PLACE IN RETURN BOX to man this chockout from your mood. TO AVOID FINES return on or beta. due due. DATE DUE DATE DUE DATE DUE MSU Is An Affirmative Action/Equal Opportunity Institution NEW FERROCENYL THIO AND ETHERS LIGANDS. PREPARATION, CHARACTERIZATION, AND THEIR PALLADIUM(II) AND PLATINUM(II) COMPLEXES AS CATALYSTS FOR SELECTIVE HYDROGENATION. BY Chung-Kung Lai A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Chemistry 1988 ABSTRACT NEW FERROCENYL THIO AND SELENO ETHER LIGANDS. PREPARATION, CHARACTERIZATION, AND THEIR PALLADIUM(II) AND PLATINUM(II) COMPLEXES AS CATALYSIS FOR SELECTIVE HYDROGENATION. BY Chung-Kung Lai A series of previously unknown ferrocenyl thioethers (C5H3-l-CH2NMe2-2-SR)Fe(C5H4-SR), R= Me, Et, g-Pr, i—Pr, g- Bu, g-Bu, g-Bu, i—Pentyl, Ph, Bz, 4-Tolyl and 4-Cl-Ph, have been prepared from the appropriate ferrocene precursors via dilithiation and reactions with RS-SR. The following techniques were used for characterization: 1H, 13C NMR, IR, MS and elemental analysis. The ferrocenylsulfide derivatives readily chelate with palladium(II) and platinum(II) chlorides to form the heterobimetallic complexes, (C5H3-1- CHZNMez-Z-SR)Fe(C5H4-SR)PdC12, R= Me, Et, 3-Pr, i-Pr, Ph, Bz, 4-Tolyl, 4-Cl-Ph and (C5H3-l-CH2NMe2-2-SR)Fe(C5H4-SR)- ptc12, R= Me, Ph, Bz, 4-Toly1, 4-C1-Ph. la NMR spectra were obtained for these complexes, IR, MS, and elemental analysis data were also presented. The X-ray crystal structure of (C5H3-1-CH2NMe2-2-SCH3)Fe(C5H4-SCH3)PdClz was also studied. The chiral ferrocenylthioethers and selenoethers, (B,§)-(C5H3-l-CHMeNMe2-2-SR)Fe(C5H4-SR), R= Me, Et, n-Pr, ;- Pr, g-Bu, s-Bu, t-Bu, i-Pentyl, Ph, Bz, 4-Tolyl, 4-Cl-Ph, (B,§)-(C5H3-1-CHMeNMe2-2-SeR)Fe(CSH4-SeR), R= Me, Ph, 4—Cl- Ph and (B,§)-(C5H3-1-CHMeNMe2-2-SeR)Fe(C5H5), R= Me, Ph, 4- Cl-Ph also have been prepared and their palladium(II) and platinum(II) complexes, (3,§)-(C5H3-1-CHMeNMe2-2-SR)Fe(C5H4- SR)PdC12, R= Me, Et, g-Pr, i-Pr, Ph, Bz, 4-Tolyl, 4-Cl-Ph, (B,§)-(C5H3-1-CHMeNMe2-2-SR)Fe(C5H4-SR)PtClZ, R= Me, Ph, Bz, 4-Tolyl, 4-Cl-Ph, and (3,§)-(C5H3-1-CHMeNMe2-2-SeR)Fe(C5H4- SeR), R= Me, Ph, 4-Cl-Ph were prepared. The following techniques were used for the characterization: 1H, 13C NMR, IR, MS, and elemental analysis. The palladium(II) ferrocenylsulfide complexes are good selective homogeneous and heterogeneous hydrogenation catalysts for reduction of dienes to monoenes at room temperature, and possible mechanisms are discussed in detail. 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. E. LeGoff for many helpful discussions and all the group members, A. A. Naiini, A. Hussein and C. H. Wang for the friendship. Finally, I wish to express my deepest appreciation and thanks to my parents for their love, inspiration and understanding. ii TABLE OF CONTENTS PAGE LIST OF TABLES ..... ............ .. .................... . ix LIST OF FIGURES .............. ...... ................... xi I. INTRODUCTION ... .......... . ..... ...... ...... ........ 2 II. EXPERIMENTAL .................. ....... ............. 21 A. PREPARATION OF LIGANDS ......OOOOOOO00.000.00.00... 22 l-Dimethylaminomethyl-Z-1’-bis(methylthio)- ferrocene ...... .. ........ ............. ........... 22 l-Dimethylaminomethyl-z-1'-bis(ethylthio)- ferrocene ............................. ........... 24 1-Diemthylaminomethyl-2-l’-bis[(n-Pr)thio]- ferrocene ............................... ..... .... 26 l-Dimethylaminomethyl-2-1'-bis[(i-Pr)thio]- ferrocene ... ...................... . .............. 27 1-Dimethylaminomethyl-2-l’-bis[(n-Bu)thio]- ferrocene ........................................ 29 l-Dimethylaminomethyl-z-1’-bis[(s—Bu)thio]- ferrocene ........................................ 30 1-Dimethylaminomethyl-2él’-bis[(t-Bu)thio]- ferrocene ........ ..... ..................... ...... 32 1-Dimethylaminomethyl-2-1’-bis[(i-pentyl)- thio]ferrocene ........ ............ ............... 33 1-Dimethylaminomethyl-2-1'-bis(phenylthio)- ferrocene OO.......OOOOOOOOOOOOOOOOOOOOO0.....0... 35 l-Dimethylaminomethyl-z-1’-bis(benzylthio)- ferrocene ..... . .................................. 37 1-Dimethylaminomethyl-2-l’-bis[(4-tolyl)- thio]ferrocene ...................... ............. 38 iii l-Dimethylaminomethyl-Z—1’-bis[(4-cholo— phenyl)thio]ferrocene ............................ 40 B-l-(Dimethylamino)-ethylferrocene[(3)-1] ......... 42 (3,§)-l-(l-Dimethylaminoethyl)-2-(methyl- seleno)ferrocene ..................... ............ 43 (3,§)-1-(l-Dimethylaminoethyl)-2-(phenyl- seleno)ferrocene .................. ............... 44 (R,§)-l-(l-Dimethylaminoethyl)-2-[(4-Cl-Ph)— seleno]ferrocene ......... .. ..... . ................ 46 (3,§)-1-(1-Dimethylaminoethyl)-2-1'-bis(methyl- thio)ferrocene ....... ............ ......... .. ..... 48 (R,§)-l-(1-Dimethylaminoethyl)-2-1’-bis(ethyl- thio)ferrocene ............ ....... ................ 49 (3,§)-l-(l-Dimethylaminoethyl)-2-l’-bis[(n-propyl)- thio]ferrocene ................................... 51 (3,§)-l-(l-Dimethylaminoethyl)-2-1'-bis[(i-propyl)— thio]ferrocene ................................... 52 (B,§)-l-(1-Dimethylaminoethyl)-2-1’-bis[(n-butyl)- thio]ferrocene ................................... 54 (B,§)-l-(l-Dimethylaminoethyl)—2-1'-bis[(s-butyl)- thio]ferrocene ........... . ....................... 56 (B,§)~1-(1-Dimethylaminoethyl)-2-1’-bis[(t-butyl)- thio]ferrocene ............. . .................... . 57 (R,§)-l-(l-Dimethylaminoethyl)-2-l’-bis[(i-pentyl)- thio]ferrocene ................................... 59 (B,§)-1-(1-Dimethylaminoethy1)-2-1’-bis(phenyl- thio)ferrocene ........... . ....................... 60 (R,§)-l-(1—Dimethylaminoethyl)-2-1’-bis(benzyl- thio)ferrocene .................. ............ ..... 62 (B,§)-1-(1-Dimethylaminoethyl)-2-1’-bis[(4-tolyl)- thio]ferrocene ..... . ............................. 64 (g,§)-1-(1-Dimethylaminoethyl)-2-1’-bis[(4-Cl-Ph)— thio]ferrocene ................................... 65 (B,§)-l-(1-Dimethylaminoethyl)-2-1’-bis(methyl- seleno)ferrocene ............ . .................... 67 iv (B,§)-1-(1-Dimethylaminoethyl)-2-1'-bis(phenyl- seleno)ferrocene ................................. 69 (R,§)-1-(1-Dimethylaminoethyl)-2-1’-bis[(4-Cl-Ph)- seleno]ferrocene ................................. 70 B. PREPARATION OF METAL COMPLEXES .......... ......... 73 1-Dimethylaminomethyl-2-1'-bis(methylthio)- ferrocene palladium(II) chloride ................ 73 1-Dimethylaminomethyl-2-1'-bis(ethylthio)- ferrocene palladium(II) chloride ....... ......... 74 1-Dimethylaminomethyl-2-1’-bis[(n-Pr)thio]- ferrocene palladium(II) chloride ..... ........... 75 1-Dimethylaminomethyl-2-l'—bis[(i-Pr)thio)- ferrocene palladium(II) chloride ......... ....... 75 1-Dimethylaminomethyl-2-1’-bis(phenylthio)- ferrocene palladium(II) chloride ................ 76 1-Dimethylaminomethyl-2-1'-bis(benzylthio)- ferrocene palladium(II) chloride ......... ....... 77 1-Dimethylaminomethyl-2-l'-bis[(4-tolyl)thio]- ferrocene palladium(II) chloride ..... ........... 77 l-Dimethylaminomethyl-Z-l’-bis[(4-Cl-Ph)thio]- ferrocene palladium(II) chloride ..... . .......... 78 l-Dimethylaminomethyl-Z—1’-bis(methylthio)- ferrocene platinum(II) chloride .......... ....... 79 l-Dimethylaminomethyl-Z-1’-bis(phenylthio)- ferrocene platinum(II) chloride ........ ......... 80 1-Dimethylaminomethyl-2-l’-bis(benzylthio)- ferrocene platinum(II) chloride .......... ....... 80 1-Dimethylaminomethyl-2-1’-bis[(4-tolyl)thio]- ferrocene platinum(II) chloride ....... .......... 81 1-Dimethylaminomethyl-2-1’-bis[(4-Cl-Ph)thio]- ferrocene platinum(II) chloride ............ ..... 81 (3,5)-1-(1-Dimethylaminoethyl)-2-(methylseleno)- ferrocene palladium(II) chloride ..... ........... 82 (R,§)-1-(l-Dimethylaminoethyl)-2-(phenylseleno)- ferrocene palladium(II) chloride ...... .......... 83 (R,§)-1-(1-Dimethylaminoethyl)-2-[(4-Cl-Ph)- seleno]ferrocene palladium(II) chloride ......... 84 (3,§)-1-(l-Dimethylaminoethyl)—2-1’-bis(methy1- thio)ferrocene palladium(II) chloride ........... 84 (3,5)-1-(l-Dimethylaminoethyl)-2-l'-bis(ethyl- thio)ferrocene palladium(II) chloride ...... ..... 85 (3,§)-l-(1-Dimethylaminoethyl)-2-1’-bis[(n-Pr)- thio]ferrocene palladium(II) chloride .... ....... 85 (3,§)-1-(1-Dimethylaminoethyl)-2-l'-bis[(i-Pr)- thio]ferrocene palladium(II) chloride ........... 86 (B,§)~1-(1-Dimethylaminoethyl)-2-1'-bis(phenyl- thio)ferrocene palladium(II) chloride ........... 87 (R,§)-1-(l—Dimethylaminoethyl)-2-1’-bis(benzyl- thio)ferrocene palladium(II) chloride ........... 87 (B,§)-1-(1-Dimethylaminoethyl)-2-1’-bis[(4-toly1)- thio]ferrocene palladium(II) chloride ........... 88 (B,§)~1-(1-Dimethylaminoethyl)-2-1’-bis[(4-Cl-Ph)- thio]ferrocene palladium(II) chloride ..... ...... 89 (3,5)-1-(1-Dimethylaminoethyl)-2-1’-bis(methyl- seleno)ferrocene palladium(II) chloride ......... 90 (R,§)-1-(1-Dimethylaminoethyl)-2-1’-bis(phenyl- seleno)ferrocene palladium(II) chloride .... ..... 90 (B,§)-1-(1-Dimethylaminoethyl)-2-1'-bis[(4-Cl-Ph)- seleno] ferrocene palladium(II) chloride ........ 91 (B,§)-1-(1-Dimethylaminoethyl)-2-1'-bis(methyl- thio)ferrocene platinum(II) chloride ............ 91 (R,§)-1-(1-Dimethylaminoethyl)-2-1’-bis(phenyl- thio)ferrocene platinum(II) chloride ............ 92 (g,§)-l-(1-Dimethylaminoethyl)-2-1’-bis(benzyl- thio)ferrocene platinum(II) chloride ............ 93 (3,§)-1-(l-Dimethylaminoethyl)-2-1'-bis[(4-tolyl)- thio]ferrocene platinum(II) chloride ............ 93 (B,§)-l-(l-Diemthylaminoethyl)-2-1’-bis[(4-Cl-Ph)- thio]ferrocene platinum(II) chloride ............ 94 vi (3,5)-1-(1-Dimethylaminoethyl)-2—[(4-Cl-Ph)- seleno]ferrocene palladium(II) chloride ......... 84 (3,§)~1-(l-Dimethylaminoethyl)~2-1’-bis(methyl- thio)ferrocene palladium(II) chloride ........... 84 (B,§)-1-(l-Dimethylaminoethyl)-2-1'-bis(ethyl- thio)ferrocene palladium(II) chloride .. ......... 85 (3,§)-l-(1-Dimethylaminoethyl)-2-1'-bis[(n-Pr)- thio]ferrocene palladium(II) chloride ..... ...... 85 (B,§)-l-(l-Dimethylaminoethyl)-2-1’-bis[(i-Pr)- thio]ferrocene palladium(II) chloride ........... 86 (B,§)-1-(l-Dimethylaminoethyl)—2-1'-bis(phenyl- thio)ferrocene palladium(II) chloride ........... 87 (B,§)-1-(l-Dimethylaminoethyl)-2-1’-bis(benzyl- thio)ferrocene palladium(II) chloride ........... 87 (3,5)-l-(1-Dimethylaminoethyl)-2-1’-bis[(4-tolyl)- thio]ferrocene palladium(II) chloride .. ......... 88 (3,5)-1-(1-Dimethylaminoethyl)-2-1’-bis[(4-Cl-Ph)- thio]ferrocene palladium(II) chloride . .......... 89 (B,§)-1-(l-Dimethylaminoethyl)-2-1'-bis(methyl- seleno)ferrocene palladium(II) chloride ......... 9o (B,§)-l-(l-Dimethylaminoethyl)-2-1’-bis(phenyl- seleno)ferrocene palladium(II) chloride ......... 90 (3,5)-1-(1-Dimethylaminoethyl)-2-1'-bis[(4-c1-ph)- seleno] ferrocene palladium(II) chloride .. ...... 91 (B,§)-1-(1-Dimethylaminoethyl)-2-1’-bis(methyl- thio)ferrocene platinum(II) chloride ...... . ..... 91 (B,§)-1-(1-Dimethylaminoethyl)-2-1’-bis(phenyl- thio)ferrocene platinum(II) chloride ............ 92 (B,§)-1-(1-Dimethylaminoethy1)-2-1’-bis(benzyl- thio)ferrocene platinum(II) chloride ............ 93 (B,§)-1-(1-Dimethylaminoethyl)-2-1'-bis[(4-tolyl)- thio]ferrocene platinum(II) chloride ....... ..... 93 (B,§)-1-(l-Diemthylaminoethyl)-2—1’-bis[(4-c1-ph)- thio]ferrocene platinum(II) chloride ............ 94 vi C. III. CATALYTIC APPLICATIONS OF COMPLEXES . ....... . ..... 95 a. Selective Hydrogenation of Conjugated 1,3-Cyclo- octadiene to Cyclooctene with Catalysts 55-55 and 51-14 in Organic Solvents ................. 95 b. Solvent-Effects Studies in Hyrdogenation of 1,3-Cyclooctadiene to Cyclooctene with catalystSflandu..OOOOOOOOOOOOOOOOOOOOO.... 96 c. Additive-Effects Studies in Hydrogenation of 1,3-Cyclooctadiene to Cyclooctene with Catalyst 11 ...... . ......... . ...... .... ................. 96 d. Selective Hydrogenation of 1,3-Cyclohexadiene to Cyclohexene with Catalysts 55, 55, 1; and 11 ........................................ 96 RESULTS AND DISCUSSION ........................... 98 (C5H3-1-CH2NMe2-2-SR)Fe(C H4-SR) (R=Me, Et, n—Pr, i-Pr, n— u, s-Bu, t-Bu, i—Pentyl, Ph, Bz, 4-Tolyl, 4-Cl-Ph) .............. 98 (1) (B,§)-(CH 3-1-CHNMe -2-SR)Fe(C5H4 -SR), (R=Me, E , 3n-Pr, ;- r, n- Bu, 5— Bu, t- -Bu, i-Pentyl, Ph, Bz, 4-Tolyl, 4-Cl-Ph) .. ....... 113 (2) (3,§)-(c H3-l-CHMeNMe2-2- SeR)Fe(C5H4-SeR), (R=Me, P , 4-Cl-Ph), and (3, §)- (c5 H -1- CHMe- Palladium Complexes of (C5H3-1-CH2NMe2-2-SR)Fe- -SR), (R=Me, Et, n-Pr, i-Pr, Ph, Bz, fiioiyl, 4-Cl- -Ph), and Platnium Complexes of (CSH -1-CH NMe 2-2-SR)Fe(C5H4-SR), (R=Me, Ph, Bz, 2-Tolyi, 4-Cl- -Ph) ......... ..... . ............ 132 Palladium Complexes of (3,5)-(C5H3-1-CHMeNMe2-2- SR)Fe(C5H4-SR), (R=Me, Et, n-Pr, i-Pr, Ph, Bz, 4-Tolyl, 4-Cl- -Ph), Platinum Complexes of (3,§)-(CH -1-CHMeNMe2-2-SR)Fe(C5 H -SR), (R=Me, Ph, Bz, 2- Tolyl, 4-Cl- -Ph), and Paliadium Complexes of (3, §)- (c H4-l-CHMeNMe2-SeR)Fe(C5H4-SeR), (R=Me, Ph, 4-C1- Ph .................................... 139 x-ray structure studies of l-dimethylaminomethyl- 2-1’-bis(methy1thio)ferrocene palladium dichloride (5;) ......... ...... ............... .............. 145 Catalytic Application Of Complexes ..... . ........ 147 (a) Selective Hydrogenation of Conjugated 1,3- Cyclooctadiene to Cyclooctene ............... 149 vii (b) Selective Hydrogenation of Conjugated 1,3- Cyclohexadiene to Cyclohexene .......... ..... 164 IV. APPENDIX .... .................................... 168 V. REFERENCES .. ......... .................... 228 viii LIST OF TABLES TABLE PAGE 1. 10. 11. Optically active ligands most used for asymmetric catalytic reaction ...................., 12 Metals used in homogeneous catalytic asymmetric reaction in combination with different chiral ligands ........ . ........................... 14 250 HMZ 13 NMR data for (C5H3-l-CH NMez-Z-SR)- Fe(C5H4-SR) in CDCl3/TMS, 5 ppm, a room temperature... ..... ......OOCOOCOOOCOOCCOC ........ 101 13c NMR data for (c H3-1-CH2NMe2-2-SR)Fe- (C5H4-SR) in CD3COC 3/TMS, 5 ppm, at room temperature ................................ ..... . 107 250 KHZ 1H NMR data for (B,5)-(C5H3-CHMeNMe2- 2-SR)Fe(C5H4-SR) in CDCl3/TMS, 5 ppm, at room temperature ..... ..... . ...... ............ ......... 116 13c NMR data for (3,5)-(C5H3-l-CHMeNMe2-2-SR) Fe(C5H4-SR) in CD3COCD3/TMS, 5 ppm, at room temperature .................... . ................. 121 250 MHz 13 NMR data for (3,§)-(CSH3-1-CH2NMe2- 2-SeR)Fe(C5H4-SeR) in CDCl3/TMS, 5 ppm, at room temperature ......OOCCCCOOO......OOOCCCOCOOCCOOOOO 127 250 HMz la NMR data for (C5H3-l-CH2NMe2-2-SeR) Fe(C5H4-SeR) in CDCl3/TMS, 5 ppm, at room temperature ... ............ . ...................... 128 13c NMR data for (3,§)-(c H -l-CHMeNMe -2-SeR) Fe(C5H4-SeR) in CD3COCD3/TMg, 5 ppm, a room temperature eeeeeeeeee eeeee eeeee‘eeeeeeeeee eeeeeee 130 13c NMR data for (c H3-l-CHMeNMe2-2-SeR)Fe- (C5H4-SeR)in CD3COC 3/TMS, 5»ppm, at room temperature 0....O..........OOOOIOOOOOOOOOOOOO.... 131 250 HMz 1H NMR data for complexes (C H3-1- CHZNMez-Z-SR)Fe(C5H4-SR)PdClz, in CD 13/TMS, 5 ppm, at room temperature ............... ........ 133 ix 12. 13. 14. 15. 16. 17. 18. 19. 250 HMz 1H NMR data for complexes (3,5)-(C5H - 1-CHMeNMe2-2-SR)Fe(C5H4-SR)PdC12 in CDCl3/TMg, 5 ppm, at room temperature ....... ....... . ........ 250 HMz 1H NMR data for complexes (3,5)-(C H -1- CHMeNMez-Z-SeR)Fe(C5H4-SeR)PdClz in CDCl3/TMS, 6 ppm, at room temperature .... ................... Hydrogenation of 1,3-Cyclooctadiene - Effect of Catalysts with (55-55) ........... ......... . ...... Hydrogenation of 1,3-Cyclooctadiene - Effect of Solvents with (55) as Catalyst ... ..... . .......... Hydrogenation of 1,3-Cyclooctadiene - Effect of Catalysts with (51-15) .. ..... .................... Hydrogenation of 1,3-Cyclooctadiene - Effect of Solvents with (15) as Catalyst ................... Hydrogenation of 1,3-Cyclooctadiene - Effect of Additives with (15) as Catalyst .................. Hydrogenation of 1,3-Cyclohexadiene - Effect of Catalysts with (55, 55, 11, 15) ..... ............. 140 141 153 155 156 158 LIST OF FIGURES FIGURE PAGE 1. Synthesis routes for ferrocenylsulfide compounds, 21-52_.......................... ....... 100 2. The 250HMz 13 NMR spectrum of 25, R= n-Butyl ..... 104 3. The 13C NMR spectrum of 51, R= 4-Tolyl .. ......... 109 4. Synthesis routes for chiral ferrocenylsulfide compounds, 55-41 ........... ......... . ............ 114 5. The 250 HMz 1H NMR spectrum of 55, R= 5-Pr ....... 119 6. The 13C NMR spectrum of 41, R= Phenyl ............ 123 10. 11. 12. 13. 14. 15. 16. 17. The 1H NMR spectra of 51 and its palladium complex, 51, R= Phenyl ............ ...... . ........ 136 The 1H NMR spectra of 15 and its palladium complex, 1;, R= 4-Tolyl .......... ................ 142 Olefinic region of 250 HMz 1H NMR of 1,3-cyclo- octadiene (top), the mixture of 1,3-cyclooctadiene and cyclooctene (middle) and cyclooctene ......... 151 Possible mechanisms of the homogeneous selective hydrogenation of 1,3-cyclooctadiene through a four-coordination intermediate, Fc-; 2,1’-dialkyl- thioferrocenyl ................................... 161 1H NMR spectrum of 21, R= Me ..................... 168 13C NMR spectrum of 2;, R= Me . ........... ... ..... 169 1H NMR spectrum of 52, R= Et ..................... 170 13C NMR spectrum of 2;, R= Et .................... 171 1H NMR spectrum of 55, R= g-Pr ......... ........ .. 172 13C NMR spectrum of 25, R= g-Pr .................. 173 1H NMR spectrum of 55, R= i-Pr ................... 174 xi 18. 19. 20. 21. 22. 23. _24. 25. 26. 27. 28. 29. 3o. 31. 32. 33. 34. 35. 36. 37. 38. 39. 4o. 41. 42. 43. 44. 13C NMR spectrum of 24, R= i-Pr ..... ........ ..... 1H NMR spectrum of 25, R= g-Butyl ................ 13C NMR spectrum of 25, R= n-Butyl ............... 1H NMR spectrum of 25, R= g-Butyl ................ 13C NMR spectrum of 25, R= g-Butyl ...... ......... 1H NMR spectrum of 25, R= 1—Pentyl ............... 13C NMR spectrum of 25, R= i-Pentyl .............. 1H NMR spectrum of 25, R= Phenyl ................. 13C NMR spectrum of 25, R= Phenyl ........ . ....... 1H NMR spectrum of 55, R= Benzyl . ...... . ......... 13C NMR spectrum of 55, R= Benzyl ................ 1H NMR spectrum of 51, R= 4-Tolyl . ............... 13C NMR spectrum of 51, R= 4-Tolyl .............. . 1H NMR spectrum of 52, R= 4-Cl-Ph ....... ......... 13C NMR spectrum of 52, R= 4-Cl-Ph ............... 1H NMR spectrum of 54, R= Phenyl ................. 13C NMR spectrum of 54, R= Phenyl ................ 1H NMR spectrum of 55, R= 4-Cl-Ph ................ 13C NMR spectrum of 55, R= 4-Cl-Ph ............... 1H NMR spectrum of 55, R= Me .. ..... . ..... ........ 13C NMR spectrum of 55, R= Me .. ........ ... ....... 1H NMR spectrum of 51, R= Et ... ..... ....... ...... 13C NMR spectrum of 51, R= Et ... ................ . 1H NMR spectrum of 55, R= n-Pr . .................. 13C NMR spectrum of 55, R= g-Pr .. .......... ...... 1H NMR spectrum of 55, R= i—Pr ................... 13C NMR spectrum of 55, R= i—Pr . ........... ...... xii 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 1H NMR spectrum of 45, R= g-Butyl ................ 202 13c NMR spectrum of 45, R= g-Butyl ............. .. 203 1H NMR spectrum of 41, R= 5-Butyl ................ 204 13C NMR spectrum of 41, R= §-Butyl ..... .......... 205 1H NMR spectrum of 42, R= 5-Butyl . ..... . ......... 206 13C NMR spectrum of 42, R= 5-Butyl ....a .......... 207 1H NMR spectrum of 45, R= i-Pentyl . .............. 208 13C NMR spectrum of 45, R= i-Pentyl .............. 209 1H NMR spectrum of 44, R= Phenyl ................. 210 13C NMR spectrum of 44, R= Phenyl ................ 211 1H NMR spectrum of 45, R= Benzyl . ................ 212 13C NMR spectrum of 45, R= Benzyl ................ 213 1H NMR spectrum of 45, R= 4-Tolyl ................ 214 13C NMR spectrum of 45, R= 4-Tolyl ....... . ...... . 215 1H NMR spectrum of 41, R= 4-Cl-Ph ................ 216 13c NMR spectrum of 41, R= 4-Cl-Ph ............... 217 13C NMR spectrum of 45, R= Me ..... ..... ... ...... . 218 13C NMR spectrum of 45, R= Phenyl ................ 219 1H NMR spectrum of 55, R= 4-Cl-Ph ................ 220 13C NMR spectrum of 55, R= 4-Cl-Ph ............... 221 1H NMR spectrum of 55, R= Phenyl ................. 222 1H NMR spectrum of 51, R= 4-Tolyl . ............... 223 1H NMR spectrum of 55, R= 4-Cl-Ph ................ 224 1H NMR spectrum of 11, R= Phenyl ................. 225 1H NMR spectrum of 15, R= 4-Tolyl ................ 226 1H NMR spectrum of 14, R= 4-Cl-Ph ................ 227 xiii NEW FERROCENYL THIO AND SELENO ETHER LIGANDS. PREPARATION, CHARACTERIZATION, AND THEIR PALLADIUM(II) AND PLATINUM(II) COMPLEXES AS CATALYSIS FOR SELECTIVE HYDROGENATION. INTRODUCTION There has been intense interest and activity in asymmetric synthesis catalyzed by transition metal complexes with chiral ligands. 1'2 Although Emil Fischer mentioned asymmetric synthesis as early as 1894 3 and Markwald 4 defined it ten years later, it was not until the mid-sixties that two developments offering very attractive approaches toward making such catalysts occured. The first catalyst was 5 and coworker, chlorotris- introduced by Wilkinson (triphenylphosphine)rhodium, 1 [RhCl(PPh3)3], and it exhibited amazing properties as a soluble hydrogenation catalyst for unhindered olefins. H 2 CH2=CH2 + RhCl (PPhB) 3 --------------- > CH3-CH3 1 Homogeneous catalysts had been reported before, but this was the first one that compared in rates with the well- known heterogeneous counterparts. The other development was the discovery by Horner 6 in 1968 of methods for preparing optically active phosphine. The basic strategy was to replace the triphenylphosphine in Wilkinson's catalyst with a known asymmetric phosphine and hydrogenate a prochiral olefin. Hz RCH=CRIRfl ......................... > RCH2C*R’R"(H) RhCl[(P(R1R2R3)3] The validity of this thinking was soon verified by using a rhodium complex of (5)-methylpropyl-phenylphosphine 2 to hydrogenate 2-phenylbutene to 2-phenylbutane in optical yield up to 8%. CH3CHZc=CH2 + (5)-MePrPhP/Rh ------ > cn3cnzc*ncn3 | Ph 2 Ph The next major step was the discovery by Morrison that the ligand need not contain a chiral phosphorous atom. 7 - Indeed, by using neomenthyldiphenylphosphine 5 (NMDPP) and rhodium, they obtained a suprising improvement in optical yield. At about the same time, even more promising results were reported by Kagan and Dang. 8 Reasoning that stereoselectivity should be improved by conformational restriction around the metal, they have achieved great success with 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis (diphenylphosphine)butane 4 (DIOP), which was prepared relatively easily from tartaric acid. The DIOP has been successfully applied in various kinds of catalytic asymmetric syntheses, e.g., hydrogenation of olefins 9'13 and ketones, 14'15 hydrosilylation of ketones 16-19 and imines, 93 hydroformylation, 20'22 Grignard cross-coupling 23'24 and allylic alkylation.25 The neomenthyldiphenyl- phosphine (NMDPP) 26'27 and its diasteromeric isomer 5 (MDPP), 27 introduced by Morrison et al., have been used for the hydrogenation of acrylic acids to give optical yield up to 62%. 26'28 Meanwhile, they also examined a bisphosphine ligand 5 (CAMPHOS), which is derived from camphoric acid.28 u ' PPh2 Pth . 'vphz Pth : ph2 th l A Q Q Dimethylphosphines 1 have been synthesized and used as chiral ligands for a nickel catalyzed cooligomerization of olefins. 29 Optically active amino acids, proline and hydroxyproline, have been employed as chiral sources of phosphine ligands. They are (5)-2-diphenylphosphinomethyl- pyrrolidine 5 3° and (25,45)-4-diphenylphosphino-2-diphenyl- phosphinomethylpyrrolidines 5, 31 respectively, the latter even affording enantiomeric excess of 83-91% in the hydrogenation of<3-acylamino cinnamic acids. 2-2’-bis (diphenylphosphinomethyl)-1,l’-binaphthyl 15 (NAPHOS) 32 whose chirality is due to binaphthyl axial chirality, has been prepared and used as a ligand in several transition metal complexes catalyzed asymmetric reactions. pupa . 2m (filtflzpphz ’3 112?th . R =H. Me R=H, COOBut 2. 5 2 1.9 By this time, the requirements for efficient asymmetric catalysts were becoming clear. The crucial discoveries were: a. Asymmetric catalysis could be accomplished in practical, optical yields by using metal complexes of phosphines chiral at the phosphorous or carbon center. b. Best results were obtained when the catalytic complex was tightly structural. Thus, bidentate ligands, especially if conformationally restricted, were generally most desirable. c. The best substrates were those with one or preferably more highly polar functional groups. Unfunctionalized alkanes gave poor optical yields. Subsequent work has concentrated on the exploitation of this breakthrough. One of the most significant problems in studies on the catalytic asymmetric synthesis was to develop a chiral ligand that will enable the catalyst for a given reaction to be as efficient in stereoselectivity as possible, and considerable efforts have been devoted to searching for new chiral phosphine ligands. Since the catalytic action of coordination complexes is related to the formation and the 33 the most efficient splitting of metal-substrate bonds, asymmetric synthesis should be achieved when complexes containing an "asymmetric" or "chiral" metal atom are used, 34-36 and would minimize the distance between the inducing asymmetric center and the asymmetric moiety being formed. Unfortunately, "chiral metal atoms" are generally not configurationally stable at room temperature, and only in a relatively few cases could complex, containing as the sole chirality center the metal atoms, be isolated as pure enantiomers. 37 In order to improve the configurational stability, tightly bonded ligands (such as the cyclopentadienyl group) must be used. 38 However, this generally lowers the catalytic activity of the complex by a great extent. Despite some interesting attempts, 39'41 conformational analysis of transition metal complexes is still in its infancy and very little is known about the electronic and steric effects on which the stability of diastereomeric organometallic complexes and their conformers are dependent. In 1974, Kumada introduced a new type of phosphine ligands with planar chirality which arises from introduction of phosphino groups into the<3-ferrocenylethyldimethylamino system 42 and their use as chiral ligands in some of the transition metal complex catalyzed asymmetric reactions. Chiral ferrocenylphosphines are readily prepared by way of lithiation of optically resolved(l-ferrocenylethyl-di- methylamine [PA], the lithiation of (B)-FA was previously reported by Ugi and coworkers 42 to proceed with high stereoselectivity to give preferentially (5)-O@{(Bj-2- lithioferrocenyl]ethyldimethylamine. , H.7e - ' I ‘ '- BuLi ‘ ' * .—C\mez ——>- ‘0 CHMeNMez + ‘3 CHMeNMez Li (R)-FA (R)-(R) (961) . (R)-(S) (4%) Reaction of (5)-FA with a slight excess of butyllithium in ether, followed by treatment with chlorodiphenylphosphine to give a new type of phosphine chiral ligands, (5) -OL-[ (B)- 2-dipheny1phosphinoferrocenyl)ethyldimethylamine (PPFA). e LBuLi/Etzo ‘9‘"‘2 b > v ‘ . 2.cwph2 ‘ . R-NME: FrNMEz H He H Me (S)-FA (s)-(R)‘-PPFA Similarly, (B)-Or[(5)-2-dimethylphosphinoferrocenyl]- ethyldimethylamine (MPFA) was obtained in 31% yield with reaction of (B)-FA and chlorodimethylphosphine. ' PMCz 't * ‘CHHemez' 1.8“Li/Et20 ‘CHMCNHEZ D r V ‘- 2.ClPMez. a (R)-FA (R)-(s)-MPFA The stepwise lithiation of (5)-FA with butyllithium in ether and then with butyllithium/ N,N,N',N’-tetramethyl- ethylenediamine (TMEDA) in ether led to the introduction of two diphenylphosphino groups, one onto each of the cyclopentadiene rings to give (5)-Or[(B)-1’,2-bis(diphenyl- phosphino]ethyldimethylamino (BPPFA) in 40% yield. 43 The analogous bis(dimethylphosphino) derivative (BMPFA) was also obtained similarly. 1.80Li/Et20 , ‘ 2.8uLi/TMEDA , ‘ PR2 b ’ >— e’ PR2 \ . \ t ' CHMeNMez (S)-FA R=Ph. (S)-(R)-BPPFA R=Me . (S)-(R)-BMPFA Kumada and coworker also tested some asymmetric hydrogenations 44 by use of several chiral ferrocenyl- phosphine ligands. (5)-(5)-BPPFA exerted an effective chiral influence in the hydrogenation of<1-acetaminoacrylic acid substrate. In the presence of [Rh(1,5-hexadiene)Cl]2 and (5)-(B)-BPPFA in a 1:2.4 ratio, the hydrogenation of OH acetamidoacrylic acid was completed in 20 hours at 50 atm initial hydrogen pressure and room temperature in 86-94%. Also, various kinds of chiral ferrocenylphosphines, which have both planar and central elements of chirality and a functional group on the side chain, have been used as ligands for nickel or palladium complex catalyzed asymmetric cross-coupling reactions. Besides, asymmetric catalytic hydrosilylation of ketones 45'48 and asymmetric hydrogenation of prochiral carbonyl compounds were also examined by using some chiral ferrocenylphosphines as chiral ligands catalyzed with rhodium metal. In their studies, Kumada ascribed the high ability of the chiral ferrocenylphosphines not only to their highly asymmetric structure, but also to the attractive interactions between functional groups on the substrate and on the chiral ligands coordinated to the transition metal catalyst. And it was found that the ferrocene planar chirality played a more important role than the central chirality. Also the dimethylamino group on the cyclopentadienyl ring is the first requisite for the high stereoselectivity. Furthermore, the stereoselectivity was not affected by introduction of substituents onto the diphenylphosphino group of the ligand, but was strongly affected by changing the steric bulkiness of the secondary amino group on the ferrocenylphosphine side chain. 10 One of the advantages of chiral ferrocenylphosphines was ascribed to easy replacement of the dimethylamino group in PPFA by other dialkylamino groups, achieved first by converting the phosphine to the phosphine oxide, then by quaternization of the nitrogen atom, followed by reaction with a secondary amine and finally by reduction with alane. The resulting diethylamino, piperidino, morpholino, and N- methylpiperazino derivatives have been thus prepared in 50- 70% overall yield. a ”‘2 H202 e no)”: 1.2m e D -—-————.- 1 ————————¢- p \ K K ' EHMeNMe, ' EHMeNMe, “W" ' EHMeNRz (8)-(R)-PPFA (om, . 'Ph ’ \ AIH , 2 NR : NEt , N , N 3 1‘:I1 2 2 J > .‘ P e l—\ CHHCNRZ N "Me Also, a hydroxy group could be introduced into the side chain of the chiral ferrocenylphosphines by the following scheme. 5 e Hrk - 'tg-NHe ..‘cI—OA H‘re e 2 Aczo c 1.8uLi ‘4" ‘ , R —->- . R ————o- , R _ ‘ m, ' Pth 2'"2° ‘ m, as" , (R)-(S)-PPFA (R)-(s)-PPFOAc (R)-.(S)-PPFOH RsPth, (R)-(s)-8PPFA (R)-(s)-BPPFOAC (R)-(s)-8PPFOH 11 These chiral phosphines are unique in that they all contain both planar and central elements of chirality and also a functional group such as amino or hydroxyl that can interact attractively with an appropriate functional center of the substrate which interacts with the chiral catalyst. Results should be of interest in the dependence of structural influence on catalytic activity. However, catalytic properties for this kind of structurally different chiral ferrocenylphosphine ligands with transition metals have remained unknown since no such studies has been reported. The investigation of asymmetric catalysis by transition metal complexes has been carried out up to now by using metal complexes containing chiral ligands. In Table 1 the use of the most common optically active ligands is reported. As shown in Table 1, the ligand most used in asymmetric catalysis is DIOP, less frequently used are phosphines 26,42 containing chiral phosphorous atoms. Nitrogen compounds, particularly alkaloids 49 and Schiff bases 50 have been used also with less encouraging results. As for the other types of ligands, phosphites 51 52 containing chiral groups and chiral alkoxy groups also have some significance. There is increasing interest for the latter in particular. 53 Other asymmetric ligands which are seldom used are carboxylic acids, 54 55 55 58 amines, amides, ethers, 57 dioximes and sulfoxides. 59 The highest extent of asymmetric induction has been obtained in hydrogenation when 12 .ccop «dance a o» anonm .whma Co use on» o» a: condemns mucoucg use unease cauducoAUu Dado a muza d and cowouczn as CO cofiaficc< o «gunman Duos one so vocab use coca b .cmbauomoc comb as: scamma canuoesxms some Co on: or» cons: cu agenda cognaabsc co menace are ob ccOQmossoo mousmuk c 0-1 ma MA A m Ha NH om unequscfisdouch: coauccom0adnouchzoo nuances» demons»: coauouou vdocopuco couuccumouczcon co«ae««uo§ou«ao :owumuuuthHom cease sameness co«um~«uoEOuH Awmv cofiasuaambsm couuoahcu>ouchz mcuacsooumnouo couucazaumoschz coguoaxconucuocua: newuosoom aa=OLm axoss< women Chasm moaoadon< managemoza ahsuoontuk cola \ \l uzomodscc use moHo codaocoz scum“ omuuusshm< n.e.eco«uueou uuuhaeueo uduaosshnc sac can: coo: cascade o>uuoc haaeuuuao .d manna 13 DIOP 60 other than diphosphines, 61'62 phosphines containing chiral phosphorous atom 63 54 or ferrocenylphosphine was used. Up to now the choice of ligands has been mainly empirical. Yet, the experimental results so far obtained 'have told us little about structural features of a ligand that will bring the highest stereoselectivity in a given reaction, and all attempts to find relationships between ligand structures and extent of asymmetric induction obtainable in catalytic reactions have failed. 65 Not many different transition metal complexes have been employed in the presence of chiral ligands to achieve asymmetric synthesis (see Table 2). All the elements of the first transition series, with the exception of So, Cr, Mn, have been used, and in Group VIII only Os has not found applications in asymmetric catalysis. The elements of Group IV to VII in the transition metal series seem to be less popular and only molybdenum has been used. Most of the metals have been chosen on the basis of their proven selectivity and higher catalytic activity in the corresponding non-asymmetric reactions. In the few cases investigated, an enhancement of the optical yield in the asymmetric catalytic synthesis has been achevied by decreasing the reaction temperature. 66 Potentially, all types of catalytic reactions in which metal complexes are used as the catalysts can be adapted for asymmetric syntheses. The large number of transition metals still not 14 XX “XXX 3‘ z 0 an O 002 002 DUO 00 U 00.0.0.0 .o.m uo cauuoaxxouau< mumumo mo mamaaou0>m 1 5 accuse audacl whosouda «sass .o.= pocaouum U I U .O.m 1 v uo ceaucauom wuo noduunauoBOMH coauouou ucuauuoamuuc soeumpexomm ceauocuoOAccoupanoo cauuacuuouohnoa caduouauoaaaom cauuooou pdocubucu undamaoonuuouu cadueaxca>ou0>= uo cauuouxaanuoam caguoaxxonuuuouphz cadueaaau0u0u0>m uo cauuocooOupxz um uH 0m 5 am DU «z OU 0h «9 ”can: om>u couuooom uceueuuua cud: cauuecansou cu occauueoa oeuuoss>e< cuuaauueu n308couoao: ed to»: queue: accuses Hetero .m .38. 15 investigated and the large number of conceivable chiral ligands indicates that the field of asymmetric catalysis by transition metal complexes is a very fertile area, both from a theoretical and a practical point of view. Until this point, only chiral phosphines or phosphine- amine combinations have provided satisfactory results. This is a severe limitation, for the synthesis of phosphines is not simple and the derived ligands, once obtained, are often sensitive, especially to oxidation by air. These considerations induced us to investigate some other type of chiral compounds, chiral ferrocenylsulfides, as potential ligands, and their complexes with transition metals as potential catalysts in some asymmetric synthesis reactions. Some ferrocene derivatives with sulfur on side chains have been prepared before, but these were compounds of a nucleophilic or electrophilic substituent. Sulfur was introduced directly to a ferrocenyl ring via electrophilic _sulfonation 67 11. thcou P"2‘30" - M200" )2 ©cu,uu.3. L25 ©c 22s) +©cnzs ©. © ©’ 16 50311 © © czsogn Fe \/ Fe ACZO Sulfonic acid was converted first by PCl3 to the sulfonyl chloride and reduced by LiAlH4 then to the thiol. The thiol was converted to its methyl thioether. The methyl thioether was subjected to electrophilic substitution with bis(dimethylamino)methane. 68 However, these kinds of monosubstituted products were expected to obtain from the activating nature of the methylthio group. @511. @511“ ©sm - Me MCH NMe - - 2 2 2 . HOAC -:5:::>-5Me M22" F. Very few thioether transition metal complexes have been reported as effective catalysts. RhCl3(S(C2H5)2)3 was found to be effective in hydrogenation of maleic acid by James and Mg. 69 Also chiral sulfoxide ligands were active in asymmetric hydrogenation. 7° 17 Recently in this laboratory, 71 lithioferrocene and 1- l'-dilithioferrocene with various disulfides were found to give a series of ferrocenylsulfide derivatives, Fe(C5H4SR)2, where R=Me, i-Pr, i-Bu, i-Pentyl, Ph and PhCHz, by lithiation of ferrocene followed by reaction with appropriate disulfides. They are stable to oxidation but lack of any elements of planar and central chirality on the cyclopentadienyl ring. <§§23> - <§:;§7—Li Fe n-BuLi I Fe - TM E D A TMEDA Li Ssz <§§§;>-sa <§:E§>-sa Me, i-Pr, i'Bu, i-Pentyl :02! u u These ferrocenylsulfide derivatives readily chelate palladium and platinum halides to form ferrocenophane complexes, Fe(C5H4SR)2MX2, (R=Me, i—Pr, i—Bu, Ph, PhCHZ: M=Pd, Pt; x=c1, Br). 18 ,R ‘SR 5 @— (“16lesz ?— \M /x @s 7 ©/ \. lw==Pd.Pi Cl , Br ' Me,£-Pr. i-Bu Ph,CH,Ph 3X 0 II Since the first appearance of ferrocene 74, dimethyl- aminomethylferrocene, 72 l-dimethylaminoethylferrocene, 73 and bromoferrocene, 75 much effort has been expended on the reactions of their lithiation products. 76 Therefore, Brubaker and co-workers continued to introduce the sulfide group onto the cyclopentadiene ring. By lithiation of dimethylaminomethylferrocene in ether solution, followed by reaction with appropriate disulfides, a series of structurally different substituent sulfide ligands, (C5H5)Fe(C5H3-1-CH2NMe2-2-SR), R=Me, Et, n-Pr, i- Pr, n-Bu, g-Bu, i-Bu, g-Bu, i-Pentyl, Ph, Bz, 4-Tolyl, and 4-C1-Ph, which possess planar chirality, were obtained. Similarly, the ferrocenylselenide ligands, (C5H5)Fe(C5H3- CHZNMez-z-SeR) (R=Me, Ph, 4-Cl-Ph), were also prepared. These ferrocenylselenide and ferrocenylsulfide derivatives readily chelate palladium and platinum dichloride to form the desired heterobimetallic complexes, (C5H5)Fe(C5H3-1- CHZNMez-Z-SeR)PdC12 and (C5H5)Fe(C5H3-l-CH2NMe2-2-SR)PdClZ. 19 Through these studies, they found that the palladium ferrocenylsulfide complexes are good selective homogeneous and heterogeneous hydrogenation catalysts for the reduction of dienes to monoenes at room temperature and proposed a possible mechanism. 77 Lack of elemental chirality on ferrocenylsulfide and ferrocenylselenide ligands that have only planar chirality induced them to prepare other chiral ferrocenylthioethers and ferrocenylselenoethers ligands with both central and planar chirality which arise from introducing sulfide groups into the<3~ferrocenylethyldi- methylamine. Later, a series of new chiral ferrocenylthioethers and selenoethers, (5,5)-(C5H5)Fe(C5H3-1-CHMeNMe2-2-SR), R=Me, Et, n-Pr, i—Pr, g-Bu, g-Bu, g-Bu, i—Pentyl, Ph, Bz, 4-Tolyl, 4-Cl-Ph: (5.3)-(c5H5)Fe(8533-1-CHMeNMe2-2-Sen), R=Me, Ph, 4- Cl-Ph were prepared in excellent yield by Brubaker and co- workers by lithiation of optically resolved<2-ferrocenyl- ethyldimethylamine, and treatment with appropriate disulfides and diselenides. Similarly, complexes with palladium and platinum from chiral ferrocenylsulfide and ferrocenylselenide ligands also have been prepared. The chiral palladium ferrocenylsulfide and ferrocenylselenide complexes were found to be effective asymmetric Grignard cross-coupling agents. The palladium ferrocenylsulfide complexes catalyzed the formation of 4- phenyl-l-pentene from 1-phenyl-1-chloroethane and allylmagnesium chloride at 0°C in high yield (> 95%). The 20 resulting configuration in all cases were 5. The enantiomeric excess (e.e) ranged from 16.5 to 26.0 (5) and is much higher than those reported by Kellogg. 78 A mechanism of Grignard cross-coupling reaction for the chiral thioether-palladium was also proposed. Up to this point, the whole framework of a new type of chiral ferrocenylsulfide and selenide ligands has been well developed by Brubaker. As an extension of this work, 79 we report preparations of a series of new chiral ferrocenyl- sulfide and selenide ligands with two sulfide or selenide substituents on each of the cycolpentadienyl rings, and their complexes with palladium and platinum metals as catalysts for some catalytically selective hydrogenation reactions. The object of this research is the development of new chiral ligands and the investigation in the dependence of structurally different ligands on catalytic induction in asymmetric synthesis catalyzed by transition metal complexes. EXPERIMENTAL Air sensitive reagents were manipulated in prepurified argon or nitrogen. Standard schlenk-tube techniques and vacuum lines were employed. Where necessary a nitrogen- filled glovebox was used for transfers. Infrared spectra (IR) were obtained by use of a Perkin- Elmer 457 grating spectrophotometer or a Perkin-Elmer 599 grating spectrophotometer by using neat films for liquid samples and Nujol mulls between CsI or KBr plates or in KBr pellets for solid samples. Mass spectra (MS) were obtained by means of a Finnigan 4021 instrument with INCOS data system. Optical rotations were measured with a Perkin-Elmer 141 polarimeter. Elemental analyses were performed by Galbraith Laboratories, Knoxville, Tennessee. Gas chromatography (CO) was carried out by using a Hewlett- Packard 5880A instrument. All melting points were determined by using a Thomas- Hoover capillary melting point apparatus and were corrected. Proton NMR spectra were obtained in chloroform-d1 solution by use of a Bruker WM-250 spectrometer at 250 MHz. Chemical shifts are reported in ppm downfield from a tetramethyl- silane internal standard. Carbon-13 NMR (broadband proton decoupled and grated decoupled) were obtained by use of a Bruker WM-250 spectrometer at 62.9 MHz. A pulse width (PW) of 13 us and a relaxation delay (RD) of 65 were generally employed. 21 22 All solvents used were A.C.S. reagent grade and were distilled by standard methods before use 80. (5)-N,N- dimethyl-1-ferrocenylethylamine (5-1) was prepared according to Gokel and Ugi’s procedure. 81 Dimethylaminomethyl- ferrocene (12) was made by the standard method 82 or purchased. Bis(benzonitrile) complexes, [(PhCN)2MC12] where M = Pd, Pt, were prepared according to published procedures. 83 The hydrogenation substrate 1,3-cyclooctadiene was obtained from Columbian Carbon Co; 1,3-cyclohexadiene was obtained from Aldrich Chemical Co. These reagents were retreated by standard methods before use. Disulfides, diselenides and N,N,N’,N’-tetramethylene-ethylenediamine (TMEDA) were purchased from Aldrich Chemical Company. A pressure bottle with gauge was used to perform hydrogenations. A. Preparation of Ligands 1-Dime5hylggigomethy1-2-1I-Qis(met511t510)gerroceng (21, A solution of dimethylaminoethylferrocene (12, 2.43 g, 10 mmol) in 100 ml dry ether and 2.7 5 n-BuLi in hexane (5.6 ml, 15 mmol) was mixed at -78°C under argon in a 250 ml round-bottomed flask. After the reaction mixture was stirred for 8 hr at room temperature, the reaction mixture was added to a solution of freshly distilled TMEDA (1.43 ml, 12 mmol) and g-BuLi (2.7 5, 5.6 ml, 15 mmol) in 50 ml dry ether at 23 -78°C and stirred for another 12 hr at room temperature. Then a solution of methyl disulfide (2.83 g, 30 mmol) in 20 ml dry ether was transferred into the reaction flask by syringe at -78°C, and stirred further 24 hr at room temperature. The reaction mixture was hydrolyzed with a cold saturated aqueous sodium hydrogen carbonate (30 ml) and filtered to remove any impurities. The resulting organic layer and ether extracts (50 ml) from the aqueous layer were combined, washed with ice water, dried over anhydrous sodium sulfate, concentrated in vacuum to give a dark oily residue which was chromatographed (60-200 mesh) on a silica gel column by gradient elution (hexane/ether). The product was obtained as a brown oil. Yield: 92%. Anal. for C15H21S2NFe Calcd. C:53.73%, H:6.31%, Found C:54.14%, H:6.23%. MS m/e (relative intensity): 335(M+,100),320(M+-Me,5),286 (M+-SCH3,6),276(M+-Me-NMe2,6),244(M+-NMe2-SCH3,17),23O(M+- NMe2(CH2)-SCH3,10),213(13),164(22),152(3O),121(29),97(18), 91(21),58(Fe,66),56(Fe,47),44(NMe2,32). IR (neat, CsI), 3097(ferrocene C-H stretch),2925-2762(alkyl C-H stretch),1420(ferrocene antisymmetric C-C stretch), 1269,1259(C-N stretch),819(C-H bend perpendicular to the plane of the Cp ring),640(S-C stretch),480(antisymmetric ring-metal stretch) cm'l. 24 1H NMR (5 ppm), 2.18(s,6H,NM_52),2.25(s,3H,SC53),2.26(s,3H, SCfl3),3.24(d,1H,C§2N),3.55(d,1H,C_H_2N),4.09(m,2H,53,H_4,1-I_5), 4.18 (m,4H,C5fi4) ,4.28(m,1H,1-13,_H_4,55) . 13c NMR (5 ppm, in cn3coco3), 19.3(q,SQH3),20.0(q,SQH3), 45.4(q.NMs2).57.4(d.QHNMe2).69.2(d.c3.c4.95).71.0(d..c_'2.g'5) I71'1(dlg’20§’5)I72'3(dlg3lg4lgs)I72'4(dIQ3IQ4IQS)I72'9(dl Q'3,Q'4),73.4(d,§’3,§’4),85.6(S,Q’1),86.4(S,§2),88.2(S,Ql)o -D et am m th 1- - I-bis eth thio rocene 2 R: t The lithioferrocene was made by the same procedure as 21, (R=Me), by using 2.43 g (10 mmol) of dimethylaminoethyl- ferrocene (12), 100 ml dry ether, and 5.6 ml, 2.7 M solution of n-BuLi in hexane at -78°C. Then, the lithioferrocene solution was added a mixture of freshly distilled TMEDA (1.43 ml, 12 mmol) and n-BuLi (5.6 ml, 2.7 M, 15 mmol) in 50 ml dry ether at -78°C. After being stirred 12 hr at room temperature, ethyl disulfide (3.67 g, 30 mmol) was transferred into the reaction flask by syringe at -78°C and stirred for 24 hr. The reaction mixture was hydrolyzed with 30 ml of cold aqueous sodium bicarbonate and filtered off. The resulting organic layer and ether extracts from the aqueous layer were combined, washed with water and dried over NaZSO4. A dark brown residue was obtained after removal of solvent at reduced pressure, and was chromatographed on a silica gel column by gradient elution (hexane/ether) to give a brown oil. Yield: 89%. 25 Anal e for (217112 552N178 Calcd. C:56.19%, H:6.93%, Found C:56.48%, H:6.93%. MS m/e (relative intensity): 363(M+,100),348(M+-CH3,5),334 (M+-C2H5,7),318(M+-3Me,16),302(M+-SC2H5,38),286(23),258(M+- NMez-SC2H5,12),230(l7),165(8),152(19),121(23),97(20),58 (31),56(19),44(12). IR (neat, CsI), 3095(ferrocene C-H stretch),2972-2763(alkyl C-H stretch),1430(ferrocene antisymmetric C-C stretch), 1260,1249(C-N stretch),828(C-H bend perpendicular to the plane of the Cp ring),630(S-C stretch),482(antisymmetric ring-metal stretch) cm'l. 1H NMR (sppm), l.12(t,3H,pC§3),1.19(t,3H,pCfl3),2.16(s,6H, N552),2.53(q,2H,scg2),2.60(m,1H,scgz),2.64(m,1H,scgz),3.2o (d,1H,CflzN),3.55(d,1H,C52N),4.10(m,2H,53,fi4,55),4.16(m,4H, C554),4.29(m,1H,53,H4,55). 13c NMR (5.ppm, in co3cocn3), 15.5(q,pgn3),15.7(q,pgn3), 31.3(t,sgnz),31.9(t,sgnz),4s.8(q,Nngz),58.0(d,gHNMe2),7o.o (d.d.93.§4.95).72.0(d.g'2.g'5).72.4(d.s'2,g'5).73.8(d.§3.g4, 95).75.4(d.Q3.Q4,QS),76.0(d,g'3,5'4),76.3(d,g'3,g'4),32.7 (s.g'1).82.9. 26 -D ami omet - - I-b n- o t o e roce e 23 Banzlil The lithioferrocene was made by the same procedure as 21, (R=Me), by using 2.43 g (10 mmol) of dimethylaminoethyl- ferrocene (12), 100 m1 dry ether, and 5.6 ml, 2.7 5 solution of n-BuLi in hexane at -78°C. Then, the lithioferrocene solution was added a mixture of freshly distilled TMEDA (1.43 ml, 12 mmol) and n-BuLi (5.6 ml, 2.7 M, 15 mmol) in 50 ml dry ether at -78°C. After being stirred 12 hr at room temperature, Q-propyl disulfide (4.51 g, 30 mmol) was transferred into the reaction flask by syringe at -78°C and stirred for 24 hr. The reaction mixture was hydrolyzed with 30 ml of cold aqueous sodium bicarbonate and filtered off. The resulting organic layer and ether extracts from the aqueous layer were combined, washed with water and dried over NaZSO4. A dark brown residue was obtained after removal of solvent at reduced presure, and was chromatographed on a silica gel column by gradient elution (hexane/ether) to give a brown oil. Yield: 82%. Anal. for C19H2982NFe Calcd. C:58.30%, H:7.47%, Found, C:58.48%, H:7.53%. Ms m/e (relative intensity): 391(M+,100),376(M+-CH3,3),346 (M+-3Me,18),316(M+-S(n-Pr),37),272(M+-NMe2-S(n-Pr),12),164 (13),152(17),121(17),97(18),58(40),56(17),44(28). 27 IR (neat, CsI), 3095(ferrocene C-H stretch),2962-2764(alkyl C-H stretch),1448(ferrocene antisymmetric C-C stretch), 1260,1240(C-N stretch),829(C-H bend perpendicular to the plane of the Cp ring),649(S-C stretch),481(antisymmetric ring-metal stretch) cm'l. 1H NMR (5ppm), 0.88(t,3H,rC_I-_I_3),0.95(t,3H,rCfl3),1.46(m, 2H,pCflz),l.56(m,2H,pCfiz),2.17(s,6H,NMgZ),2.50(m,2H,SC52), 2.56(m,lH,SCflz),2.64(m,1H,SCflZ),3.21(d,lH,C52N),3.55(d,1H, CfizN),4.08(m,2H,§3,54,55),4.17(m,4H,C554),4.27(m,lH,53,54, 35)- 138 NMR (5,ppm, in co3cocn3), 13.5(q,r5H3),13.6(q,r5H3), 23.4(t,p5H2),23.5(t,fiQH2),39.l(t,SQH2),39.4(t,SQH2),45.5 (qINMQZ)157-5(drgme2)r69°5(dr.g.3r.c.4195) 171°6(d19.'2:g’5) r71- 9(dlg’zlg'5)[73'3(dlg3lg41§5)174.8(de3IQ4IQS)175.3(dlg’3 I ..C.’4)I75°7(dl§’319’4)182.8(SIQ,1) 182-9(5192) 189-1(SIQ1) ° -D eth l ometh l- -1'-bis i- o 1 th 0 ferrocene 24 R: " e The lithioferrocene was made by the same procedure as 21, (R=Me), by using 2.43 g (10 mmol) of dimethylaminoethyl- ferrocene (12), 100 ml dry ether, and 5.6 ml, 2.7 M solution of n-BuLi in hexane at -78°C. Then, the lithioferrocene solution was added a mixture of freshly distilled TMEDA (1.43 ml, 12 mmol) and g-BuLi (5.6 ml, 2.7 M, 15 mmol) in 50 ml dry ether at -78°C. After being stirred 12 hr at room temperature, i-propyl disulfide (4.51 g, 30 mmol) was 28 transferred into the reaction flask by syringe at -78°C and stirred for 24 hr. The reaction mixture was hydrolyzed with 30 ml of cold aqueous sodium bicarbonate and filtered off. The resulting organic layer and ether extracts from the aqueous layer were combined, washed with water and dried over NaZSO4. A dark brown residue was obtained after removal of solvent at reduced pressure, and was chromatographed on a silica gel column by gradient elution (hexane/ether) to give a brown oil. Yield: 81%. Anal. for C19H2982NFe Calcd. C:58.30%, H:7.47%, Found, C:58.54%, H:7.44%. Ms m/e (relative intensity): 391(M+,100),376(M+-Me,6),346 (M+-3Me,24),316(M+-S(i-Pr),39),304(21),272(M+-NMe2-S(i-Pr), 12),230(10),195(13),164(15),152(23),121(20),97(24),88(12), 58(33),56(19),44(21). IR (neat, CsI), 3097(ferrocene C-H stretch),2960-2765(alkyl C-H stretch),1449(ferrocene antisymmetric C-C stretch), 1260,1241(C-N stretch),835(C—H bend perpendicular to the plane of the Cp ring),652(S-C stretch),485(antisymmetric ring-metal stretch) cm'l. 1H NMR (5.ppm), l.07(d,3H,pCfi3),1.10(d,3H,pC53),l.14(d, 3H,pcn3),1.18(d,3n,pcg3),2.16(s,6H,N552),2.81(h,1H,scg), 3.01(h,1H,SC5),3.17(d,1H,C52N),3.57(d,lH,C52N),4.09(m,2H,53, 84.85).4.19(m.4n.c584),4.32 .72.1(d..g'2. Q’S)I73°2(dlg31941§5)176°1(dIQ3IQ4IQ5) 176-6(dlg'319’4) I 76.8(d,g'3,g'4),79.2(s,5!1),8o.6(s,gz),89.5(s,gl). “-v 2: !' em mom: 2' - -1'-b s n-b t', . o :_r- e-e 25 The lithioferrocene was made by the same procedure as 21, (R=Me), by using 2.43 g (10 mmol) of dimethylaminoethyl- ferrocene (12), 100 ml dry ether, and 5.6 ml, 2.7 5 solution of n-BuLi in hexane at -78°C. Then, the lithioferrocene solution was added a mixture of freshly distilled TMEDA (1.43 ml, 12 mmol) and Q-BuLi (5.6 ml, 2.7 5, 15 mmol) in 50 ml dry ether at -78°C. After being stirred 12 hr at room temperature, g-butyl disulfide (5.35 g, 30 mmol) was transferred into the reaction flask by syringe at -78°C and stirred for 24 hr. The reaction mixture was hydrolyzed with 30 ml of cold aqueous sodium bicarbonate and filtered off. The resulting organic layer and ether extracts from the aqueous layer were combined, washed with water and dried over NaZSO4. A dark brown residue was obtained after removal of solvent at reduced pressure, and was chromatographed on a silica gel column by gradient elution (hexane/ether) to give a brown oil. Yield: 75%. Anal. for C21H33SZNFe Calcd. C:60.13%, H:7.93%, Found, C:59.82%, H:7.71%. 30 Ms m/e (relative intensity): 419(M+,100),404(M+-Me,3),374 (M+-3Me,26),362(M+-C4H9,8),330(M+-S(n-Bu),44),318(M+-NMe2- C4H9,3),286(M+-NMe2-S(C4H9),9),164(15),152(20),121(19),97 (22),58(53),56(17),44(16). IR (neat, CsI), 3095(ferrocene C-H stretch),2996-2768(alkyl C-H stretch),1442(ferrocene antisymmetric C-C stretch), 1275,1261(C-N stretch),830(C-H bend perpendicular to the plane of the Cp ring),635(S-C stretch),480(antisymmetric ring-metal stretch) cm'l. 1H NMR (5 ppm), 0.82(t,3H,5Cfl3),‘0.86(t,3H,6C§3),1.31(m,2H, rCflz),1.43(m,2H,rCflz),l.46(m,2H,pCfiz),l.52(m,2H,pC52),2.17 (s,6H,Nflgz),2.53(m,2H,SCfiz),2.60(m,lH,SCflZ),2.66(m,1H,SC52), 3.20(d,1H,CflzN),3.56(d,lH,CflzN),4.08(m,2H,53,54,55),4.16(m, 4HI C5114) I 4‘29 (ml 1111.113 I34 I35) ' 13c NMR (6 ppm, in cn3cocn3),13.9(q,5gn3),22.0(t,rgH2),22.1 (t,rgaz),32.0(t,pgnz),32.2(t,pgnz),36.6(t,8§H2),36.8 (t,SQH2),45.4(q,NMgz),57.3(d,5HNMe2),69.2(d,53,54,55),71.3 (01,912.95).71.6(d.c'2.g'5).73.1(d.s;3.g,.95).74.5 23 > 35 > 35, 35 > 33 > 33 > 31 > 31 > 33, 31), the largest (0.80 ppm) for the R= benzyl substituent (35) and the smallest (0.0 ppm) for the R= L-butyl (31) and R= 4-Cl-Ph <§;:;>-CH2NM62 Fe é Q~~b 5°” <52: .. é... M-Pd Ra Me, (:1)- Et. (:2)- 100 I.BuL1/Et20 2.8uLf/THEDA @ __’.__ I [PhCleMClz '< ©* 9 n'PrI (El). .1‘Prl (557° Ph, (55)- 82. (25)- 4-Tolyl, 4-Cl-Ph, MhPt Ra Me, (52). Ph, (59)- 82. (51). 4-Tolyl, 4-C1-Ph, (51)- (25)- (£2)- (£2)- ©~ CHzNMCZ Fe ‘4 ‘TMEDA Li R252 <———— CH2NMCZ Ho SR SR R- Me. (2.1) . Rt. (23)- Q’PrI (21)- l-Pr. (2i)- fl'BUtYI, (25). fi‘BUtle (2Q)- I-Butyl. (21)- i-Pentyl, (33). Phenyl, (32). Benzyl, (3Q). 4-Tolyl, (31). 4-Cl-Ph, (33). Fgure 1. Synthetic routes for ferrocenylsulfide compouds, 21:22 101 umm.o uNm.o Emv.H EHM.H umm.o uwm.o BNm.H Emv.d UmH.H GVH.H COH.H GNO.H Em¢.H ENM.H umH.H UNH.H osmm.~ oaom.~ oenm.~ SHo.n £HQ.N poem.~ temm.~ neom.~ poem.~ paom.~ comm.~ mmN.N umN.N mhA.N moH.N th.N me.N Ewd.¢ EmH.v BbH.¢ EmH.¢ Umm.n nEmN.¢ Co~.n mamo.¢ ohm.m Dawn.¢ pna.n mamo.e 0mm.m nfihm.¢ pa~.n memo.e Umm.n QBmN.¢ po~.n maoa.e Cmm.n nfiwm.v ov~.n mamo.e zmno numo .wusumummsmu msznaooo ca .mmuvmmocmm.mmnNummzzmmouannmmov non ammo Boon um .Ema w mzz ad was 0mm .n manna 102 ohm.o Uvm.o 0N0.o Cab.o EHV.H Emn.H uhm.o ubm.o Emo.H Emm.H whH.H usee.a mamn.a moma.a opoa.a oomo.e poem.n ommm.n naHe.~ paem.~ 096m.~ Enm.N Ehm.N m¢O.N mmo.N mmH.N mvo.~ me.N m¢H.N whH.N m¢¢.m on.m om¢.n omh.n 6mm.m omm.m o¢¢.m ohm.n oom.n th.m oom.n oom.n namm.e nahn.e ame.¢ nanm.e msom.¢ smn.e son.enma.e naom.e mann.e 546.8 nam~.e mamo.e sea.v nsma.v msoa.q sea.e naan.e mama.v sma.e .mmouuu .nmouum “mane .zmuo an: .4: .nm .maun .mmum EvH.hlnm.m mm Ewo.hlmm.o Hm Emn.hIVH.h on Ema.hlmo.h am I mm .voswusoo n manna 103 (33) substituents. The compounds with aryl substituents (35 ,31, 33) have smaller differences (35_> 31 > 33) in diastereotopic chemical shifts due to one proton being more closer to the aromatic ring, and are found upfield because of the ring current effect. In the 4-Cl-phenyl (33) and 5- butylthio (31) derivatives, Av/J = 0.0 (appear to overlap). These are the cases in which the outside peaks are small or nonexistent, respectively. The aminomethylene protons of (31), R= 5-butyl and (33), R= 4-Cl-Ph appear as a singlet. The thiomethylene groups (-SCH2-R) in compounds,33, 33, 35, 35 and 35, also diastereotopic, appear the variable chemical shift differences (0.02, 0.08, 0.06, 0.07 and 1.02 ppm for compounds 33, 33, 35, 35 and 35), and are also dependent on the steric crowding at the thiomethylene groups. However, the assignments of the substituted ring protons H3, H4 and H5 in these compounds are difficult since a number of studies 86-89 of monosubstituted ferrocenes have shown that a single substituent may deshield or shield position 2 and 5, or position 3 and 4, in any combinations relative to ferrocene. Figure 2 shows one of the typical 250 MHz 1H NMR of ferrocenylsulfide derivatives, 35, R= g-butyl. The chemical shifts of the substituted ring protons H3, H4 and H5 in 35 are 4.08 (23) and 4.29 (1H) ppm, respectively. In comparison 1 9° and Slocum et al with the results of Dvoryantseva et a 86'88'89'91 the assignment at 4.14 ppm to the protons of the monosubstituted cyclopentadienyl ring (~C5H4) seems 104 .Amusmnq FELL §.mu @._~ §.m~ §.mu _§.r um .WM no ssuuummm mzz ma an: own .~ «Human on em o4. am an jJéééjlqfiqu—Iqqqq«qqqqdiqqqqqmqqqflqfiqququa.14q44_ «amen 105 reasonable, based on 1H NMR integration. Lack of a sharp singlet around 4.00-4.20 ppm is complementary evidence that the ferrocenylsulfides are disubstituted instead of mono- substituted. Rausch and Siegel 87 have assigned the signals in the dimethylaminomethylferrocene (13) at 4.13 and 4.09 ppm to the H2,5 and H3,4, respectively, on the basis of deuterium labelling studies. The 2,5-positions of the monosubstituted ferrocenes except alkyl substituent 86-91 derivatives are sensitive to both deshielding by the inductive effect and shielding by the resonance effect of the electron-donating substituents. In the ferrocenyl tertiary amine thioethers, the deshielding by the inductive effect is stronger than the shielding by the resonance effect of the electron-donating substituents (such as -SR), especially for compounds with R = aryl groups, (35-33). The assignments of substituted ring protons shown in Table 3 are tentative, and deuteration studies must be employed to make unambiguous assignments. Rotation 92 of the pyramidal -NMe2 in these compounds is faster than the NMR time scale at room temperature, thus the two nitrogen methyls appear as a singlet around the 2.04-2.19 ppm region. However, the two methyls appear 1.75 and 2.04 ppm as a singlet in chiral aminoferrocenylphosphino 93 with -dipheny1 and ~dimethyl phosphine groups on each of the -Cp ring. The chemical shifts for different -SR substituents on the cyclopentadienyl ring show in the expected ranges of 0.70-3.50 ppm. Generally, the chemical 106 shifts of alkyl group follow as 55'<‘Y5 < p5 <<15. For example, in compound 35, R= sec-Butyl, pc53 shows at a lower field than pCflz as expected. In addition, the two terminal methyl groups on the -SR substituents, pCH3 in 35 and SCH3 in 35 are also diastereotopic, thus they appear as two well- separated distinct doublets. 13C NMR spectroscopy is a sensitive tool for measuring the electron density distribution on the cyclopentadienyl ring in ferrocene. Substituents on the ring induce screening of the nuclei in two different ways, one due to magnetic anisotropy of the substituents and the second due to the electronic effect of the substituent that possess of both resonance and inductive components. The 13C NMR data of the aminoferrocenylsulfides compounds (31-33) are given in Table 4. Suitably substituted derivatives do possess the diastereotopic carbons, such as compounds, 35, 35, and 35, which contain diastereotopic carbons pcn3, poa3 and 5on3; would absorb at different chemical shifts. One of typical 13C NMR for compound 31, R= 4-tolyl, is shown in Figure 3. Assignments for these compounds are based on comparisons with some similar studies and off-resonance decoupled spectra. Since amine (-CH2NMe2) is a weakly electron-donating group, the inductive effect (deshielding is more sensitive at the 3,4-position) is a little larger than the resonance effect (shielding is more sensitive at the 2,5-position). The two methyls appear around 39.8-40.7 ppm. In contrast, the thio group (-SR) is an electron- 107 I I o.~m N.>m m.¢¢ H.mm H.N> I m.ov. H.Nu m.mo m.mw v.>b «.55 ~.mm I 5N ~.NN «.mm m.mm m.mb II m.m~ o.NN c.~m m.wm «.mv m.hm ~.mb m.~u m.~u m.vu ~.mp «.mm m.Nm m.~m m.mm I mm h.mN «.mm «.mm m.mb II I I m.NN m.mm «.mw H.bm m.m> ~.Nb b.~u ~.mb «.mh «.mm «.mp m.om m.mm I on m.mH m.m~ «.mm >.mp II I m.m~ v.m~ H.mm ¢.mv m.>m m.m> m.~h m.~h m.vh «.mp m.mm m.Nm m.~m “.mm I mm p.0a m.~m m.m> I! I I m.mu m.~m m.mv o.mm o.mh v.Np o.Nh «.mb m.mn o.o> S.Nm m.Nm m.mm I NN c.o~ «.mb I: I I I «.mH ¢.m¢ v.5m m.Nb ~.Hb o.~b v.N> «.mb N.mm m.mm ¢.om «.mm I MN on w> on mo 8.22 z~=w ...m.& .mem mm em & .6. no. am 5 mm mm .ousamhodaou soon am .55 w .m2e\neoooneo 3 Em-£58m;Emu~m§£oIT£m8 .54 3m: 5.: on. .4 «Ba... 1108 .AHm>wuomomou .mconsmu omusuwumnsm um pom .ouoa “a .ozuho no .mpmo .d I I I I «.mv m.mm o.~N I I I e.mv >.wm ¢.Nv I I I >.Hv N.m¢ v.5m I I I I v.mv m.mm m.NN m.NN m.bN N.mm v.NN ¢.6N m.vm N.mm «.mv m.hm m.mh w.m> m.m> m.Nh m.Nb v.Nh m.m> v.m> h.~h «.mb ~.b> m.vv m.~u m.mp m.m> o.~> m.v> m.Nb 0.05 ~.bb ~.v> m.~> m.vb N.Mb m.mm I v.m> o.m> m.mh m.Nm m.~m w.>> N.mb m.Nm b.Nm m.om m.mm ”.mm o.om ".mm mm.mMH e~.~m~ sv.mNH om.mNH no.6md em.mm~ ao.om~ om.bN~ eN.mmH oN.mNH om.mNH em.mNH uO.HVH sv.mNH o¢.hNH em.mN~ m.mm~ “.mNH H.mNH m.mm~ m.m~H n.6NH w.mmH «.mNH H.mNH m.mNH m.o¢~ «.mwa b.mNH an '1' on 111.44. mm .omswucoo e manme .HaaoaIv um .4” mo 89.50QO «22 and .n mung: ELL §.§~ §.§n 8.8m 8.8P §.§m §.n:~ §.Qfl~ 33313333338131??? I* J I J 109 110 donating substituent, and the inductive effect (deshielding is more sensitive at the 4,5-position) is stronger than the resonance effect (shielding is more senisitive at the 1,3- position). Therefore, it is not surprising that all carbons on -SR groups of ferrocenylsulfides appear at a lower chemical field than carbons on the amine group. For example, C1 = 88.2 ppm but C2 = 86.4 ppm in g;, R= Me, (ie. the chemical shield order is C1 > C2). To both carbons (C2 and C1,) that are bonded to both -SR substituents a set of signals, for example, at 86.4 and 85.6 ppm in g;, are assigned to C2 and C1,, and in the mean time these peaks (C1, C2 and C1,) are the weakest peaks in the 13C NMR spectra due to the long spin-lattice relaxation time of substituted carbons. The assignments for aromatic ring carbons (in Table 4) are tentative. Based on some studies 93-94, the chemical shifts in 13C NMR must be C (substituted) > C (meta) > C (ortho) > C (para) for mono- substituted phenyl groups, and C (substituted) > C (para) > C (meta) > C (ortho) for 1,4-disubstituted phenyl groups. For compounds with di- substituted SR or SeR groups on each of the cyclopentadienyl ring, it is difficult to assign C3, C4 and C5. Also C2,, C5, and C3,, C4, which are far away from the C1 amino group (-CH2NMe2) in these compounds are assigned in a set based on the similarity of chemical environment (less affected by C1 and C2) and the number of signals on the 13C NMR spectra. Consequently, the chemical shift for these ferrocenyl- 111 sulfides, g;-;;, follows the order C(aromatic) > C1 > C2, C1,, and C3,, C4, > C2,, C5,. In contrast, the carbon assignments on aminomethylene group, -CH2NMe2, (signals at 56.9-58.0 ppm), nitrogen methyls, —NMe2, (signals at 44.9- 45.8 ppm) and all of carbons on the alkyl substituent (-SR) are clear. The carbons on the -SR groups also followz pg >‘YQ > 59 as in 13C NMR spectra. Most of the IR assignments were made based upon the available literature, 95-98 and are generally consistent with the alkyl, phenyl and ferrocenyl C-H or C-C bend stretches, and the C-N stretch was also observed. The 1 would be indicative of 1,2- adsorption band near 890 cm- disubstitution (as opposed to 1,3-disubstitution), but actually are too weak to be diagnostic. Besides, the C-S and C-Se bonds should have stretches around 600-700 and 507-625 -1 cm , respectively, and ring-metal vibration is in the 1. Lack of two important bands 95 at region of 500-450 cm- 1000 and 1100 cm'1 in the infrared spectra of these ferrocenylsulfides (gi-gg) indicates that the absence of any cyclopentadienyl ring (unsubstituted ring) in these compounds. All IR data for these compounds are shown in the experimental section. For the mass spectra the molecular-ion peaks for all of these ferrocenylsulfides are always observed with high intensities. Other important fragments included are M+-Me, M+-3Me, M+-NMe2, M+-SR, M+-NMe2-SR, -CH2NMe2, Fe, -SR and 112 -NMe2. Beside these major fragments, peaks consistent with the less abundant isotopes 54Fe, 57Fe, and 34S were also detected. 113 3. (1), (g,§)-(CSH3-1-CHM9NHeZ-2-BR)Fo(C5n4-8R), (R=Me, at, Pr, i-Pr, g-Bu, g-Bu, t—Bu, i—Pentyl, Ph, Bz, 4-Toly1, 4-Cl-Ph), (gg-gz). Chiral ferrocenylphosphine ligands which have a planar chiral center due to a 1,2-disubstituted cyclopentadienyl ring are highly effective ligands in transition metal catalyzed asymmetric synthesis. 24'27'32'43'44'64 Though few sulfides have been studied as ligands in metal complexes untill now, a series of previously unknown monosubstituted cyclopentadienyl ring, chiral ferrocenylsulfides, (B,§) or (§,3)-(c5H3-1-CHMeNMe2-2-SR)Fe(c5H5), (R=Me, Et, n-Pr, i-Pr, geBu, g-Bu, t-Bu, i-Pentyl, Ph, Bz, 4-Toly1 and 4-Cl-Ph), and chiral ferrocenylselenides, (§,B)-(C5H3-l-CHMe2NMe2-2- SeR)Fe(C5H5), (R=Me, Ph and 4-Cl-Ph), had been prepared before from this laboratory. 77'79 For the studies of the chiral ferrocenylsulfide compounds, the disubstituted chiral ferrocenylsulfides, (;§- 41), were prepared by using a synthesis procedure similar to that of the disubstituted ferrocenylsulfides, (g;-;g), as was discussed in part (a). Stepwise lithiation of (B)-l- (dimethylamino)ethylferrocene with n-BuLi in ether and then with n-BuLi\TMEDA followed by reaction with different disulfides gave the desired products, (3,§)-(C5H3-l-CHMe- NMeZ-z-SR)Fe(C5H4-SR), (R=Me, Et, Q-Pr, i-Pr, Q-Bu, g-Bu, t- Bu, i-Pentyl, Ph, Bz, 4-Toly1 and 4-Cl-Ph), (gg-gl), in 42— 92% yields (Figure 4). The starting material, (g)-1- (dimethylamino)ethylferrocene, [(3)-1], was prepared 114 v t! 5 Mo .. Me Fe NMQ, BuLi/Etzo 4) Fe U...NMe, Bali/THEM R232 '1‘, ‘3‘0‘39‘1' H $ Cl g'“° \c: [PhCleMClz 8 NM” F0 3’ < F‘ (8.5) Ligands -Pd R= M , 7 . R= Me. (L6)- M 2:, 9.3%. 2t. (.17.). n-Pr. m2)- B'Pr' ”—3)- ;-Pr. (2.9). 1"?“ (12’- Ph, (11). n-Butyl. (L0)- Bz, (12). §'BUtylo (A_)- 4-Tolyl, (1;). i‘g:§{;i (%%gi 4-Cl-Ph, (15). Phenyl, '(AAJ-T . MsPt R- M , . Benzyl. (3.5) - men, 5%). 4-T01y1. (5.5)- Bz, (5Q) 4-C1-Ph, (Al). 4-Tolyl,.(§1). 4-Cl-Ph, (.83) . Figure 4. Synthetic routes for chiral ferrocenylsulfide compounds , 16.-31. 115 according to Gokel and Ugi’s procedure. 81 The lithiation of [(3)-l] was previously reported by Ugi and coworkers to proceed with high stereoselectivity to give preferentially (B)-[(3)-2-lithioferrocenyl]ethyldimethylamine. These chiral compounds, 36-4; and 45, are all brown oils except 44, 46 and 41, which are yellow crystals after recrystallization from acetone/hexane. The quaternary ammonium salts of the general formula [(C5H5)Fe(C5H4-CH2- ' NMeZCHzR)+X', which were prepared in good yields by reaction of the corresponding alkyl halides with (dimethylamino- methy1)ferrocene even at low temperature, were reported by Nesmeyanov et a1. 99'100 In order to avoid possibly obtaining these kinds of amine salts as a yellow powders instead of free amines, it is necessary to deprotonate the reaction mixture, by washing it with aqueous NaHCO3 prior to a final column separation. Furthermore, to increase the yields of the chiral ferrocenyl tertiary amine thioethers, dry diethyl ether rather than halogenated organic solvents such as CHZClz, CHC13 or CCl4 which produce salts, were always used as solvent in the entire synthesis, even though the starting material is very soluble in these halogenated solvents. 1 Table 5 presents H NMR data for chiral ferrocenyl- sulfide compounds (gg-g_). The first (3) configuration refers to the asymmetric carbon atom on the amino group, CHMeNMeZ, whereas the second (S) configuration refers to the planar chirality element of 1,2-disubstituents on the 116 uww.o Unm.o E¢M.H ENM.H umm.o umw.o Enm.H Ehv.d fimH.H GMH.H Umo.H Umo.d Ewm.H 8w¢.H umH.H ”NH.H os>>.~ caeo.~ oamm.~ abd.n £05.N camp.~ 65mm.~ oamm.~ osm>.m osm6.~ ovem.~ mmN.N m¢N.N am~.¢ ”366.4 ama.¢ u aw am~.e useo.¢ sea.¢ n wd amm.¢ mamo.e ama.e u mm naan.e 8366.6 ama.v n ma nam~.¢ Ii mamo.v ama.v s on ammo «Mme am am .musuoummamu Boon um .EQQ w .mza Homo as AmmuvmmocmmAmmnnnmozzmzmouaunzmovuAw.mc you mama fizz I N23 omN .m mafia? H 117 vN.N Umw.o 6¢w.o vdm.o Uom.o Edw.H Bom.~ EN¢.H ENm.N mna.H MEom.H HENV.H u~m.o move.“ umm.o mono.a boom.n nomm.n mm~>.n vamp.~ oam>.~ oamm.~ Ehm.N Efim.N u .nmuuum “mans .mmuo in: .mm .Hm .mHun .zmum 6N¢.H fimv.H an.a flhv.d vhn.H va.H mmm.H mmm.H mmH.N mnm.H moa.~ moo.N com." 6H6." v~o.¢ vam.n 6mm.n vmo.m nanm.e msnm.¢ naem.¢ mam~.e aan.q anamne a on v swannv a mo 6 ago~.¢ 8566.6 been.q mamo.v EH¢.¢ Ehm.¢ NH.¢ BH¢.¢ BmH.¢ BwH.¢ Ema.hlnm.m ENH.thm.w EmN.thH.h EwH.blHo.h .UGfiHUCOU m 0HQMB 118 cyclopentadienyl ring. Basically, the structure of chiral ferrocenylaminosulfide (gg-gl), is similar to that of ferrocenylaminosulfide (gi-gg), except that one proton on the aminomethylene group was replaced by a methyl group. Thus, a doublet around 1.29-1.48 ppm and a quartet around 3.62-4.02 ppm could be easily assigned as a methyl group and a hydrogen atom on the chiral carbon center, respectively. The thiomethylene protons of the (-SCH2-R) in some compounds (g1, g8, 40, 5; and 4;), also diastereotopic, appear in the variable chemical shift and have larger chemical shifts difference than a derivative that does not possess a chiral center (i.e. g;,,;;, 35, g8 and g9). The differences are 0.13, 0.16, 0.07, 0.04 and 0.04 ppm for 11, 18, 49, A; and 4;, respectively. Two nitrogen methyls, also equivalent, appear around 1.93-2.11 ppm depending on the substituents on the cyclopentadienyl ring and also appear at a lower field than those derivatives (c.f. 2.04-2.18 ppm in g;-;;) which do not possess a chiral carbon center because the -CHMeNMe2 group is a stronger electron-donating group than the -CH2NMe2 group, which causes a lower chemical shift for chiral compounds. For example, a difference of 0.07, 0.06, 0.07, 0.10, 0.07, 0.09, 0.08, 0.06, 0.11, 0.04, 0.10 and 0.11 ppm in chemical shifts are observed for compounds (31- g2) and (fig-41) with the same -SR substituents on the cyclopentadienyl ring. Figure 5 shows 1H NMR for chiral ferrocenylsulfide g8, R= g-Pr. The chemical shifts of the substituted ring 119 .Hmlfi_flm .dfl «0 Bfihuommm fizz xH um: omN .m whamwm ELL §.m n.a Q.N @4... Str §.m G-m th §.m §.m fifiqq—‘qq4444141—-__<44q4d L—quqqqqqqdqqqqfiqqq4—«qqq. J? is J 120 protons, H3, H4 and H5 in (§,B)-1-(l-dimethylaminoethyl-z- phenylseleno)ferrocene 77-78 have been assigned as 4.48, 4.34 and 4.28 ppm, respectively. The assignments in chemical shifts of H3, H4 and H5 for these chiral compounds, gg-gl, are not possible due to a broad overlapped signal that must be caused by the electronic effects from the second -SR group on the cyclopentadienyl ring. The protons on the mono- substituted -C5H4 could be assigned to the broad signal around 4.16-4.41 ppm based on the integration of the 1H NMR and comparisons with several known compounds. The 13C NMR spectra are similar to those in g;-;;. The singlet at 9.2-15.8 ppm could be easily assigned to the methyl groups on the chiral carbon center. Compared to the compounds 31-;;, assignments of signals at 39.9-40.7 ppm and 56.0-58.7 ppm to nitrogen methyls (-Nflg2) and the amino- methylene group (-QHNMe2) appear certain and all appear at a lower field (compared with zl-gz). The carbons on the SR substituents (such as<1C, pC,'YC and 5C) and substituted cyclopentadienyl ring (C1-C5) all appear in the range of chemical shifts similar to those in compounds g;-;;. The 13C NMR data for chiral ferrocenylsulfide compounds gg-gz are given in Table 6. Figure 6 shows one typical 13C NMR spectrum of compound 44, R= Ph. The IR and mass spectra of chiral ferrocenylsulfide compounds, (;§-_1), are also similar to those of ferrocenylaminosulfides, (g;-;;). The high frequency bands at 3100-2860 cm'1 are assigned to C-H stretching. The strong 4.44 4.44 4.44 4.44 4.44 4.44 .s - 4.44 4.44 4.44 4.4 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 - 44 4.44 4.44 1- 4.44 4.44 4.44 4.44 4.4 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 . 44 4.44 4.44 4.44 .2 - - 4.44 4.44 4.4 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 . 44 1 M“ 4.44 4.44 4.44 -s. - 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 a 44 4.44 4.44 z; n u 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 . 44 4.44 i, u - a 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 . 44 44. 44> .444 4.6 4.4.444 4422 4:44 44.44 .4444. 4.4 .4 44 :4 .44. 4w 44 44 mm 0.4304093» Boon am .4443 0 .2 \ 300080 :4 AmmuvmmovmhAmmuwlmmzzfléoudnflmov- 3.5 so.“ go: 5442 044 . CO 0.38. 122 I I I I m.cH m.mn m.cm I I I m.m~ N.oe N.N¢ I I I m.~v v.a c.o¢ I I I I ~.N~ N.o¢ m.NN w.N~ 5.5m «.mn v.NN 6.5N m.vm N.mm 5.m m.mn I I c.~m 5.6V m.m~ 5.0V .5~m>4»omdmmu .mconsmo m.mm N.mm 5.wm ¢.wm ¢.55 N.55 m.55 o.¢5 m.M5 m.n5 ¢.M5 ~.~5 o.N5 m.n5 m.m5 m.~5 5.~5 w.mm m.mw Umusuwumnzm um pom mums “a H.m5 o.~5 m.o5 5.55 m.O5 v.O5 «.55 N.o5 c.mw ~.m5 m.c5 5.05 ~.m5 w.mm m.mw v.~5 ~.mm 5.mw I $.55 o.m5 4.9m H.~m ~.Nm ~.m5 n.m5 5.4m v.mm m.55 v.55 .ozuso no .mumd “a v.mm ¢.mm ~.mm c.mm 4m.ch 3N.—m~ am.mmm om.mNH mm.5mu 4m.mm~ sm.cm~ om.mNH mo.ov~ em.mmu oa.mN~ am.5N~ nfl.~¢~ a®.mN~ oo.mN~ 4m.mN~ o.om~ N.mN~ N.@N~ m.mn~ m.m- m.5m~ 5.m- m.w- n.5NH o.m- o.5- 5.mw~ :I O. .II no If! nv .pmswusoo 0 dance 123 45:93 um 74:44 .40 45.4.40QO «.22 Una .4 04:43.4 ELL $-34 e.en 839m 8.4:. 8.8m E.E4~ 8.94:. 8.8W4 124 absorption bands around 1450-1380 cm'1 may be associated with alkyl C-H bend, whereas the broad band absorptions in the 500-450 cm"1 region may be associated with ring-metal vibrations such as asymmetric ring-metal tilt and asymmetric ring-metal stretches. The mass spectrometric data refer to the experimental part. Some important fragments such as M+, M+-Me, M+-SR, n+- NMez-SR, SR (or SeR), Fe, NMez and CHMeNMeZ were obversed. In addition to these fragments, peaks consistent with the less abundant isotopes 54Fe, 57Fe and 34S (or 82Se, 78Se, 77Se and 76Se) were present. 125 (2), (g,§)-(csn3-1-cuxonmz-2-son)ruesnrsan), (3:116, Ph, 4-Cl-Ph), (jg-i9), and (3,§)-(Csn3-1-leoNMQ2-2-SOR)FO (C535), (R=Me, Ph,4-Cl-Ph), (gg-gg). The element, selenium, is in the same group with sulfur, and has similar chemical properties. Sharpless 45 was the first one to make use of the organoselenium reagent, the phenyl selenide anion, in the conversion of epoxides into allylic alcohols. In addition, organoselenium anions are potential nucleophiles that exhibit a strong preference in reaction with soft acids. 47 When organoselenium species contain a good leaving group, they can serve as extremely reactive as soft electrophiles. 140 Thus in general, organoselenium moieties can be introduced into a variety of substrates in either a nucleophilic or an electrophilic sense, and once selenium is incorporated into a substrate, a number of options become available for subsequent functional group manipulations. Finally, most importantly, although most Se(II) species are stable toward p-elimination, their corresponding selenoxides undergo syn-eliminations at or below room temperature. 141 The fi-elimination of selenoxides represent the mildest, general olein-forming reactions known thus far. A series of chiral disubstituted ferrocenylselenide, 48-59, and monosubstituted ferrocenylselenide derivatives, ;1-15, have also been synthesized similarly to those in ferrocenylsulfides, gl-gz and gg-gz, as discussed in section A and B. Since the reactivity of a selenoether group toward 126 introduction onto the cyclopentadienyl ring is generally much less than that of the thioether group, it is necessary to reflux the solution instead of stir it in the synthesis of chiral ferrocenylselenides to achieve yields as high as those achieved in the sulfide derivatives. Table 7 and Table 8 present 1H NMR data for these chiral ferrocenylsulfides, ;;-;§ and 48-52. The resonance effect of a -SeR group is weaker than that of a -SR group due to the -SR group being a better electron-donating substituent and the inductive effect of a -SR group is stronger than that of a -SeR group due to the former's higher electronegativity. The inductive effect (deshielding is more sensitive at 4,5-positions) is larger than the resonance effect (shielding is more sensitive at 1,3- positions) in the case of -SeR and -SR substituted compounds. Therefore some conclusions can be drawn: (i) for -SeR substituted at position 2 of the ring, the inductive effect is much stronger than the resonance effect, whereas a -SR substituted at position 2 of the ring, the inductive effect is stronger than resonance effect, (ii) the inductive and resonance effects of a -SR substituent are stronger than those of a -SeR substituent. Based on the above generalizations, it is expected that the 1H NMR of selenoethers would appear at the higher field of chemical shifts than those of thioethers. As shown in Table 7 and Table 8 the chemical shifts of -NMe2 and -CH2N groups in compound, 42, when R= SePh appear at 2.16 and (3.55, 3.59) .musumummsmu soon um ”muoz 127 344.4 I 444.4 444.4 444.4 344.4 344.4 344.4I44.4 44oI44444 mm 344.4 I 444.4 444.4 444.4 344.4 344.4 344.4I44.4 44oI4444 M4 344.4 I 444.4 444.4 444.4 344.4 344.4 344.4I44.4 4444 44 344.4 I 444.4 444.4 444.4 344.4 344.4 344.4I44.4 :44 44 444.4 344.4 444. 444.4 444.4 444.4 344.4 344.4 I 44444 44 mm~.~ Emn.v 444.4 444.4 444.4 444.4 344.4 344.4 I 4:44 mm mm momma 44:2 nonzo 4n40 4m40 am am .4d3oo .344.» .mzaxn4ooo 34 44mmI4=404444mmI44=zm=xUI4Inz4044I4w.m4 you 332 24 442 444 .4 44444 1128 .343344444 £340,440 4444534944 “4 434 444.4 “a .9340 no .4444 .44 44.444 4.444 44.444 I 34.444 4.444 I 4.44 4.44 4.44 4.44 4.44 4.44 44.4 4.44 I 4.44 04.444 4.444 444I44444 44.444 I 44.444 4.444 4.44 44.444 4.444 I 4.44 4.44 4.44 _ 4.44 4.44 4.44 4.44 4.44 I. 4.44 44.444 4.444 444I4444 .4.444 I .4.444 I 4.44 4.44 44.444 I. I 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 44.444 4.444 4444 4M.HQH I 44.444 4.444 . 4.44 4.44 44.444 4.444 I 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 44.444 4.444 444 44.4 4.44 44.4 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 I 44444 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 I 4444 46 44444 4422 4:44 4.4.44 44.44 mm 4...... 44 .4444. a 44 44 444.444.44.433 300.4 44 .543 w .mZa\4nooo4ao :4 AmmI4=4ovohAmulml4ozzuzz014ln=4ovIAm.mv 34% 4449 mzz 044 .m 44349 129 ppm, compared to the higher field, 2.04 and (3.44, 3.55) ppm values for compound, g5, when Rs SPh. It seems reasonable to assign the chemical shifts in 13C NMR (see Table 9 and Table 10) for compounds, fig-gg, in the following order: C1 > C2 and C1 > C5 > C4 > CSH5 > C3 in -SeR, and C2 > C1 and C1, C2 > C5 > C4 > C5H5 > C3 in -SR. The 13C NMR data for chiral ferrocenylsulfides, ;;-;§ and gg-gg are given in Table 9 and Table 10. The two most important peaks in the infrared spectra of these ferrocenylselenide monosubstituted compounds, ;;-;5, are the bands around 1000 and 1100 cm'l. They obey the 9-10 rule, 95 expressed as follows. Ferrocene derivatives with an unsubstituted Cp ring show absorption near 9 F (1100 cm'l) due to an antisymmetric Cp ring breathing mode and near 10 P (1000 cm’l) due to the C-H bend parallel to the C5H5 ring, but those with both Cp rings substituted, like compounds, Agegg, do not exhibit such absorption peaks. The mass spectra of compounds, ggsgg, gg-QQ, show molecular-ion peaks, expected fragments and smaller peaks consistent with isotopes 328, 76Se, 78Se, 828e, 54Fe and 57Fe. 130 Em¢.¢ Eom.v 35¢.v Em¢.v Emm.hIHN.b EmH.blvm.m EN¢.hlom.h Eom.hlmo.h .Hounmomm Aaounmvm nmmm saw chm.n I th.~ cw¢.n ohm.n u mvo.~ can.n 0mm.n I mma.~ Umm.n oom.n I mmo.~ Gov.n mnH.~ one.n maa.m mmo.~ umo.n m6 mmfiz zmmo .musumuomam soon um .eom w .mze\naooo no .Amm nezmocmmAmmnmuwmzz moufinnmmov you aunt mzz :H mm: omm .m manna 131. .>~m>wuomomms .mcobswo pmuouwumnsm mm pom mums ms .osuuo mo .msmm no .o.vm~ I aN.NMH I m.me m.ms am.Hm~ I I m.mv H.mm «.ms p.me «.me o.ee m.~b I m.om om.m~H m.m- AHoIgmomm .m.mm~ m.mm~ a~.~ma I v.5» m.m> av.m~H ~.m- I ”.me m.mn ¢.>> m.mp ~.e> m.ve m.~s «.mp m.om om.m~H H.mNH AHoIgmvm .m.HvH I as.om~ m.mNH m.mp e.ms om.mN~ m.m- I «.me ~.mn e.me n.mu ~.me m.mp s.~e I m.om am.mN~ I seem .o.~e~ m.oq_ av.m- «.mNH m.pe m.ms m.p> ov.h- u.m- I «.mv m.mm v.ss «.me ~.ee ~.ve m.Hu ~.me c.om am.m- I new o.o~ «.ms H.~s m.mm m.m~ v.me v.em m.~e o.~> e.~e «.me ~.mm «.mm ~.mm I «now .90 $sz mzmm ...m.& ....m.& mm ...u no. .58 A... .3 mm .maSumstEma soon as .aaa.w_.mze\naooomno so AmmIqmmovoeAmmImINmzz~zoI~Inmmov too can: mzz on. .oH manna 132 c. Palladium Complexes of (csna-l-cnzuuez-z-SR)Pe(csn4-8R), R=Me, 8t, g-Pr, i-Pr, Ph, 33, 4-Tolyl, 4-c1-Ph, (gl-gg), and Platinum Complexes of (0533-1-cnznxe2-2-sn)re(csn4- 8R), 2:30, Ph, Bz, 4-Tolyl, 4-Cl-Ph, (ggsgg). Reaction of a benzene solution of the aminoferrocenyl- sulfides (gi-gg, 22:13) with bis(benzonitrile)palladium dichloride or platinum dichloride gave rise to the metal complexes fil-gg. These heterobimetallic complexes are insoluble in benzene. The palladium aminoferrocenylsulfide complexes precipitated immediately upon mixing and the platinum complexes precipitated after the solution had been stirred for 5 days. The palladium complexes are soluble in polar organic solvents such as methylene chloride, chloroform, acetone and acetonitrile, except complex 5;, R=Me, which is only soluble in acetonitrile. The platinum complexes are only slightly soluble in these solvents, but are extremely soluble in acetone. Pure samples could be obtained for palladium complexes as dark brown to red crystals by recrystallization from methylene chloride/hexane and for platnium complexes from acetone as yellow flaky crystals. l-Dimethylaminomethyl-z-1’-bis(methylthio)- ferrocene palladium(II) dichloride, (51), used for X-ray structure studies, was recrystallized slowly from acetonitrile. Table 11 presents the 250 MHz 1H NMR data for the palladium aminoferrocenylsulfide complexes, (gl, 5; and g;- §§). NMR spectroscopy is an extremely valuable technique for 133 .ousuoummamu soou an .:H .mmum “0 .mm .Naum “n .nzo no "muoz cmo.¢ mma.n a~¢.pImm.n II I onm.~ mv¢.~ anv.¢IoH.e aea.uIem.o AHoInmcm mm men.~ coo.¢ moa.n am~.pI-.> II m¢~.~ onm.~ mnv.~ ede.¢IH~.e amo.hIhm.m AmmoInmvm em aoH.v ohv.n mon.n amn.hI~m.h II Iem.n can.~ mam.~ ame.¢Iwm.e am~.bI¢H.n ”mm mm ohm.n mpa.n am¢.nI¢n.> II I ono.~ moe.~ an¢.vIwn.e a-.>IHo.h cam mm usunun oabm n nomm.~ ammo.a omo.¢ mmo.n II awed.” on>.~ mon.~ amm.eImn.¢ I now mm mnn.~ omo.n mac." II mmH.~ can.~ men.~ am¢.va~.e I mmom Hm mm mozzmno «an: ammo.vumo am mm .omsoo .aom w .mzexnaooo no .maocmmxmmImmmoc «mamquImmzzumoIHInmmucs moxmflmaoo you mzz me an: emu .HH manna 134 determining the structure of the species in solution. It does, of course, depend on having nuclei that possess a nuclear spin. This means that not only can the protons present in thioethers and selenoethers ligands be studied but also the selenium (778e, natural abundance 7.5 %, has I=1/2). On the other hand the sulfur isotope 33S with a nuclear spin of 3/2 and a natural abundance of only 0.74 %, is much less useful. Since the sulfur and selenium do not have nuclei that are suitable for nuclear quadrupole resonance studies 101, the only NQR results reported have used other nuclei present in the complex. The aminoferrocenylsulfide ligands undergoe a significant change in the 1H NMR spectra upon complexing with palladium chloride or platinum chloride. There are three possible coordination sites for palladium or platinum metal to coordinate, two sulfur and one nitrogen atom. Therefore the metal atom is expected to coordinate either to two sulfur atoms (structure I) leaving the amine group free, or to one sulfur and one nitrogen atom (structure II) forming a six-member ring rigid structure. Based on the differences in the structures of (I) and (II), we could easily distinguish these two complexes from the 1H NMR spectra. In structure (I), the two nitrogen methyls are expected to appear as a singlet since the amine group is free (uncomplexed). In structure (II), the palladium atom coordinates to both the nitrogen and sulfur atoms, and the free rotation of the pyramidal nitrogen is inhibited by the 135 rigid six-member ring, thus the two nitrogen methyls are expected to appear at different chemical shifts as two distinctive singlets. In addition, the chemical shifts of the two methyl groups in the -NMe2 of the palladium aminoferrocenylsulfide complexes, (il-fig), are more downfield than those in the corresponding free ligands. The splitting of the two nitrogen methyls is large since inversion of the pyramidal nitrogen in the metal complexes is inhibited by the rigid six-member ring structure. The same figure of the two methyls of -NMe2 in the 2-dimethylaminoferrocenylpalladium chloride dimer had been observed before. Also large downfield shifts of the disubstituted cyclopentadienyl protons, H3, H4, and H5 were observed (though they overlapped as a broad signal), probably because of either the magnetic anisotropy or the inductive effect of the metal chloride. Figure 7 shows a typical 1H NMR spectrum of the free ligand, 31, and its palladium complex, :1. As is illustrated in Figure 7 the two singlets at 2.43 and 3.16 ppm, which were compared with complex §§, are assigned to two nitrogen methyls instead of a singlet around 2.08 ppm in free ligand 31. The aminomethylene protons are assigned as two distinct doublets at 2.83 and 4.00 ppm, respectively. In contrast to a singlet at 2.26 ppm for the two methyls on the phenyl in the free ligand, they are split into two different singlets in the complex at 2.24 and 2.34 ppm, probably because one 136 (ll) (21) L JUL. 'IIITTIT 1111IWTTII1I1IITTTWIWTflITTTTHHIIWII11111177111111T]11117 (3.6 77.fl 53.2 55.fl fi.fl 23.0 2.63 Figure 7. 1H NMR spectrum of 3; and its palladium complex, :1, Rs Phenyl. 137 -SR group bonds to metal palladium but the second -SR remains free. The protons on both cyclopentadienyl rings appear as a broad signal around 4.21-4.41 ppm. Unfortunately, 13C NMR data for these complexes, gl-gg, could not be obtained. The use of infrared and Raman spectroscopy as techniques for determining structures is not as straightforward as X-ray diffraction for two reasons: (i) for complex polyatomic molecules of relatively low symmetry, more than one fundamental mode often contributes to a given band in the spectrum, (ii) in order to investigate the bonding between metals and ligands, it is generally necessary to carry out a detailed force field analysis, and this requires data from many isotopically substituted species. The metal-sulfur and metal-selenium bands are often weak and occur in the region of the spectrum similar to that of the metal-halogen bands of the halogen in the same period of the periodic table. Thus metal-sulfur vibrations occur around 300-340 cm"1 and metal-selenium vibrations around 200-240 cm'l. The most important exceptions to the above generalizations are the thioether-bridged platinum(II) complexes, (R28)2Pt2X4, where the metal-S stretching vibrations around 380-420 cm-1 reflect the much stronger metal-S bond when the thioethers are bridging rather than terminal 102 -- a result confirmed by X—ray diffraction. 103 Another often used source of data concerning the nature of metal-ligand bonding is the influence of a ligand in the 138 trans position (often M-Cl) on the metal-ligand bonds, 104'105 preclude any precise analysis although complications of the trans influence results. However it can be stated that thioether or selenoether ligands generally show greater trans influence than nitrogen donors and smaller trans influence than teriary phosphines or arsines. 105 The individual metal-Cl and metal-N stretching modes of the complexes, §;-§§, are given in the experimental part. The metal-N occurs at the higher frequency, around 460-475 cm'l. As is illustrated in the IR spectra, replacing an -SR group by -SeR gives a larger drop in VPt-E stretching vibrations for Pt(II) than Pd(II). Thus, whereas the relative D-bonding contribution in palladium(II) thioether or selenoether bonds increases in the order of Pd-S < Pd-Se, the order for platinum(II) appears to be anomalous, Pt-Se < Pt-S. The anomalously small 0 component in the Pt-Se bond is ascribed to a poor match between the relevant orbitals. The mass spectra have fragments consistent with those of the free ligands, except the absence of the parent peaks due to the weaker metal coordination bonds. 139 D. Palladium Complexes of (g,§)-(Csn3-1-CnMeNMeZ-2-8R)re (C534-8R), (R=Me, at, n-Pr, i-Pr, Ph, Bz, 4-Tolyl, 4-c1- Pa), (gz-zg), (3,§)-(csna-i—cnxenuez-z-senIPe(csa,-senI, (R=Me, Ph, 4-C1-Ph), (lg-11) and Platinum Complexes, ( R=Me, Ph, Bz, 4-Tolyl, 4-01-Ph), (lg-gg). Reaction of chiral (R,§)-(C5H3-1-CHMeNMe2-2-SR)Fe(C5H4- SR), 36-11, or (R,§)-(C5H3-1-CHMeNMe2-2-SeR)Fe(CSH4-SeR), (Ag-59), in benzene with palladium(benzonitrile) dichloride or platinum(benzonitrile) dichloride gave the expected metal complexes, 61-11 and lg-gg. These heterobimetallic complexes are insoluble in benzene. Palladium complexes, 61-11, precipitated immediately after stirring the solution overnight, whereas platinum complexes, 1_-_;, were obtained after stirring the solution for 7 days. The palladium complexes, dark red to burgundy, are highly soluble in organic solvents such as CHZClz, acetone, CH3CN and CHC13, whereas platinum complexes which precipitated as yellow flaky crystals are only soluble in acetone. Pure samples were obtained after recrystallization from methylene chloride/ heptane for palladium complexes or from acetone for platinum complexes. The bimetallic complexes are sufficiently soluble in CDCl3 to obtain 1H NMR spectra. The 1H NMR data for the chiral palladium ferrocenyl- sulfides complexes, _1- 4 and 15-11 are given in Table 12. The strong deshielding at the<1~protons of the metal 140 .musumumafimu Eoou um “muoz mmn.N mVN.N EmH.v me.m fivm.a flmv.H flvm.H aoe.pInn.> voa.¢ sH¢.¢Ion.¢ ama.hIHm.o am~.nI¢~.> ooa.¢ ann.¢I-.e sac.sInm.o awn.blmN.h U0N.¢ Bw¢.vaN.¢ EvN.hImH.h Enm.hlcw.h UHH.¢ 50¢.clmN.¢ Evm.hlam.m vma.v smv.eIom.¢ I AHoInmcw AmmoIzmvm Nmm 2mm .aom w .mzexnaooo as .maoomfixmmIemmovmm AmmI~I~ozzmzmoIaInmmocHIAw.mc moxmaoeoo you mzz mu um: om~ .«H manna 141 complexes is due to the magnetic anisotropy and the inductive effect of the metal halide and is also due to a little tilting of the cyclopentadienyl rings where the (x-protons are farther from the shielding iron atom. 106 The chemical shift differences of the two methyl groups in the -NMe2 of the chiral (B,§)-(C5H3-1-CHMeNMe2-2-SR)Fe(C5H4-SR)- PdClz complexes, 61-11, are larger than those of the (C5H3- l-CHZNMeZ-Z-SR)Fe(C5H4-SR)PdC12 complexes, 53:58, because a chiral center of the -CHMeNMe2 group induces a different geometrical arrangement of the rigid six-member ring structure. The differences are 0.91, 0.95, 0.96, 0.95 and 0.96 ppm in chiral complexes, 61, 11-15, compared with 0.75, 0.71, 0.71, 0.73 and 0.72 ppm in complexes, 51, §§-§§. The doublet at 1.45-1.52 ppm is assigned to the methyl group on the chiral center, -CHMeNMe2, whereas the quartet at 4.10- 4.15 ppm is assigned to the proton on the same chiral center depending on the substituents on the cyclopentadienyl ring, and they all have a downfield shift of 0.14, 0.07, 0.09, 0.06 and 0.12 ppm for the chiral methyl groups and of 0.14, 0.20, 0.18, 0.19 and 0.20 ppm for the protons on the same center in complexes, g_ and 11-15. Also, the protons on both cyclopentadienyl rings have a larger downfield shift than those in the free ligand, though they appear as a broad overlaping signal in the complexes instead of three well- separated broad peaks. Figure 8 shows one of the typical 1H NMR spectrum of the chiral ferrocenylsulfide ligands, 56, and its palladium 142 (4.6.) (13.) L Lot WTTTTI1ITITYITIIIITITTII1IWTIII1ITIITIT1IIII1ITI1II1ITIIITIYTI "7.8 S.Ei 55.6 ‘9.fl :3.@ 22.8 Figure 8. 1H NMR spectrum of 15 and its palladium complex, 143 complex, 11. Unfortunately 13C NMR for these metal complexes could not be otained. Earlier studies 79 from this laboratory showed that the 1H NMR spectra of the chiral (3,5)-1-(1-dimethylaminoethyl)-2-(arylthio)ferrocene palladium dichloride were very temperature dependent. Results showed that these difference are due to the variable rates of pyramidal sulfur inversion -- breaking the Pd-S bond and reforming it with the other configuration at the sulfur atom. Inversion at a coordinated thioether site was first demonstrated in PtClZ(2,5-dithia-hexane), for which the two sets of triplets of the methyl protons coalesce to a single triplet above 95°C. 107 Much of the work in this field 107-117 determines coalescene temperatures of the palladium and platinum complexes, indicative that the inversion is not a dissociative-associative mechanism. A simplistic view of the mechanism generally proposed 111 is the displacement at the central metal ion of the lone pair of the thioether or selenoether used in the M-S or M-Se bonds by the lone pair, which is not involved in the bonding via a planar intermediate in which the sulfur or selenium atom remains pyramidal. Ease of exchange between free and coordinated ligands is in the order TeEt2 >> SeEt2 > SEtZ, as are the relative energy barriers. 113-115 This suggests to us that the Pd-S bond is the weakest bonds at the square planar palladium atom in the complex, and more importantly it is useful as an explanation of the reaction mechanism in selective hydrogenation of 1,3-cyclooctadiene with these 144 complexes as catalysts. S-dealkylation was first reported in 1883 113 for the S-demethylation of dimethyl thioether by PtClz. However, the subject was neglected until the 60s when it was found 119-12° that 8-(methylthio)-quinoline complexed as a neutral ligand toward palladium(II) and platinum(II). However, S-dealkylation was not observed in this work as it was with similar complexes, as a matter of fact attempted to S-dealkylation in these metal complexes led to decomposition. All of the analyses of the metal complexes, 51-81, support their structures and are not like various reported dimers, 121 or with only Pd-N chelation. The IR and mass spectra for these metal chiral ferrocenyl sulfide complexes, 61-15, 18-82, are generally similar to those of metal complexes, 51-61, discussed in section (C). 145 B. x-ray structure studies of 1-dimethy1aminomethy1-2-1'- bis(methy1thio)ferrocene Palladium Dichloride (61). For the palladium or platinum complexes of thioether and selenoether, the observed metal-S or metal-Se bond lengths are shorter than expected on the basis of the sums of the covalent radii, an observation that has often led to the suggestion that these M-S bonds, together with the Pd-Se bond where the same is also found, involve some 9 back- donation from metal to sulfur or selenium. . In all the complexes the bond angles about sulfur and selenium are approximately tetrahedral, consistent with the presence of one lone pair of electrons in an orbital that can be roughly described as sp3. Distortions from the ideal tetrahedral angle would be expected and are indeed found where the metal and sulfur and selenium atoms form part of a ring. Most M-S-C angles lie below rather than above the tetrahedral angle, an observation that can be attributed, probably either to the large steric effect of a lone pair or to less complete involvement of the s orbital in hybridization. 104 The crystal structures of 1-1’-bis(iso-butylthio)- ferrocene palladium dichloride (26) and (R,S)-1-(1-dimethyl- amino)-2-(methylthio)ferrocene palladium dichloride (66) have been determined in this laboratory. 77 The palladium atom coordinates to both sulfur atoms in complex 66, and to both nitrogen and sulfur atoms in complex 26. In both complexes the environment of the palladium atom is described 146 as square planar with two cis chlorines and two sulfur atoms, in 26, and one nitrogen and one sulfur atom, in 26, respectively. Some other similar palladium ferrocenylphosphine complexes, [PdC12(PPFA)] (21) 122 and [PdC12(BPPFA)] (22), 123 were reported by Kumada and coworkers. Crystal structure analysis of chiral phosphine transition metal complexes has proved to be a useful tool in the elucidation of the mechanism of stereocontrol in catalytic asymmetric reactions, especially in the rhodium- catalyzed hydrogenation of enamide precursors of amino acids. 124 Kumada also proposed that the high efficiency of the PdC12(DPPF) catalyst could be ascribed to its large P- Pd-P angle and small Cl-Pd-Cl angle. 125 In order to understand the structural and the catalytic properties of the disubstituted metal ferrocenylsulfide complexes, the X-ray crystal structure of complex, 61, was also examined in detail. 147 F. Selective Hydrogenation of Conjuated Dienes to Monoenes with Metal Complexes in Organic Solvents at Room Temperature. The hydrogenation of olefins has been studied extensively, perhaps more than any other reactions catalyzed by soluble metal complexes. 124b'124d'126 This intensive study seems anomalous because soluble catalysts are seldom used for olefin hydrogenation in industry or in organic synthesis. Heterogeneous catalysts are ususally more active and more convenient for practical applications such as the hydrogenation of cyclododecatriene to cyclododecane or of dicyanobutene to adiponitrile. The sole commercial use of a soluble catalyst for olefin hydrogenation is the reduction of an unsaturated amino acid to a precursor of the drug L- dopa. Even though this operation is conducted on a small scale, it is interesting because it involves asymmetric induction through use of an optically active catalyst. This selectivity is the major advantage of a soluble catalyst. The best studied soluble catalyst for olefin hydrogenation is Wilkinson’s catalyst RhCl(PPh3)3. Generally, the most active catalysts are to be found in the salts and complexes of Rh, Ru and Pd. The catalytic activity of the transition-metal salts and complexes is the result of a delicate balance of valence states and strengths of chemical bonds. 127 Too strong a bond between the hydrogen donor and the transition metal results in stable compounds showing no catalytic activity. Similarly, there is 148 no catalytic activity if reaction between the hydrogen donor and the transition element cannot occur. The activity of the catalyst depends on the existence of free coordination sites on the central metal or on the possibility of producing a vacant site by loss of a ligand. Therefore, the coordination number of the metal complex should be less than the maximum possible, or for saturated complexes, the ligand-metal bond strength should be such that dissociation is possible or that ligand displacement by a solvent, hydrogen donor, or substrate hydrogen acceptor can occur. In 1967, PtC12(SPh2)2 was found to be selective for the hydrogenation of dienes to monoenes in the presence of SnClz 128. Treatment of PdClz or NadeCl4 with tertiary amines resulted in an active selective catalyst. 129 The same was true of PdClZ when treated with 2,2’-bipyridine and NaBH4. 13° The thioether-rhodium complex, RhCl3(SEt)3, was used in the hydrogenation of the maleic acid. 69'131'132 149 (a) Selective Hydrogenation of Conjuated 1,3 Cyclooctadiene to Cyclooctene with Complexes (61-22, 66-62, 61-62, 11- 11)- The palladium aminoferrocenylsulfide complexes have been used as catalysts for reduction of 1,3-cyclooctadiene to cyclooctene in various solvents at room temperature. Hydrogenation of 1,3-cyclooctadiene occurred fast in acteone at 103 psi initial hydrogen pressure as shown in Table 14. This is a homogeneous system without any H20 or reducing agents, and reaction proceeded at a normal rate (turnover rate from 79.0 to 722.4 mol/mol pd.h). The conversions and selectivities in all cases were fairly high, up to 100% and 96.8%., respectively. The original red solution became yellow clear with some black precipate, probably palladium metal, as time passed, but the solution remained homogeneous. The principal products at the end of reaction was cyclooctene with some cyclooctane. The percentages of products were determined by gas chromatography. The ratio of (cyclooctadiene + cyclooctene) to cyclooctane were separated by more than 0.7 min. in the CC. spectrum, and the ratio of 1,3-cyclooctadiene to cyclooctene was determined by 250 MHz 1H NMR as shown in Figure 9. The chemical shifts of the central and outer olefinic protons of the diene appear around 5.8 and 5.6 ppm, respectively, while that of the monoene is near 5.6 ppm. Therefore, the ratio of monoene to diene is calculated by following equation. 150 Table 14. Hydrogenation of 1,3-Cyclgoctadienea with 66- 62 -- Effect of Catalysts . Catalyst Solventc Turnover Conver. Products(%) Select. /PdCl2 Rate (%) Monoene Alkane (%) SPh acetone 363.4 100 93.8 7.22 93.8 882 acetone 79.3 100 92.8 7.20 92.0 S(Ph-CH3) acetone 390.3 100 88.6 11.4 88.6 S(Ph-Cl) acetone 722.4 100 96.8 3.19 96.8 a: 7.45x10"3 mole of substrate. b: ca alyst = [(C5H3-1- CHZNMez-Z-SR)Fe(C5H4-SR)]PdC12, 2x10' mole, at room temperature, 103 p51 initial pressure. c: 9 ml of solvent. 151 43333333303 2:. .AoGESaeoauoepufi we. oco—voguefiuaué; co 9.3.2... «5 .Eefiueu_ueuuoopu>.uIm.~ co 5.2 a. 3: SN so :33.— u—etos .m 2:3... m6 o.» Hm 9m Sea a a 4 _ O 152 Monoene Area(5.6)-Area(5.8) Diene Area(5.8) In Table 14. it is apparent that the turnovers rate are dependent on the catalytic activity of the different complexes. The more the steric crowding and electron- withdrawing of the substituents on the cyclopentadienyl, the more favorable the selective hydrogenation. The hydrogenation reaction failed when palladium selenide or platinum sulfide were used as catalysts, suggestive that the breakeage of the metal-sulfide bond (or metal-selenide) may be a key step for the catalytic hydrogenation since the Pd- Se or Pt-S bond is stronger than the Pd-S bond in these catalysts. Table 15 shows the solvent effect of the hydrogenation reaction using complex, 62, as catalyst. The conversion and selectivity reduced when H20 was added to the acetone or when reaction was carried out in a stronger coordinating solvent such as THF. However, the catalyst still remained active in a weaker solvent such as CHZClz, an observation which had not been observed before in this laboratory with the similar ferrocenylsulfide palladium catalysts. The same hydrogenation reaction was examined by using chiral ligand complexes, 7- 9 and 11-16 with acetone as solvent. Conversions in all cases were 100%. The turnover rates, percentages of monoene and selectivities are strongly dependent on the different substituent groups on the 153 Table 15. Hydrogenation of 1, 3-Cyclooctadienga with Catalyst 62 -- Effect of Solvents Catalyst Solvent Turnover Conver. Products(%) Select. /PdC12c Rate (%) Monoene Alkane (%) S(Ph-Cl) acetone 722.4 100 96.8 3.19 96.8 " acetone/ 141.8 82.0 76.5 5.50 93.2 H20 u THF 383.8 62.6 60.4 2.13 96.6 n CHZClz 178.7 80.0 79.5 0.47 99.4 a: 7.45x10'3 mole of substrate. b: 9 ml of solvent. c: catalyst = [(C5H3-1-CH2NMe2-2-SR)Fe(CH -SR)]PdC12 , R=4-Cl- Ph, 2x10'5mole, at room temperature, 103 psi initial pressure. 154 cyclopentadienyl ring; i.e. different catalysts. The percentage of monoene and selectivity were both 100% for complex, 62, R = Et. There does not seem to be any relationship between catalytic activity and the different complexes used as catalysts based upon the data in Table 16. Failure of the hydrogenation reactions using chiral palladium selenide or platinum sulfide complexes was observed again as mentioned before. Meanwhile, the solvent effect, using complex 12 as catalyst, was also studied in detail as shown in Table 17. In a stronger solvent, such as pyridine, catalytic activity for the conversion was reduced dramatically, down to 7.23%: however, selectivity remained 100%. Our results indicate that the significance of the solvent lies mainly in its tendency to coordinate. Strongly coordinating solvents inhibit the catalytic activity, whereas weakly coordinating ones do not. Results obtained from the hydrogenation in different solvents suggest the following increasing order of catalyst- solvent interaction: CHZClZ < (CH3)2C0 < THF < pyridine. This roughly parallels the order of increasing coordinating efficiency of the solvents. Monoene yields ranged from 92.2% in methylene chloride to 7.23% in pyridine for chiral palladium complex catalysts. Metal-solvent interactions may range from weak dipole-dipole interaction or solvent cage formation to chemical bonding or coordination, as in pyridine. This could be confirmed by 250 MHz 1H NMR spectra: 155 Table 16. Hydrogenation of 1,3-Cyclooctadienea with Catalysts 61-62, 11-15 and 12 -- Effect of Catalystsb. 62.25;;"’23;EQEEEEEQSSQETSEEI’XII—33322;Iii-"25.2.2;. /PdC12 Rate (%) Monoene Alkane (%) SCH3 acetone 45.7 100 95.5 4.48 95.5 SCZH5 acetone 9.7 100 100 0.0 100 S(n-Pr) acetone 18.3 100 92.3 7.70 92.3 SPh acetone 114.5 100 86.4 13.6 86.4 882 acetone 62.4 100 89.7 10.3 89.7 S(Ph-CH3) acetone 291.9 100 84.6 15.4 84.6 S(Ph-Cl) acetone 645.1 100 91.6 8.43 91.6 SPh/Ptd acetone - - No H2 Uptake - SePh/Pd acetone - - No H2 Uptake - a: 7.45x10"3 mole of substrate. b: catalyst = [(2,2)-(C5H3- l-CHMeNMez-Z-SR)Fe(C5H4-SR)]PdC12, 2x10' mole, at room temperature, 103 psi initial pressure. c: 9 ml of solvent. d: platinum complex. Table 17. Catalyst /Pdc12c S(Ph-Cl) 156 Hydrogenation of 1b3-Cyclooctadienea with 16 -- Effect of Solvents . Solvent Turnover Conver. Products(%) Select. Rate (%) Honoene Alkane (%) acetone 645.1 100 91.6 8.43 91.6 acetone/ 254.0 81.2 75.3 5.90 92.3 H20 THF 371.6 95.0 84.6 10.4 89.1 pyridine 82.1 7.23 7.23 0.0 100 CHZCl2 165.6 93.8 92.2 1.55 98.3 a: 7.45x10'3 mole of substrate. b: 9 ml of solvent. c: catalyst =[(2,6)-(C5H3-l-CHMeNMe2-2-SR)Fe(C5H4-SR)]PdC12, 2x10 mole, at room temperature, 103 psi initial pressure. 157 the chemical shifts of the complex-coordinated pyridine have a larger downfield shift than free pyridine. Not suprisingly, both conversion and selectivity were a function of the additives employed. With AgNO3 added in acetone, the turnover rate and conversion decreased but selectivity increased somewhat (up to 100%). In anhydrous acetone solvent, the Ag+ slowly scavenges the Cl' from the hydrogenation cycle and inhibits the enhanced hydrogenation of the cyclooctene to cyclooctane. However, with added AgNO3 and H20 in acetone the Ag+ ion precipitates immediately all of the Cl' from the palladium complexes into the aqueous phase, which causes reduction of the catalytic activity of the complexes. In some cases the hydrogenation completely failed, depending on the order adding of AgN03 and H20 into the system (see Table 18). Futhermore, the effect of a formation of a hydroxo bond at the palladium atom due to the hydrolysis reaction can not be excluded 133. The quaternary ammonium salts may precipitate and act as the catalyst, or a Pd2+ hydroxide species dissociated from the thioether may precipitate. The insertion of olefins and acetylene into Pd-H and Pt-H bonds have been studied extensively. 134-135 It has generally been accepted that the formation of the metal- hydrido bond and its reaction with unsaturated compounds are one of the key steps in the overall reactions 136. Thorn and Hoffmann have carried out a detailed theoretical analysis of the reaction of ethylene with trans-(H3P)2Pt(H)Cl. 137 They 158 Table 18. Hydrogenation of 1, ,g- -Cyclooctadienea with 74 -- Effect of Additives Catalyst Solvent/ Turnover Conver. Products(%) Select. /PdC12c Additive Rate (%) Monoene Alkane (%) S(Ph-Cl) acetone 645.1 100 91.6 8.43 91.6 " acetoae+ 134.1 22:5 22.5 0.0 100 AgNO3 " aceto e+ 74.2 14.53 14.5 0.0 100 AgNO3 Hzoe a: 7. 45x10“3 mole of substrate. b: 9 ml of solvent. c: catalyst [(3, 2)- (C5 H -1-CHMeNMe2- -SR)Fe(C5 H -SR)]PdC12, 2x10 me e, at room empsrature, 103 psi iniéial pressure. d: 4x10 mmol. e: 2x10 mole. 159 found that the ground state of the five-coordinate complex 2 could not be transformed readily into configuration 2 (with coplanar ethylene and hydride ligands) as required for insertion. H H L \ I...” .1333... L \ I. _. H 1’ L I L/I C1 C1 A 2 In contrast, they found that the perpendicular ethylene in a four-coordinate complex 2 could easily rotate to give the coplanar complex 2 and insertion (the normal preference for a perpendicular orientation is apparently the result of steric and not electronic factors). 138-139 L L / 0.3eV 1.th -|| ---------- > L-+Pt -/ / / H H 9 2 They therefore proposed that the insertion of olefins into the Pt-H bonds of planar complexes proceeded via a four-coordinate (with the olefin replacing a ligand and achieving a coordination site cis to the hydride) rather than a five-coordinate entity (with no ligand loss prior to 160 coordination and insertion of the olefin). Thorn and Hoffmann also suggested that their results should extend to acetylenes and to Pd-C and Pt-C sigma bonds, and thus that olefin and acetylene insertions into Pd-C and Pt-C bonds should also prefer four-coordinate mechanisms over five- coordinate ones. Figure 10 presents a possible mechanistic scheme for the homogeneous selective hydrogenation of 1,3-cycloocta- diene. The hydrogenation proceeded either from 122 via four-coordinate intermediates, 126, 126, 121, and 1_2, then back to 122 having a cycle, or from 122 via five-coordinate intermediates, 112, 121 and 122 then back to 122. Although an analysis of 195Pt NMR chemical shifts in a range of complexes according to Ramsey’s equation has led to the suggestion that the covalency of platinum(II)-ligand bonds increases in the order NMe3 << Cl’ < C2H4 < Mezso, SMe2 < PMe3 < SeMe2 < AsMe3 < SbMe3 < TeMe2 < I'. Breakage of Pd-S, but not Pd-N or Pd-Cl bonds was supported by many experimental results: (1) X-ray studies show the length of the Pd-S bond is longer than that of Pd-N or Pd-Cl bonds, suggestive that the Pd-S bond might be the weakest, (2) all palladium selenide or platinum sulfide complexes used as catalysts in acetone could be recovered completely after failure of the hydrogenation reaction and would explain that breakage of the Pd-S bond should be the first step in the mechanism since Pd-Se or Pt-S is stronger than Pd-S and (3) the variable temperature 1H NMR spectra of complexes showed 161 .HmSwoouumm IoanuahxamfipI.H.~ «Ion .mumfiomsumucfl cowumcacuooo Insow m masons» mcmflpmuoooHUMUIm.H mo cofiumswmouumn m>auomamw msowsmmoso: ego mo msmficmnoms manflmmom .urI Had a 1|); A‘Inl .lo/ .01/ v1 \7 P.\ .e\ {~22 1 I I \ on; .014 a _U I/ _. mm _o\ _ x. 2N3... 0L ouuu «d... /P.\ o u-.. I .II\\\\. ... O. O "l\ 9 .OH musmfim 162 that even at room temperature the pyramidal sulfur inversion in two different conformational structures could occur by breaking the Pd-S bond and reforming it with the other configuration at sulfur. The insertion of olefin into the Pd-H bond of planar complex 121 proceeds via a four-coordinate intermediate, and then takes up a HCl molecule to form a five-coordinate trigonal bipyramid (TBP), 122, or rearrange to a five- coordinate square pyramid (SP), 122. The cycle passing 122 is less probable than that passing 122 since the D-allylic metal intermediate (122) is more reactive than 6-allylic metal intermediate (122). The cycle from 112 to 121, the homolytic fission of hydrogen, would involve unlikely oxidation of palladium(II) to palladium(IV). As a matter of fact, reduction to palladium metal was always observed during the reaction. In order to understand the possible source of hydrogen for the formation of the metal hydride complex, the hydrogenation was tried in different conditions: (a) under H2 with acetone as solvent, (b) under H2 without solvent, (c) under Ar with solvent and (d) under Ar without solvent. The hydrogenation took place only in (a) and (b) with different degrees of conversions. This shows that, while molecular hydrogen and substrate may supply hydride ions, the solvent cannot be a significant source of hydrogen, at least under the high hydrogen pressure. One may expect that if solvent is not used in the hydrogenation, the monoene 163 yield will be reduced, was demonstrated with complex 66. When this complex was used as a catalyst, the monoene percentage dropped about half from 93% to 49%. In addition, the possibility of binuclear catalysis in the diene hydrogenation has not been excluded. 164 (b). Selective Hydrogenation of Conjugated 1,3-Cyclohexa- diene to Cyclohexene with Complexes (66, 62, 11, 12). The selective hydrogenation of 1,3-cyclohexadiene in acetone at room temperature and a 103 psi initial hydrogen pressure with complexes as catalysts was also examined in detail. Similarly, the products, cyclohexene and cyclohexane, were analyzed by gas chromatography and 1H NMR as discussed before. In Table 19 the turnover rate, induction time, and selectivities are dependent on different substituents on the cyclopentadienyl ring, whereas the percentages of cyclohexene and selectivities in all cases were much higher than those in the hydrogenation of 1,3- cyclooctadiene. It is evident from the preceding results that observed rates and products in hydrogenations catalyzed by palladium complexes depend on the ligands, the oxidation state of the central metal atom, substrates, solvents and other constituents of reaction mixtures. Of these, the nature of substrates appears to be most important and, in fact, determines the relative effect of other variables. Therefore, it can be assumed that the complexing of the substrate is an important step in the reaction sequences. It is evident that open-chain olefins are more likely to assume the proper arrangement for bonding to the metal than cyclic ones. Thus, open-chain dienes such as 1,7-octadiene are hydrogenated much faster than cyclic dienes such as 1,5- cyclooctadiene. It is also reflected in the general 165 Table 19. Hydrogenation of 1,3-Cyclohexadienea with 66, 58, 11 and 16 -- Effect of Catalysts. Catalyst Solvent Turnover Conver. Products(%) Select. /PdCl2 Rate (%) Monoene Alkane (%) sphc acetone 475.5 100 95.9 4.14 95.9 S(Ph-Cl)c acetone 665.5 100 94.8 5.16 94.8 SPhd acetone 249.5 100 97.0 3.05 97.0 S(pn-CI)d acetone 248.3 100 95.7 4.31 95.7 a: 7.45x10'3mole of substrate in 9 ml acetone. b: 2x10-Smole catalysts. c:(C5H -1-CH2NMe -2-SR)Fe(C5H4-SR)PdC12. d:(2,2)- (C H3-1-CHMeNMe2- -SR)Fe(CSfi4-SR)PdC12, at room temperature, 10; psi initial pressure. 166 observation that the rate of isomerization is much greater than the rate of hydrogenation. APPENDIX 168 .3.“ um .wIm. Mo .5590an m2: ma .Hq. muzmfim ELL I.& I. §.N §.n I.M S.w I. h I. m S. m 11413134111143.4133}. éJéqujiqdelfifiwé 169 .... ...... {1111.— ..IIIIII. .02 um .HM mo asuuommm mzz UmH .NH musmwm ELL 8m 8m Sr am am an JIIIIIJ.II.I.JI IIIIHI I _ _ _ _ 1 '7” f II . « fl? 3. 170 .um um .MN mo asuuommm mzz ma .mu musmwm ELL G.s §.~ §.N @.n §.r IafilflmaWfiTWfimWflnn1fi111fi1IL—«fi1l4111111IL—I1111##11al.1-fi11117 : 33% 171 @~ JI ELL .um um .MM no cauuomom mzz and .v2 unseat EN an at Sm Gm N; am am I In? .Idjjfjlli qIIII_Ir.III._IIIIJJ.IIII1III.IJIIIII_.IIII._JIIII1.II. _ 1 1 I3 1. 114 172 rbLL .HmId um .wM mo asuuommm mzz :H .mn muaofim 173 .umIm um .mIN no aauomam mzz UmH .3 0.5me TEL .95. E. E . Gm j 174 ELL .HAIH um .«M No Enuuommm mzz ma .na «Haven 175 .naIw um .«M «o eauuomem mzz one .eH ounoem L L am on or om : cm on em oIm I 55... A: I. 331.: 1 176 g I .H>usmIq um .WM no asuuommm mzz ma .ma uneven ELL 177 .amusmIq um .WM mo asuuowam mzz Una .om musoam rrLL E.&a E. Em . e. Em 8. En H444444444AJJJJj1Wflflflfln4ia444444444444444Hfifi15fifififififi444444444A4J44444444444444444H44444I Ja I: JJJH 4n Lfl J 3% 4 A _ 178 E . a Q. a m_.N Q.mu .ahusmIM um .MM Ho Bauuommm mzz ma .am musmah e-r :LLe.m e.m e.n e.m e.m . an»._pp._.___rwwprpppppp_p_pprp_p._r»___...p~p~pbppp.rhbrrrrnphrpvp_p_rbpppe_p__~__p—pp_~ppp.pp.r I4 . a 1:1 1 179 .aausme um .MM mo asuuommm mzz Una .mm madman 180 .axucmmId um .3 no aauommm 5.2 ma .nn ousmah ELL 86. &.a e.N &.n 8... Elm E.m nib &.m &.m 131... .333 E. 181 EH E.EN 8.8m fififififi44444444JJ11flflfifiA444JJJJI .azucmmIH um .ww wo Esauommm mzz Una .em musmam FELL nT_Er n5_em E._Bm E..ah e..um J. J J II. g —: j fififil 182 .ahcmcm um .wM uo asuuommm mzz :a .mm muzmam . PLLL nu.& NE a @.Mw &.Mu E.r nEmw E.mw E.~. _u.m E.mw 183 .ahcmnm um .wN mo asuuommm mzz Una .om musmam FELL .em NE Efi.~ E.nufl~ J I. 184 .amncmm um .dm Ho asuuomam mzz ma .nm musmam on 8.... e.~ on art“. on 5...... on on _ apart—FIFIPPPPFPI—Iaphp :PhP—Irrp — _I-pbrrcbappIappl—L_PPPIPIFppl—Ip _ a»: WP PIFIP: PpaahrI—Ihbbhphpap—-P:p-»I_ —LI 185 .Emu .Em gnaw .aaucmm um .qm mo asuuomam m2: Una .wm Gasman rrLL 8.8m 8.851 E.em~ PCFLFCFECFPTFFCF a A JgTJaIII 186 .aaaoeIe um .am no eanuomon mzz ma .mm «Hanan ELL on n... e.N an e... e.m e.m on on on Jfigfi lg! 187 N. . Em .aaaoeze an ..ad no souuumom 5.2 ona .on 8.53... ELL §.Bm E.Gaa MEN—fly 188 .noIaoIe um .mm no annuomon mzz ma .an ouamam ELL ea. e.. an on s... on on. e... on em FPHP—r—a-aFFPFFPr—pErr-rbrrrrrrP-PFFPPParr-aFprP.P—__——araprrpr—___pap—FPFPPPHP—_ar—PFP—_rp—_—prprr A I. _ 189 E.Efl 8. ED .noIquv um .Mm no eouuooon mzz ona .mn muomam ELL E. Em 4444 1L— 4 4 4 4 4I 44. 44.1 44. 4I 4I 4444an 4444. 444fl4 44. 44I 44I 4I Jr 4 4 44.4.4.44I4I_I4I4.4.4.4..444I—4I444444I4I4 144444444I—4 44 444 44 4 4 444 4 4444I_4 4 4 4.4 444 J 4I 4 J 4 J43 E .EnL J ; 4 190 .4scmco um .am no aauuomon mzz ma .nn anoman ELL Q.m E.m e.n e.m &.m FEE—.EEIFC 191 E . 8a .Snu .Bm .ahcmnm um .«w uo enhuommm m2: Una .wn musoah rrLL Q-.ah E. Sm“ P: 8.4uaa E..BHH EFF... _1. 4.3.! 192 .nmIaoIe um .wm no esuoomom mzz m4 .mn «human 8.8 5.4 e.N e.n e.r ELLe.m e.m e.o e.m e.m raprhapharrppl— FIPP-h-prh—P~_a»Farr—_-~_ppph—P_~__:P_thtthpP—pPpp-hp~—P»_P__p_~l—Irh::ppprh_ n 4.44 193 .Qm .amIaoIe um .mm no asuuooom mzz ona .on muamam can ELI. eém E.n:4 8.8m: J34 II— 194 Q.m_ ...... QIla rrLL .82 um .wm no asuuommm mzz :a .nn musmam e.m e.m en e.m on 195 .82 um .mm no 85448818 mzz ona .nn 845544 ELL §.§w §.§m §.®§a 196 EIIa IIMW .n EInu .um um .MN MO asuuommm mzz ma .mn «woman rrLL E.mw mfi.m 8.“. §.mw I. m JJJJAJJ4444444444444444444444444444444441111fi11 4444 197 on or am .um um .Mw mo souuomon «:2 Una .ov musoam ELL Gm 584. Em So am I_.IIII._J||._.IIII_IrIII4|IIJI I 4 44 III I I‘JI". _ ‘1'] 198 mine .umId um .dm mo asuuommm mzz ma .av Gunman akLL E.mw E.mw §.~. nu.m §.mw 4114333313143; 199 .umIQ um .dm mo Esuuommm mzz Una .mv «woman ELL &.ea E.En 8.8m 8.8h 8 am 4|14l1414J14I4lflJI4I1J14I1JWJI4IfiJ14I1J14I1J 4 44. 1 4 :4 1 2C”) .u .HmIH um .mw mo asuuommm «:2 :a .ne «macaw rrLL a... e.w e.m J aaaa—anfinaaaaafia:444444—44aaa4n1fiaa4a1aaa—411 201 .umIfl um .Nd no asuuommm mzz Una .eq «unmam ELL 8.8 G.§N 8.9.. mffim. §.§m §.®m: JWflWWnW-WWnWWqunfiaaWfifilfiTa 1—I1IJWl1w1fi11fi1111m1111fi14114111114 4 4 Q J J, 4II|J_I3. 202 .m .aausmId um .dfl no asuuommm mzz ma .mv mhsmam rrLL I.r _u.m mu.m I.m. _u.m &.mw .44444444441411. 33344444fi11333344444 203 .amuoan um .44 «0 aauuomon mzz ona .oe munmam rrLL §.§ 8.8N I.Gr §.Em §.@m §.Em: I1L—1fi11— 14 naL—lfiaa Wfiafi11wan11q4WWW—Ifi111flfi411wWWTHfinWTWLfiaW 1:. I j Jfi 1? 4 437437 Jnlllj 204 _xugm III - m o 0 v m -m m u .N e.n E... E. m B.m E .h E.m DEM 7. 44 205 .asuame um .44 no azuuooom m2: ona .ee munoam ELL G.m 8.8N &.Br §.§m 8.m_m §.@m:. 1 11fi1111fl1111w1111fi11 11.—1 J g .1 J A 14;... 206 .ahusmIH um .NIv. mo 4.3.30QO mzz :a .844 8.30am 8.8 8-4 8.N 8.... 8... :LL8.m 8.8 88 8.8 8.8 PEP?PPPPrIrbrbr.rrPr—VrrrP_rhyPPPPPPP—rFPrrbrPPPI—PPrPP+brPP—PrrPPr+rrPhrPP_PrPP rb’5P—{PPPLrtrP—rLblbrrk—DIL fl .a>H:MIM um .Mfl mo Esuuummm mzz Una .om musmam 207 FELL EN En Er em Eu Eh am an ELI--.:L::_:Irf :er-ILIL:IrETIrE.{ELI I4 I417 4JI 17 1 I1 1| 208 .aaucmmIfl um .N« no fisuuommm mzz ma .am musmam rrLL nu.& &.4. nu.N 8.4“ E.r. nfmw E.mw 8.“. nu.m a. allgfibt I41 1 209 .asucmeIa um .m« no 85448888 mzz ona .mm 885848 ELL 8.8 E.8N 8.84. 8.88 E 88 210 .axcmnm um .«d no asuuummm mzz ma .nm Gasman rrLL 33333333144471: 8.mw 8.a. 8.mw 48.8 . 4 44 211 .aacmcm um .«d mo Esauommm mzz Una .vm ousmam 2...... 8-84 8.8m 8.8m 8.8a 8 8m 8.8: 8.82 8.8V}. r {Si—33333373334344.1333): 4:11—4141414—4:4:144:11:1:14:44144414—4444114—444:111 12%}; 212 . N E . 8. .448588 um .88 no 55458888 522 :4 .mm 845544 ELL 8... e..m 8.48 at n 8.48 213 ..8N .Gr 95.8m .axncmm um .mfl no 85440888 m2: Una .om 849048 FPLL 8.488 n..n:84 8.48N4. .3714?in 8.8F.~ 214 . n .asaoeIe um .88 40 55448858 ms: :4 .48 845844 ELL . 8.m 8.8 8.4. 8.8 8 m 141—13.131174) ’ 215 8I8 8. 8N ,8f8r .aaaoeIe um .88 40 55448888 «:2 844 .88 845844 8.88 WIIIIJIJ ELL 8.8m 8-884 _ 8.8Na I5 8.8r4 L 441- 216 .znaIaUIv um .Nlm no 4544440898 fizz ma .mm 8.444848 ELL 217 .55I48Iv an .M8 4o 55448858 552 ona .oo 845844 CL... 884 8.8m 8.8m 8.85 8.88 8.844 8.82 IFFEP—ppbppz::L:::P:I_1::::_—::pp—IHP—ZCrap—p—EEE-F—ECLEPCb—CI—Ippppppp:_—:—:_Papr—E—E—a::::_:::_:_:::: 218 8 —rrr?FrPPr—FPrPPP?P 8a SN r’lrrp'lrr’ En. PDPPPDDVD» Er 8m .82 um .Md no 55440858 mzz Una .am 845845 PLLL Eu 84. 88 an 884 r+PPPrr’?—rPrr.—{rrrb¥ Prrrbrr’r8—Dlrrrbrrrrr rrr?—VrblPr.rrr?Pr?’P.vaP? ‘ g4 4 J{lfilllll#fi .J I. fijjfifl 219 .Efi .hun .Em. .Hanmnm um .Nfl no sauuommm mzz UmH .~o musmwm PFLL mfnur 8.5Em n5.8~.~ 8.8ufl~ Egg? 1.3: 4 J4} 220 .nmuflu; um .3 no afiuommm 6.2 2H .8 3ng ELL e.& &.A e.N e.n a... e.m gm e.h EJm gm PPP—PPPPPPPFP—FPPPPPPPP—PP—PP—prr—Prppphrbrbbprppppprb%prppphhp—~PPP~PPPFP%P~__~_PP—Pppppr-FHPrr \ 221 Q.m: NTEU E.Em .nmuaoav um .qw no asuuooam mzz Una .eo musmfim ELL E. Eh E.Gm E.n.:~ E.En# EEC—SPELEEELEEEE._CEZELE_Z:LEEZF—E EETEEEPEZ:ZLFZZIF»:ZZZ—:2.5P5:— _E—EF JJ J14 4a J % 222 nu.a E..~ E.mw S.mm E.r. .Hhcmnm um .mw no asuaummm mzz ma .mm musofim. «ELL E.mw m_.m 8.“. §.mw §.mw Fr:—Prb—PFPPFFFFPF~ PP—PPFPrppPr—PPPPFPPPP—P:: _P— P—rrrrbpVHF—PPPFPPFPPFPPprprppPPPPPPPPPP—FP J 3% 223 .Haaoeuv um .Mw no aauuommw mzz ma .oo unamwm as a; s.~ sh ng. Fina. um n4. 9m ah Prrp—Prrrrrrpr—PPFFP—PrP—rrrrrrP—P—P—PPP—PPPFPPPP_P—Pp—FPPPPPPPPPPPPPPPPPP—PPP—p—PPr—Perppp—FPPP Jé 224 .nmuaouv um .mm no azuuommm mzz mfl .hm ausmflm ELL 8.: a; e.~ e.n 8... gm ed. QB e.m eh [Pip PP—rprrp _ PPr—y—PPPP— FPP—PPPPFPPPP—Pr PPPPEF:PP_ PPPPFPPPPPCPP _VPPPPFFPPLUFPPF —_PFFFPFPP PPPPPl—IPPP 225 .Hhcmnm um .dN no sauuommm as: :H .mm «known FELL nu.@ mi 9 mu.N 8.mu &.r‘ §.mw m=.m .u.~. §.mw 8.mw PPFPPFPPPPPPP r.— FErFFPPrp—P P— PPPFPP— FPPPPPFFPTPPPP: P P—Prrrrrrrerrrrrrprr—PPF Prrr PFFPPPPPFPFP— Pr 226 n . .Hwaoang um .mM no sauuomam mzz a” .mo ousofim an: am am as u.m 227 .zmlnuiV um ..WM mo Bauuommu mzz :H .on muamfim. ELL §.& n.~ E.N §.m.. 8;» &.m ®.m §.h §.m E.m _rPP — FPFPFPFFP— FTPFPP PPFPFPPPFPPFF—PFPFFFFPPFFFFPPFP — FPPPPPPFFFPFPPPCF—FPP p _ Pp p P—P PPPPPPPF—PPF 47 fl REFERENCES 10 11 12 13 14 15 REFERENCES Morrison, J.D.; and Mosher, H.S. "Asymmetric Organic Reactions". Prentice-Hall Englewood, Cliffs, New Jersey, 1971. 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