxidation of 4-phenyl-1-pentene to methyl-3-phenylbutyrate The reported procedure145 was followed : A 0.906 g sample (6.2 mmol) of 4-phenyl-1-pentene 32 was dissolved in 160 mL t-butyl alcohol. To this was added a solution of 2.48 g (18.0 mmol) K2CO3 in 120 mL of water and a solution of 10.26 g (48.0 mmol) sodium periodate and 1.26 g (8.0 mmol) KMnO4 in 120 mL water. The solution was adjusted to pH 8.5 with 2N aqueous NaOH and stirred overnight. t-Butyl alcohol was evaporated under reduced pressure; then the aqueous solution was adjusted to pH 2.5 with concentrated HCl. Sodium bisulfite was added slowly until the solution become off- white. The aqueous solution was extracted twice with ether; these extracts were combined, washed, dried over anhydrous MgSO4 and evaporated. A solution of the resulting acid (0.59 g, 3.5 mmol) and p-toluenesulfonic acid (80 mg) in 20 mL of MeOH was refluxed for 3 h. the solvent removed, and the residue extracted in ether. The ether solution was washed with 10% aqueous NaOH, dried over anhydrous 43 MgSO4 and evaporated. The residue was distilled at 110-130 °C (2 mm) to give methyl-3-phenylbutyrate 33 (75-85%). A 90 mg sample of the chiral shift reagent, tris(d,d-dicampholylmethanato) europium(III), Eu(dcm)3, was placed in an NMR tube under argon and 0.15 mL 1 M solution of methyl-3-phenylbutyrate 33 in CDCl3 was added. The solution was diluted to 0.5 mL with CDCl3 to 0.16 M in Eu(dcm)3 and 0.3 M in methyl-3-phenylbutyrate. Argon was bubbled through the solution for one minute to eliminate oxygen; the NMR tube was then evacuated and sealed. The methyl ester proton of the two diastereomers gives two singlets; their ratio yields direct measurement to the enantiomeric excess. RESULTS AND DISCUSSION A. Synthesis of Ferrocenylamine Catalysts 1. Synthesis and Characterization of Ferrocenylamine Ligands (1). Ferrocenylamine Sulfides The reactants, l-Dimethylaminomethyl-2-alkylthioferrocene (34,35), (R,S)-l-(l-dimethylaminoethyl)—2-alkylthioferrocene ((R,S)-48,(R,S)-49) and (S,R)-1-(1-dimethylaminoethyl)-2- alkylthioferrocene ((S,R)-47), were prepared according to the reported procedure.85 Dimethylaminoferrocenyl sulfides (34,35) were first converted to sulfidoferrocenyl ethylacetate, then react with diethylamine or di-n-propylamine to give diethylamino ferrocenyl sulfides (37-40) and di-n-propylaminoferrocenyl sulfides (41,42) , respectively.” The chiral ferrocenylamine sulfide ligands ((S,R)-50-(R,S)-55) were also prepared in this way with some modification (Scheme 6). All the ligands thus prepared are yellow to brown oils except when the thio substituents are 4-chlorophenylthio 39 and 4-tolylphenylthio 40, which give yellow and brown crystals, respectively. The overall yield ranges from 20% to 85% dependent on the steric strain of the ligands. “K 5” R" =‘H “K -‘H @‘S‘W @635 @524. is sq AC20 1:9 sn' HNRZ 1:9 88' R'= H FI"- H R‘= H Fl:- Et R'= Me, Et (34,35) R’= Me (36) R'= Me, Et, R'= CH3 ©Cl,©-CH3 (37-40) R'- Me ((53)-47) HCI R_ ”p, R" EI, i'Pr ((R,Sf48,49) R'= M8, EI (41.42) R- i-Pr, i-Bu A . '19 SW ”K151 '16 SM. R r P" (46) R'- CH3 Fl- Et, n-Pr R'= Me ((S,R)-50,51) N335! R'= El ((R,S)-52,53) R'= i-Pr ((R,S)-54,55) Scheme 6 46 The 300 MHz 1H NMR data for the achiral and chiral ligands 37-(R,S)-55 are tabulated in Tables 1 and 2; representative spectra are shown in Fig. l for achiral ligand l-Diethylaminomethyl-Z-ethyl thioferrocene (38) and in Fig. 2 for chiral ligand (R,S)-1-(1-Diethyl aminoethyl)-2-ethylthioferrocene, (R,S)-52. In both cases, protons of the unsubstituted cyclopentadienyl ring appear as a singlet due to the free rotation around the Fe-Cp axis in ferrocene.88 It is a good indication of single-ring substituted ferrocenes. Assignment of the substituted ring protons H3, H4, H5 is difficult because of the ambiguous shielding or deshielding effects of the substituent.39'9l The aminomethylene and thiomethylene protons in compounds 38, 42, 44 and (R,S)-52 are diastereotopic and their signals show up as two multiplets due to the additional splitting of the neighboring protons. For the achiral ligands, a striking feature is the sensitivity of the chemical shift difference of the two diastereotopic methylene protons between the Cp ring and the amino substituent to the steric crowdedness at the B-carbons of both the amine and the thioether substituents (Tables 3, 4). 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Table 4 Change in chemical shifts for chiral ferrocenylamine sulfides Compound N-CH2 S-CHz 8 A 8 8 A 8 (am-50 2.46, 2.31 0.15 2.29(SMe) (R=Et,Fl'=Me) (am-51 2.28, 2.22 0.06 2.28(SMe) (R=n—Pr,R‘=Me) (R,S)-52 2.48, 2.29 0.19 2.90, 2.63 0.27 (R=Et,R'=Et) (3.3-53 2.31. 2.21 0.10 2.84. 2.61 0.22 (R=n—Pr,R'=Et) (3.3-54 2.49, 2.27 0.22 3.52 (S-Cfl) (R=Et,R‘=i-Pr) 1.15, 1 .06 (SCCH3) (3,51-55 2.33; 2.20 0.13 3.42 (s-cw (R=n-Pr,R'=i-Pr) 1 .15.1.07 (scone) (3.3-488 2.73. 2.63 0.10 (R=Me,Fl'=Me) a (R, S )-1-methylthio-2-(1-dimethylamincethyl)ierrocene, ref. 124 54 The 75.5 MHz 13C NMR of achiral and chiral ferrocenylamine sulfides 37- (R,S)-55 are given in Tables 5 and 6, respectively. Tentative assignments of the chemical shifts for these compounds are made by comparison with similar studies75~77-37 and by 13C DEPT analyses. Typical off-resonance and DEPT 13C NMR spectra for compound 37 are shown in Figs. 3 and 4 whereas spectra of other compounds are shown in the appendix. In the off-resonance spectrum both the 0t- and B-carbons of diethylamino group at 46.3 and 11.7 ppm appear as singlets due to the fast inversion of the pyramidal nitrogen atom. The methylthio group appears at 20.5 ppm. C1 was assigned at 87.4 ppm since it was a neighbor to a more electronegative element, 8; whose inductive effect is more important than the resonance effectloo, thus C1 appear at lower field than C2 (83.4 ppm). The assignment of C3, C4 and C5 was difficult due to complicated resonance and inductive effects of the sulfido and amino substituents.100 The unsubstituted Cp signal appeared at 70 ppm as an intense peak. The quaternary substituted carbons; C1 and C2 ; were not shown in the DEPT spectrum, whereas all other protonated carbons were detected. By adopting this pulse sequence in 13C NMR, primary, secondary and tertiary carbons are easily identified. The infrared data of compounds 37 - (R,S)-55 listed in Tables 7 and 8 are assigned based on the available literature93'101 and other ferrocenylamine sulfides reported previously.32'83 Two bands near 1000 and 1100 cm'1 are important features of ferrocene derivatives with unsubstituted rings. The 08 stretching bands appeared at 600-700 cm'1 and that for C-N stretching absorbed at about 1200 cm‘l. All other stretching, bending and breathing bands are generally consistent with the literature values.93'101 Fig. 5 shows the spectrum for compound (S,R)-50. «.8 «.8 88.38% «.8 8.8 8.8 «.8 a8 8.8 m: .«3 c8 «.8 8.8 e c mm. 8.8 51:83: 8.: o. 5 .. .« 8.8 3.. m: .0: «.2 «.8 8.8 n e «.8 83m. 3; 8.8 h : 98 98 8.8 n. K 8.: .8 m8 8.8 « q «Km Aux-.mfeum. «.8 h. : 98 «.«m 8.8 8.2 ...«« n8 «.8 8.8 p c 888 .«8. .39 «.8 ..>_sa..5 8.8. .98 m. I .8 «.8 m. 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In order to assure the planar chirality of the chiral ligands, CD measurements were performed for some representative ligands. The CD spectra of compounds (S,R)-51, (S,R)-52, (R,S)-54, (R,S)-SS, (R,S)-1-(1-dimethylaminoethyl)-2-phenylthioferrocene (R,S)-8l, and (S,R)-1-(1-dimethylaminoethyl)-2-2’-(bismethylthio)ferrocene (S,R)-82 are shown in Figs. 6 and 7. The absorption spectrum of ferrocene has two long wavelength bands at 325 and 440 nm assigned to d-d type transitions.103 The CD spectra of chiral ferrocenylamine sulfides reveal optical activity arising from the planar chirality around these two absorption bands. The assignments of planar chirality to these new ferrocenyl sulfides were made possible by comparison with known chiral ferrocenylphosphines.15vl7 (Fig. 8) The ferrocenylsulfides with planar chirality of R configuration (S,R)-51, (S,R)-52 and (S,R)-82, all exhibit negative Cotton effects around 330-340 nm and positive ones around 440-450 nm, whereas negative Cotton effects are observed in the cases of (R,S)-54, (R,S)-55 and (R ,S)-81 whose chiralities are S. 1 L L l 1 L l l L 1 To ’ ‘ :12 , - 5 -- 4 1 " r r T I r r r r r J" 170 01. 0” ”0 01. mm «m — """" C ++++ H EH3 ‘CZHS 5 3 ‘cau, ’CH3 \N. \N-o 3 © '0 H 'can en, | S | S l -——N I I C 0 Fe CI'CH3 Fe ChCH, Fe "CsH7 er- en © 0.”, 3 a (9'3'54 (R,S)‘55 Figure 6. CD spectra of (am-51, (3.3-54 and (3.3-55 in chloroform 65 Ill IPI IICI IY X l0 Mull ml mu l t. l 310 370 ‘30 ‘90 550 610 HAW (III) +++++ 9H3 c SMe SEl 2 n r l r Fe SPh Fe C-NMez Fe c-NEle sue (n,S)-e1 (S,R)-82 (s,n)-52 figure 7. CD spectra of (am-52, (33)-82 and (H.5‘H1 in chloroform 66 I l _ I - . "W : m . (S) (n) PPFA I I I I I I I I I 1.01 I I I I l I I \l [91x10'3. 104 .'oo4 (S'Hfll-PPFA (WI-(SHIPFA Figure 8. CD and UV spectra of (S,Fl)-PPFA and (Fl, Sl-MPFA in chloroform 67 (2). Synthesis of Ferrocenyldisulfide Ligand The 1,2-disubstituted ferrocenylsulfide ligand can be prepared by reacting the corresponding ferrocenyl ethylacetate with ethanethiol, but the yield is low (ca. 10-20%). An alternative route was adopted and ligand 5 6 was generated in situ by first converting methylthioferrocenyl ethylacetate into halide, then stirring it with NaSEt.1°4 The yield improved to 84%. The 1H NMR and off-resonance 13C NMR are shown in Figs. 9 and 10. The two diastereotopic thiomethylene protons in the ethylthio group show a quartet which is different from those of the aminomethylene protons in the ethylamino group. The free rotation of the ethylthio group suggests that this ferrocenyl sulfide ligand is sterically more relaxed than those of ferrocenylamine sulfides. The 13C NMR spectrum assignment for the two thioether groups can be made by considering the different deshielding effect exerted by these two substituents. Thus, the unsubstituted Cp ring was assigned at 70.0 ppm, C1 and C2 at 88.0 and 81.8 ppm respectively; C3, C4, C5 appeared at 72.8, 69.3, and 67.4 ppm; the methylthio, group (C6) at 20.9 ppm ; C9 at 14.6 ppm. Similar to the 13C NMR assignments of the ferrocenylamine sulfide ligands, the methylene carbon (C7) between the Cp ring and the sulfide substituent should appear at lower field than the thiomethylene carbon (C3). 80, C7 was assigned at 29.9 and C3 at 26.2 PPm- An interesting feature arises if one compares the chemical shift of methylene carbons (C7, C3) in the ferroceneylamine sulfide series and compound 56. The C7 chemical shift in the former series appeared at around 50 ppm, but in compound 56 it appeared at around 30 ppm. Obviously, the more electronegative N atom pulls electron density from it’s nearby carbon group more efficiently than does the less electronegative S atom; thus, the carbon groups near 66 on 3 52.02.... mzz I. £2 Sm .m 2%: o-m m.m a.v m.v rPhbbPerbhprhbrhrrer J j]. 2 69 n 3 on 8 .o 5.58% 0:2 0.... 83:83 23 820 .2 2:9... at cm mm on a O! a? on an 8 an on an on no 8 8 thP-btb-hbhbpbbbthDFIF-bbbb-bbbPhDPh-PPDPDthPbPhrbhbhbbhbbebbnrhbbbbbbPhbbberbhbnbbbbbebebLLbb iii a0 1"!- 7) no 7 o0 no m0 v06 ill III llIVIIII b I D’DI b ll 1 tI‘IIII I I I I! 70 the 8 atom appear at higher field. The same argument holds for carbon C3. The chemical shifts of C9 appeared at about the same field (12-15 ppm), thus the inductive effect apparently influences only the nearby carbons (or-C) significantly. The BC is less sensitive-149(3) As expected, the IR C-N stretching bands around 1150-1190 cm'1 were not observed. (Fig. 11) Disappearance of C-N absorption in this region solidifies the ON stretch assignment made in the ferrocenylamine sulfide ligands. The mass spectrum is shown in Fig. 12. The molecular ion peak was observed again with a 43% relative intensity at We = 306; other important fragments include M+-SEt (245), M+-C5H5-Fe-C5H3 (124), Fe+(56), C5H5+(65). 71 C'C\ SEI l I Fe SEt (55) S)-53 In. Figure 11 .Comparison of IF! spectra of 56 and (3,5363 in 1000 cm'1-1500ourI region 72 0m .0 82.00% 032 .w. 059... perm ma...“- QwN 3H 3.: u .. P b. b . F . P b b fit-P4! pry arm ~.~ i ,: _ : 3N , ,, f . 8— vm— Q...— r hm . w¢N 8“ 1 T w.; .- .5 . ma— am «03 no . f Zn.— . . «mm On. - mW VN— . .20 © . l: _.m .8 73 2. Preparation of Palladium and Platinum Complexes The procedure was similar to that used for preparation of other ferrocenylamine sulfide complexes reported previously;32~33 however, shorter reaction times were employed, i.e., 8 h for palladium or 2 days for platinum complexes. Schemes 7,8 show the preparation of these heterobimetallic complexes. These palladium complexes are soluble in polar organic solvents such as methylene chloride, chloroform, acetone and acetonitrile. The platinum complex is soluble in acetone and slightly soluble in the other three solvents. Pure samples can be obtained by recrystallization from either methylene chloride/hexane or acetone/ether. The catalysts obtained are stable for months without deterioration or decrease in catalytic activity. Tables 9 and 10 show the 300 MHz 1H NMR data for these achiral (57-65) and chiral complexes ((R,S)-66-(R,S)-7l) respectively. Since formation of the distorted six-member ring between the ligands and the metal chloride prohibited free inversion of the pyramidal N, the methyl region of the diethylamine group and that of the di-n-propylamine group appear as two triplets instead of the one present in the pure ligands. Donation of the lone pair electrons of the amino and thioether groups to palladium during complex formation causes the chemical shift of both groups to appear at lower field than did those of the free ligand. The thiomethylene and aminomethylene protons were assigned by 2D COSY experiments. A typical spectrum for achiral complex (R ,S)-68 is given in Fig. 13. The two thiomethylene protons, for example, are assigned at 6:3.17 and 3.40 ppm since they are correlated with the methylthio group located at 1.70 ppm. The two sets of aminomethylene protons are assigned as follows : one set at 2.58 and 3.15 ppm is correlated to the methyl group at 1.04 ppm; the second set at 2.23 and 3.91 ppm is correlated to the methyl group at 1.91 ppm. (PhCN)2PdCI2’ 74 :f\ Cl (1’ N>Pd\ R-EI R'- Me,Et, 00'. GCHa (57.50) Ran-Pr R's Me, El (61 .62) CH3 Cl quit; S\ / Pd / (PhCN)2PdCl2 / \ F N ! e v F!6 K 5‘ CI (53) gs S’Csz @spz’fi (PhCleMClz §-—\M— cu ©”“’ @“3 \- M-Pd (64) Map! (55) Scheme 7 SR' @ We 0’ N32 9”: Qt NR2 Fe 59' 75 .3 or s c \Pd\ (PhCN)2PdCl2 flaN/ C' —> Fe C I \ © H R R8 EIJ'PP! R'sMe ((S,R )o65,67) :3,“ a N‘L (PhCN)2PdCl2+ @s \Fid\ CI +@9R CI R'- E! 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SAMJE v 02.3 ado a... ..o ada o ...:. v ..mn.~. ..mux. 3.3.3 m n63. ado 3.3 «ha ado m6 ...:. 5v fining. Elfin. m We... ...:a .5. m... ...ca 3 .. N CSHR .53.. 3.2.5.. . . a. P. $5.35. 3... . 0.. . 2m. .2553. A.x...,..00.0m ..c....0>..ou 2.3:... 0.. 0:00.52 *0 0:05 0.. 0...... .5. 0.7.32.6 ...:... 0530... ..0......:... .2. no .a «.02....m..-.20220.:.1800}?! 3.2.2.50 .220 25:; .. «05.2.2533... .9 5.38022: 02:03 2 2...... 94 .ll'. .IIII‘I’I‘IIvI-lllll'llll 5.no new ..co ado 37.9.3022: 0.... ...:...— .0.=....0..:.0. .:00. .0 0.8.00- '-' I,. II .II I'Il'l'll'l||' III-l 5.50 e... 5.50 a... ~60 o... 0.2. a... .05.. .00. n»..>..00.0m :0.a.0>:0U mN ad ad 550 5.50 053:... 8 0:00:03. 9.. A 05800.03 + 05.003050. 03.002030 . ¢.v r ~. .lllII,Illnlll'l'lI‘ll-It'll]l.|l||ll:'|'|""lllll'll'll1|"ll|‘ 23.: 0. A... n... 6.2.3:... .0 .05 TEX 356 $0.315 ..0 .0... «6:8... E... c. on v 0.... c. av m ES .0 me ~ 5... v A... . :2: 2...... ...m 0.0000... ...:m 0 0.3.00... .0 .00..m.0..0.0...000.0au-m.. .0 5:303:12 o. 03...... 95 efficacy of the bond-breaking step and the oxidative addition of H2 the reaction rate can be increased. The reaction rate for catalyst 64, which bears two sulfide groups, was much slower than that for other catalysts with one sulfide and one amine group. A possible explanation for this behavior is stronger Pd-substrate bonding which results because the ethylthio group is not as bulky as the amine group; thus the reaction rate is reduced. Attempts to investigate the influence on the catalytic activity of replacing l-dimethylamine substituent by even more bulky di-i- propylamine, di-i-butylamine or diphenylamine failed. With the more bulky substituents the palladium complexes become inaccessible. The effect of initial reaction pressure on the reaction time, yield and selectivity is shown in Table 16. The conversions were all 100% and selectivity decreased slightly as the pressure increased. This catalytic system has the best performance at 62 psi (entry 2); however, hydrogenation can still be carried out efficiently at 20 psi (ca. 1.4 atm). To evaluate activities of new complexes reported here, catalysts 62 and (R,S)-69 are compared with previously known Pd complexes (Table 17). The data for entries 4, 5, and 6 (complexes with one dimethylaminc substituent and with sulfide substituent(s) at either one or both the two Cp rings) show hydrogenation activity about three orders of magnitude faster than that of the chelating bis(phosphine)132 (entry 1) and about the same as that of the amine catalyst. (entry 2)133 The activity of (R,S)-69 is about five orders of magnitude faster than that of the chelating bis(phosphine) catalyst. Modified sulfido substituents show about the same activities (entries 4,5,6) while entries 7,8 show the difference in replacing the dimethylaminc group with the di-n-propylamine group. Achiral catalyst 62 (entry 7) is 5 to 20 times as active as entries 4,5; chiral catalyst (R,S)-69 is even more active (28-117 fold). Thus, we were 96 'll|"""“'-l"|'ll"'||'l||'ll""" 5.8.0.. 0.00....00.3..-=-202=uxn0.0.00.0:00. 0 .00. 0.00...mm..0...é-2000..0000.00.0000. . 0 ...03 02,—. 000.000 +0.5 2. 000.00.000.030. «.0». m 0 ...03 02,—. 000.000 +0?— bn 000.00.000.0A0-m.. 0.0m 0 Nu. 000.000 +0.5 0N 000.00.820.34... and 0 mm. 000.000 +0?— uu 000.00.330.30.— 00... n mm. 000.000 +0?— g 03.00.000.030.— mnd 0 mm 000.000 +0.... 0N 000303020000; ~00 m 00. 2.3.2 00.. 2 2.8.3. «0.0.0.... 0 cm. 0000.0. +0.... no 000.005.3300-... :8... . .0: .00>.0m .302 De... 0.0.30.5 30.069.25.00. ...:”.— 0.0m .0...0. a..>..0< 0.30.00 0... ..0 08500.00 00000002 0. 00005 ..0 00.30033»: 0000000080: 0>..00.0m 2 0.00... 97 able to improve the activity of the ferrocenyl sulfide complexes by up to a factor of two by modifying amine substituents rather than sulfide substituents. In this hydrogenation we have demonstrated that the chiral methyl group as well as the alkylamino group effectively influence the reaction rate. These new catalysts performed at high rate (up to 1.1x104 mol/mol-Pd-h) with retention in conversion and selectivity. 98 b. Hydrogenation of Acrylic Acid Hydrogenation of acrylic acid was performed in a similar way to the above hydrogenation by using compounds 58, 59, (R,S)-68, (R,S)-69 as catalysts. Results are presented in Table 18. The conversions were all 100% with propionic acid as the sole product. Again, the chiral compounds catalyzed the reaction at a faster rate than achiral catalyst 58 and 59. As can be seen from the table the catalytic abilities of these new compounds are comparable to those of other ferrocenylamine sulfide catalysts. It was therefore assumed that these new series of catalysts would be able to catalyze hydrogenations similar to those other ferrocenylamine sulfide catalysts do.124 It should be noted that these new catalysts retain the same degree of selectivity and reactivity as do other similar ferrocenylamine sulfide catalysts. Table 18 Hydrogenation of acrylic acid at 80 psi H2 pressurea Catalyst Rx. time Conversion Turnover rate Rel. (mol/mol pd.h) 58 (R=Et.Fl'=Et) 1 h 100 °/0 372.5 this work 59 (R's4-PhCI) 1.33 h 100 °/0 280.1 this work (ES—68 (R=Et.R'-.-Et) 0.5 h 100 °/. 745.0 this work (3.3-69 (Ran-Pr) 0.5 n 100 °/. 745.0 this work (S,Rl-TI" 1 h 100 °/0 372.5 124 78°(R0Me.Fl'=p-tolyl) 1 h 100 °/. 372.5 124 a 3.725x 10'3 mol substrate. 1x10-5 mol catalyst, 4.5 mL acetone, room temperature. hydrogenation product: propionic acid '3 (Sfll-l -dimethylaminoethyI-Z-Z'-p-tolylthiolerrocenyl palladium chloride C1dimethylaminomethyl-Z-p-tolylthiolerrocenyl palladium chloride 100 c. Hydrogenation of Phenylacetylenes The selective hydrogenation of acetylenes to olefins is of great practical importance in connection with the problem of hydrotreating olefin cuts from petroleum to remove a compound with a triple bond, so that the olefins can be used in polymerization reactions. The majority of hydrogenations of acetylenes are carried out on heterogeneous catalytic systems60 or on polymer-supported homogeneous catalysts. (homogeneous-heterogeneous catalysts)‘51'67 Therefore, it should be interesting to investigate the activities and selectivity upon hydrogenation of phenylacetylenes by ferrocenyl thioether-based catalysts. Several phenylacetylenes have been tested in this hydrogenation; substrates include phenylacetylene, diphenylacetylene, methylphenylacetylene, ethylphenylacetylene, and t-butylphenylacetylene. Reactions were either allowed to go to a totally hydrogenated alkane or were controlled at 8.5 psi pressure drop so that the alkyne was hydrogenated only to the alkene. In general, phenylacetylene hydrogenation results parallel those of conjugated double bond hydrogenations; they are presented in Tables 19-20. (1). Hydrogenation of Phenylacetylene to Ethylbezene , Table 19 shows hydrogenation results from uncontrolled reactions. Again, chiral catalysts (S,R)-67 and (R,S)-7l catalyze the reaction more efficiently than the achiral ones. Entries 3 and 5, in which the amino substituent dimethylaminc in achiral complexes is replaced with diethylamine, show about a 2 fold rate increase; while changing diethylamine to di-n-propylamine enhanced the rate about 4 times (entries 1 and 4). A comparison of entries 1, 3 and 5 demonstrates that both the sulfido and the amino substituent influence the reaction rate, especially when the sulfido substituent is 101 00.5.5 5200.00 .282.0..o_......_o.0-mz.90-0.2.8:E03530-10.0. o 02.0.00 50.00.00 ...:009.08.520.00-..:..0800200.308...-F a 0.0.0.0050. 0.00. 05000.0 0... .00 00 .0 000.000 ..0. 0.0 00.20.00 .00. 0.0.... 0.000000 .00. 0-0. .6000 0 c. .0 8. o z 0. 00......0. 0 0.0.0. 8. 0 se 00 00...»... 000...... $6.... 0 53 8. 0 s... 00 32...... 00%... 00.8.0. 0 0.00. 8. o c 0 320mm 0.2.0. a... 0 0.00. 8. o n 00.0 .22»... 0.01.0.8 0 0...... 0.00 0... se 00 2220»... .0158 0 0. z. 0.00 0.00 c 0 0.9.0.0»... .010. 00 0 0. z. 8. o g 0 cm»... .010...» . 2.3 .252... Sm. .o>o...=..._. oc>x_ entry 5 > entry 1) One interesting feature arose when chiral catalyst (S,R)-77 (entry 8) was used. This compound has two p-tolylthioether groups on both the ferrocenyl Cp rings. Yet, it showed no enhancement in the reaction rate, only a decrease in catalytic activity. It is possible that the additional p-tolylthioether group at the lower Cp ring inhibits formation of the substrate-metal adduct, a requirement for the catalytic reaction to take place. However, one cannot rule out the possibility that addition of the second thioether group to the ferrocenylamine catalyst changes the electronic character that produces decreased activity. (2). Selective Hydrogenation of Phenylacetylene to Styrene (a). Effect of Catalysts The results for hydrogenation of phenylacetylene to styrene by a variety of ferrocenylsulfide catalysts are collected in Table 20. The reaction was controlled at 8 psi H2 pressure drop, thus the phenylacetylene was expected to half-hydrogenate only to styrene. Chiral catalysts were not used in this hydrogenation since they catalyze the reaction so rapidly that to half-hydrogenate the substrate might be difficult. Results showed that selectivity to styrene can be achieved at about the 90% level with good conversion with compounds 57 and 58 as catalysts. It also showed that hydrogenations by less active catalysts gave better selectivities. Attempts to enhance the selectivity by modifying the catalytic conditions (such as catalyst, H2 pressure) were unsuccessful. Probably, in our catalytic system, hydrogenation of phenylacetylene to styrene and that of styrene to ethylbenzene are sequentially differentiable. Thus, styrene cannot be obtained alone in this system. 103 Tablezo Hydrogenation of phenylacetylene to styrene: effect of catalysts catalyst reaction time °/. alkane °/. alkyne conversion selectivity turnover rate (mol/mol 96.11) 57 24 h 89 11 100 89.0 15.5 58 2 h 88.4 10.3 98.7 89.6 367.7 59 1 h 80.4 14.0 94.4 85.2 351.6 60 32 min 80.7 9.8 90.5 89.2 623.0 62 1 h 83.8 8.7 92.5 90.6 344.6 a 3.725x 10-3 mol substrate. 1x10-5 mol catalyst. 4.5 mL acetone at 80 psi H2 pressure. room temperature. reactions were controlled at 8-8.5 psi pressure drop 104 To show how competitive these two reactions were, a separate experiment was carried out to hydrogenate styrene to ethylbezene at identical conditions. The result revealed that the turnover rate of the above reaction is about twice as fast as the rate of hydrogenation of phenylacetylene to styrene. Similar results were found by Muetterties, et al. in the hydrogenations of phenylacetylenes catalyzed by phosphine-based rhodium clusters.134‘137 Since hydrogenation of phenylacetylene is very slow relative to the alkene hydrogenation sequence, the slow but selective hydrogenation of acetylene catalyzed by these palladium ferrocenyl catalysts can be rationalized by a much higher reactivity of the catalyst precursor or intermediate towards alkynes relative to alkene and to a different hydrogenation sequence for conversion of alkene to alkane. Indeed, this is the case in our catalytic system. Phenylacetylene was added to complex (R ,S )-68 in approximately a 2 to 1 molar ratio in CDCl3 at room temperature and the reaction was monitored by 1H NMR. After about five minutes Pd-S and Pd-N bond- dissociation were observed. At the same time two new sets of signals were detected. Formation of the substrate-metal adduct was completed about one hour later. (see Fig.19) Addition of styrene to the same catalyst revealed no change in the spectrum after an 8 hour period. At this point it is clear that the greater affinity of phenylacetylene for the catalyst has a powerful influence on the selectivity. We tried to profile the reaction coordinate by performing the reaction at 1 atm, but the reaction did not take place at such a low H2 pressure. (b). Solvent Effects The influence of solvent upon hydrogenation of phenylacetylene was investigated under the same conditions and the results are shown in Table 21. 105 (0) 35' ' 3.5 ' ' ' 'z.!.' ...:.B.. ' 33' T7153 ' ' ’1} (b) . (a) l l l | l l fruit]!I1!IIIIt'lfIslurrI1t1IvtvivI1ft l 3 2 1“ Figure 19. Phenylacetylene + ($53-68, (a) 5 min (b) 30 min (c) 1 h 106 Table 21 Hydrogenation of phenylacetylene to styrenea : effect of solvents solvent reaction time % alkene % alkyne conversion selectivity turnover rate (monol pd.h) acetone 1 h 88.4 10.3 98.7 89.6 367.7 THF 22 h 90.2 5.8 96.0 94.0 16.3 CH3CN 24 h 89.3 4.7 94.0 95.0 14.6 CH3CN 31 h 91.0 9.0 100.0 91.0 12.0 CHzclzb 24 h a 3.725x 10‘3 mol substrate, 1x10°5 mol catalyst 58. 4.5 ml. acetone at 80 psi H2 pressure. room temperature, reactions were controlled at 885 psi pressure drop b reaction incomplete. only 2.5 psi pressure drop was observed 107 Consistent with the hydrogenation of 1,3-cyclooctadiene, initiation of the hydrogenation sequence required polar solvents again in this case to create a vacant coordination site. CH2C12 is inadequate since it is not a good coordinating solvent. Among those polar solvents employed in this hydrogenation. acetone again is the best choice, though its selectivity is slightly lower than that of others. Since the faster reaction rate (thus the higher turnover rate) may compensate for the slight loss in selectivity, acetone was adopted as solvent in this hydrogenation. (c). Selective Hydrogenation of Disubstituted Acetylenes Because phenylacetylene was selectively hydrogenated successfully, a series of phenylacetylenes was investigated under either controlled or fully hydrogenated conditions. Results are shown in Table 22. Compare entries 1 and 4; here the chiral catalysts (11,8)- 68 no longer possess higher activity than achiral catalyst 62. Instead, (R,S)-68 is 1/7 as fast as 62. Again, as in the catalytic hydrogenation of phenylacetylene, the l-l’-Cp ring disubstituted catalyst (R ,S )-77 requires a longer time to complete the reaction. It takes about twice as long to hydrogenate diphenylacetylene as to hydrogenate phenylacetylene. Recall that in hydrogenations of the less sterically hindered phenylacetylenes the chiral methyl group exerts a powerful influence on rate enhancement. In this case, besides the inherent affinity of the substrate to the catalyst, one also must consider the steric bulkiness of both entities. Thus the most steric hindered chiral 1-1’-disubstituted catalyst takes the longest time to complete the reaction. Yet, because of it’s stereorigidity, it also yielded the best selectivity among the catalysts tried. The chiral catalyst (R,S)-68, which is considered more bulky than (R ,S)-79, but less crowded than (R ,S)-77, performed at a moderate rate. We see that in order to obtain good selectivity and 0.0000... 0.030. ..._>_.00_00 .00.0 05000.0 .00 0.0 .0 00:00:00 0.03 000000. 0 0000...... 0.0.50. 0.2.00.3 0 0000.00 05.02.00 30000009250690...-~-_..0.0.000.E0...0.0E.0-.0 0000.00 50.00.00 0.008..0.0.0...._o.0-0_0-.0-0-..0..02.50.05055..-.-. 0 .0. 0 05.0.0060. E00. 05000.0 0: .00 00 .0 000.000 ..0. m... ..0.._0.00 .00.. 0.0.x. 0.000000 .00. 0:0. .600...” 0 8 m 00.00 00. .. . 0.00 0.0 00 0030 00...»... 00 000 00. .. . 00 0 00 ..mu... 00.1.0. 00 0.0 00. .. 0. 00 o .0 00.1.0 .00. 00.0.0. 000 00. .. 0.. 00 0 00 00.7.0 .0»... 000 0.0 00. .. 0.00 00 0 .0 0006.0. 000 8. .. 0 00 0 00 00...... 000»... 00 02.00.00 00.0.2000 00... .00 3003.0 0.. 000.. 00 23.0.0.0 0.. 00.0.00 0 00000000060000 .0 00000002001 00 0.00.. 109 high activity a detailed balance of the electronic and steric effects must be matched. Results of hydrogenation of methylphenylacetylene, ethylphenylacetylene, and t-butylphenylacetylene are presented in Tables 23 and 24. In general, hydrogenation rates of these acetylenes are : l-phenyl-l-propyne > phenylacetylene = diphenylacetylene > 1- phenyl-l-butyne, whereas for t-butylphenylacetylene, only less bulky catalysts (R ,S)-79 were able to carry out the hydrogenation to a small extent (11%) after a 12.5 h hydrogenation time. For other more hindered catalysts no hydrogenation uptake was observed. The possible reason may be that the bulky t-butylphenylacetylene prohibits formation of metal-substrate adduct. Thus, the more sterically crowded the substrate, the longer the reaction time. The rate of hydrogenation of diphenylacetylene is about equal to that of phenylacetylene and faster than that of ethylphenylacetylcne, probably due to it’s planar character. The selectivities toward alkene formations for the hydrogenation of diphenylacetylene, 1-phenyl-1- propyne are lower than that of phenylacetylene. An attempt to rationalize the selectivity simply on the basis of substrate bulkiness was unsuccessful (Table 25). Several factors are thought to influence the selectivity and are summarized in section (e). (d). Proposed Mechanism for Hydrogenation of Phenylacetylenes The proposed catalytic cycle is shown in Scheme 9. The first step involves formation of the active metal-substrate adduct 72 by binding of H2 and phenylacetylene to the catalyst precursor 71. It is not clear at this moment whether absorption of H2 or addition of substrate to the catalyst occurs first. The release of HCl (or C12) gas was detected by the color change of litmus paper during the catalysis. A piece of blue litmus paper was attached on the reaction 110 Table 23 Hydrogenation of methylphenylacetylenea Catalyst % propenyl % propyl reaction % conversion selectivity benzene benzene time 59 1 2 88 58 min 100 88.06 60 15 85 1 h 100 85.0c (33)-66 39 61 1 h 100 61 .0c (ES-68 o 100 32 min 100 100.00 (3.51.71 0 100 33 min 100 100.00 (I?,S)-79b 27 73 43 min 100 73.00 58 53 26 30 min 79 672“ 59 19 59 21 min 78 24.4d 60 78 22 16 min 100 78.0‘1 (RS-68 73 27 27 min 100 73.0a 813.725): 10-3 mol substrate, 1x10-5 mol catalyst, 4.5 mL acetone at 80 psi H2 pressure, room temperature b1-dimetl'iylaminomethyl-2-r'-propylthloferroceneyl palladium chloride cselectivity toward propyl benzene dreaction were controlled at 885 psi pressure drop. selectivity toward propenylbenzene 111 Table 24 Hydrogenation of ethylphenylacetylene andt-butylphenylacetylenea substrate catalyst %alkyne % alkene %alkane Rx. time conversion Pheaccsz 58 62.7 34.8 2.5 14 h 37.3 62 39.8 50.7 9.5 21 h 60.2 (3.3-ea 88.8 11.1 0.1 26.5 h 11.2 809 97.6 2.4 0 24 11 2,4 PhCECC4Hg (R,S)-79° 0 89.0 11.0 12.5 h 11.0 58 no reaction 64 no reaction (R,S)-68 no reaction a 3.725x 10‘3 mol substrate, 1x10'5 mol catalyst, 4.5 mL acetone at 80 psi H2 pressure. room temperature '3 1-dimethylaminomethyl-2-methylthioierroceneyl palladium chloride C1dimethylaminomethyl-Z-ilpropylthioterroceneyl palladium chloride 112 Table 25 Hydrogenation of phenylacetylenes by using 58 as catalysta substrate % alkene % alkane Rx. time conversion selectivity PhCECH 88.4 10.3 2 h 98.7 89.6 PhCaCPh 60.0 40.0 1 h 100 60.0 PhCaCCH3 52.8 25.8 30 min 78.6 67.2 PhCECC4H9no Rx. a 3.725x 10'3 mol substrate. 1x10°5 mol catalyst. 4.5 mL acetone at 80 psi H2 pressure, room temperature. selectivity toward alkenes 113 N Cl N\Pd/Cl C \Pd< \ 5/ Cl 5 Cl 71 N C! \ l/ \ / C$)W OH (Eq. 9) O O Hydrogenation of a-acetamidocinnamic acid to N- acetylphenylalanine by in situ catalysts (R,S)-52, (R,S)-53 and (S,R)-84 give ee values at 37.2%, 25.7% and 29.9% , respectively. Hydrogenations of ot-acetamidoacrylic acid and itaconic acid yield somewhat lower ee’s. The higher ee for the former hydrogenation can be rationalized by noting that or-acetamidocinnamic acid is more sterically encumbered than itaconic acid, thus the ct- acetamidocinnamic acid-catalyst adduct possess better diastereoselectivity. A similar observation was found in other catalytic systems with phosphine-based rhodium catalysts.37'140v141 Modifications of both the amino and sulfido substituents or addition of a second sulfido substituent to the unsubstituted Cp ring did not alter the ee significantly. A comparison of the optical yields of these aminosulfide-based catalysts with those of the aminophosphine-based analogues shows that chiral phosphine catalysts do yield better results(entries 7 and 14). The higher ee’s 119 obtained for the phosphine complexes can be attributed to the increased stereorigidity, which is an important factor for achieving high optical yields from the reduction of prochiral substrates.138»141 In the ferrocenyl phosphine catalyst (the chiral phosphine unit possess two phenyl groups), it is suggested that these phenyl groups, as well as the functional group requirements on the substrate, play central roles in the induction of the asymmetry.35vl42.144 For example, attempts to asymmetrically hydrogenate a-ethylstyrene and 2-ethylacrolein were unsuccessful. The former reaction gave 2-phenylbutane with no optical yield and an isomerized product, 2-pheny1-2-butene. The latter hydrogenation gave 69% 2-methylbutyaldehyde with no cc and another isomerized product as shown in Eqs. 10 and 11. The lack of asymmetric induction in these two cases shows the requisite of a carbonyl group three atoms away to the double bond to cooperatively (with the double bond) bond to the catalyst to form a stereorigid intermediate and thus induce high asymmetry. (Eq.10) 120 + H2 "' + \ (EQ- 11) 69 °/o 22 % Attempts to employ ferrocenyl palladium complexes as catalysts in the reduction of a-acetamidoacrylic and a-acetamido- cinnamic acid was not successful. Yet, complexes (R,S)-68 and (R ,S)-70 do hydrogenate itaconic acid, though the optical yields were low. It gives 4.7% cc in one case and no enantiomeric excess at all in other case (Table 26, entries 11 and 12). It is apparent that the course of hydrogenation should be different from that of the rhodium catalytic system since there are not as many coordination sites available as in the case of rhodium catalyst. Perhaps the reaction pathways will be similar to the reduction of the conjugated double bonds where chemoselective and regioselective reactions dominate. In situ ferrocenyl nickel complexes were also tested in the hydrogenation of itaconic acid (entry. 13). No hydrogenation uptake was observed after one day, presumably because no vacant coordination site is available for effective substrate-catalyst adduct formation for the further hydrogenations. Proposed Mechanism Based on the previous mechanistic study of asymmetric hydrogenation of prochiral aminoacids catalyzed by cationic rhodium ferrocenylphosphine complexes”, the active catalytic species is probably [(N-S)Rh(solvent)2]+, where (N-S) stands for ferrocenylamine sulfide ligands bonded to rhodium through N and S atoms. The hydrogenation then proceeds as sketched in Scheme 10. Ph Mr 1 :__£;/~H 121 Ph COOH + Nt-ICOCH3 1:1 > ‘ k-i ' COOH NHCOCH3 [0112911 W + -COOH k3 1. Ph '1 + C/W Rh' Agog... ——O NH ee§K ‘ k2 [“2] Ph '+ Scheme 10 Proposed mechanism for asymmetric hydrogenation 122 According to this mechanism, substrate was added to the rhodium solvate to form a square planar intermediate 88 in which the substrate bonded to rhodium through the acylcarbonyl and the olefin.23»45'143 The cis-addition of hydrogen to the catalyst then occurred with the metal center rearranging to form an octahedral intermediate 89. Insertion of a hydrogen atom into the substrate then proceeded in steps (3) and (4) to form the aminoacid and to continue the catalytic cycle. However, the other plausible catalytic pathway via a hydride intermediate [(N-S)Rh(H)2(solvent)x]+ rather than the simple solvate cannot be ruled out.23i50 Concluding Remarks Several factors may influence the enantioselectivity of an asymmetric synthesis, such as the catalyst stereorigidity, substrate structures, solvents, temperature, and hydrogenation pressures. For the hydrogenation of prochiral aminoacids the stereorigidity and structures of substrates play the center role in the induction of asymmetry. More stereorigid chelating phosphine-based rhodium catalysts induce higher ee than the sulfide analogues. Furthermore, the effective substrates are characterized by the presence of a neighboring polar binding site (an acylamino substituent) as well as the reactive olefin site. These two binding sites can affect the anchoring of the substrate to the catalyst through chelation, thus better stereoselectivity can be achieved. Though, to date, the choice of chiral ligands (as well as the asymmetric catalysts) is still empirical. The opportunities, via molecular engineering, to achieve high optical yield are unlimited. This type of chemistry should remain a very fruitful frontier full of promise. 123 D. Asymmetric Grignard Cross-Coupling Reaction The asymmetric cross-coupling reaction of 1-chloroethyl- benzene with allylmagnesium chloride using group 10 metal ferrocenylsulfide catalysts has been studied in this laboratory. 125.127 It was found that ferrocenylsulfide catalysts with thioether substituents on both cyclopentadiene rings gave better enantiomeric excess than the monosubstituted analogues. Increasing the steric crowdedness of the thioether substituents also increases the optical yield. As an extension of this work, we intended to investigate the efficacy of asymmetric synthesis upon replacement of the dimethylaminc substituent with the more bulky diethylamine and di-n-propylamine groups. The Grignard cross-coupling reaction shown in Eq. 12 was studied by using different palladium ferrocenylamine sulfide complexes. The chemical yields of all reactions exceeded 90%, and optical yields varied depending on the catalysts used. The cross- coupling product, 4-phenyl-l-pentene, was oxidized with potassium permanganate and sodium periodate as reported previously.”5 The optical rotation of the resulting acid is strongly affected by small quantities of impurities; therefore it is usually converted to the methyl ester (Eq. 13) and the optical yields were determined by 1H NMR spectroscopy with the chiral shift reagent, Eu(dcm)3.145 _X MQCI ———> (Eq. 12) Ph + W Ph \ 32 124 CH . Ph \ = (Eq.13) MeOH.TsOH Ph 32 33 As shown in Fig. 20 for the 1H NMR spectrum of methyl-3- phenylbutyrate, the methyl ester proton signal splits into two singlets for the two diastereomers. Integration of these two singlets reflects directly the optical yield of the coupling product. The procedure was used previously by Kumada and co-workers, who assigned the higher field signal for the S enantiomer of methyl-3- phenylpropionate.147 Increasing the shift reagent concentration deshielded the chemical shift 8 of the methyl ester proton signal and increased the enantiomeric shift difference AA 8. The best concentrations of the chiral shift reagent and the substrate were 0.27 M and 0.5 M in CDCl3 respectively, where the AA5 was large enough for the integration of the appropriate signals. Results of this asymmetric synthesis are tabulated in Table 27. Modifying the sulfide substituents did not influence the optical yields greatly. However, by replacing the dimethylamine group with diethylamine and dim-propylamine, the ee decreased from 26 to 13.4 and 5.8 (entries 7, 1 and 2). Furthermore, unlike the catalytic system with the dimethylaminc group where the absolute configuration of the coupling product was dependent on the configuration of the catalyst used, the (R,S)-catalysts gave S «~33, while the (S,R)-catalysts gave R -33. In the case of diethylamine and di-n-propylamine substituents, the coupling reaction gave only R product regardless of the catalyst configuration. These observations were also found in the ferrocenylphosphine-based nickel catalytic system PPFA/NiCl2.75 Obviously, the steric bulkiness of the amino substituent has a powerful effect on the stereoselectivity. Replacing the chloro functional group with a bromo group in the substrate didn’t change the optical yield significantly. 125 nAEocvam 0.0080. 0.00 .0000 .0 0000020 00. 0. 0.0.0.3 3000030856. 000 -E. .0 0.8000 .022 z. .00 050.0 .00.- 0 . 0 0 0 0 0 . 0 3.3. 1031-0 .0 126 Table 27 Asymmetric Gringard cross-coupling of chloroethylbenzene with allylmagnesium chloride by new chiral ferrocenylamine sulfide catalystsal catalyst °/o optical yield Cont. (S,fl)-66 (R=Et,R'=Me,X=Cl) 13.4 R (33)-67 (R=n-Pr,R'=Me) 5.8 R (ES-69 (R=n—Pr,R'=Et) 1 1 .8 R (H,S)-7O (R=Et,R'=i-Pr) 10.0 R (R,S)-71 (R=n-Pr,R'=i-Pr) 12.8 R (3.3-71b (X=Br) 8.6 R (33)-79° (R=Me,R'=Me,X=CI) 26.0 R (53)-83° (R=Me,R'=i-Pr) 31.0 R a 10 mmol 1-phenylethylchloride, 20 mmol allylmagnesium chloride, 36 h at room temperature b using bromoethylbenzene as halide source 0 Bet. 124 127 It is not clear at this moment why increasing the steric bulkiness of the amino substituent should reduce the optical yield. However, based on the available data, the amino group on the ferrocenyl ligand is most important for high stereoselectivity and the nitrogen atom environment exerts a strong effect on the asymmetric induction. APPENDIX 128 m. c." t." o.m pr bl r, ,P t—.: .r; .--s: rim. :Ll.-ri tr, r _ t. r- F -.l _l r .l. Eu 0.2 mm ..m um B a 52.8% 022 1. ~15. 08 .5 2:9... Ina m.m cm. m.m o.v -b|.Pll_l.LliLllLl|rli|Pll.r-ir p...rll_.iri P r- rl_, 2?-Jfildl/ .uiv .r » birth? r u. lr: Fri. 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L I'll" .|.|.I..- P b I D b Sam. :m 3?? L kLL L AFL0+J ' T———F__hmfi. « d .00. 00.0... ...0 ..0 ...0 .../00 W20 @ - .\ xbmvv .1 0%.: .. 0......“ on 3.0.08 .0 E2600... 000.2 BI .00 0.00... T0...... 3.... 3.... .-,-1,-i««-.«l.33_. !« ..l'n.‘ Il!n|‘.nl| 174 000?... 000 09. 000 no 00.0.08 .0 E00300 000.... m<0 .00 0.00... Dam sad -«N m... a ...mu -«iisL 3.6.5 .8388 ,8 8.53% mums. m ‘ tll‘Ls ilk-I... 11.39%.-- p .3 H v.3 5 w. L k [3,... am... .365 m. ...m ..m ...: A Q 8,2, I on _ m . z s , \va c o 5...... ... . _ n\ .. ~ “4— — sw—knm. AI.” ‘ ..-...i._........# L .3 -. .2.: REFERENCES ll. 12. REFERENCES . Kagan, H. B. Bull. Soc. Chim. Fr. 1988,35, 846. . Koenig, K. E. Asymmetric Synthesis ; Morrison J. D. Ed. ; Academic; New York, 1984, Vol 5 , Pl. . (a). Kagan, H. B. and Fiaud, J. C. Topics in Stereochemistry, Ed by Eliel E. L. and Allinger, N. L., Wiley-Interscience, New York 1978, Vol. 10 P. 175. (b). Bosnich, B. Asymmetric Catalysis Kluwer Academic Publishers, Boston, MA., 1986 . 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