A versatile new synthesis of organic compounds with chiral methyl groups: stereochemistry of protolytic rhenium-carbon bond cleavage in chiral alkyl complexes (.eta.5-C5H5)Re(NO)(PPh3)(R) Academic Article uri icon

abstract

  • Reaction of (77 5 -C 5 H 5 )Re(N0)(PPh3)(C0 2 CH 3 ) (1) with (3,5-dimethoxyphenyl)magnesium iodide gives 3,5-di-methoxybenzoyl complex (T? 5 -C 5 H 5 )Re(NO)(PPh 3 )(CCK3,5-C 6 H 3 (OCH3) 2 )) (2, 97%). Reaction of 2 with BH 3 THF gives 3,5-dimethoxybenzyl complex (T? 5 -C 5 H 5 )Re(NO)(PPh3)(CH 2 (3 ) 5-C 6 H3(OCH 3 ) 2 )) (3, 86%). Reaction of 3 with Ph 3 C + PF 6 at -80 C gives a 62:38 mixture of the sc and ac Re=C geometric isomers (4k, 4t) of 3,5-dimethoxybenzylidene complex [(i7 5 -C 5 H 5 )Re(NO)(PPh 3 )(CFf(3,5-C 6 H 3 (OCH 3 ) 2 ))] + PF 6 '; workup gives 4t (89%). Reaction of 4t with Li(C 2 H 5 ) 3 BD or NaBD 4 gives addition product (SS,RR)-3-a-dy Optically active (H-H^)-! and (-)-(/?)-l (>98% ee) are similarly treated with (3,5-dimethoxyphenyl)magnesium iodide, BD 3 .THF, and Ph 3 C + PF 6 ' to give (+)-(S)- and (-MT^^t-a-^. Addition of NaBT 4 gives (+)-(SS)- and ()-(RR)-3-a-d1t1. Reaction with HBr gives (5 1 )- and (/^-dimethoxytoluene-a-^f!, and (+)-(/?)-and (-)-(5)-(77 5 -C 5 H 5 )Re(NO)(PPh 3 )(Br) (retention of configuration at carbon and rhenium). The former are treated with 0 3 to give chiral acetate salts (5)- and (/?)-CFIDTCOO _ Na + of 93% and 86% ee, as established by an enzymatic assay. The mechanisms of these transformations, and the utility of this route to chiral acetic acid, are discussed. 1987, American Chemical Society. All rights reserved.

published proceedings

  • Journal of the American Chemical Society

author list (cited authors)

  • O'Connor, E. J., Kobayashi, M., Floss, H. G., & Gladysz, J. A.

citation count

  • 40

complete list of authors

  • O'Connor, Edward J||Kobayashi, Motomasa||Floss, Heinz G||Gladysz, JA

publication date

  • August 1987