Asymmetric hydrogenation of α,β-unsaturated phosphonates with Rh-BisP* and Rh-MiniPHOS catalysts: Scope and mechanism of the reaction

doi:10.1073/pnas.0306993101

Asymmetric hydrogenation of α,β-unsaturated phosphonates with Rh-BisP* and Rh-MiniPHOS catalysts: Scope and mechanism of the reaction

^†Department of Chemistry, Faculty of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan; ^‡COE Laboratory, Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan; and ^¶Department of Chemistry, Moscow State University, Moscow 119899, Russia

Edited by Jack Halpern, University of Chicago, Chicago, IL, and approved December 17, 2003 (received for review October 28, 2003)

Abstract

Optically active 1,2-bis(alkylmethylphosphino)ethanes and bis(alkylmethylphosphino)methanes are unique diphosphine ligands combining the simple molecular structure and P-stereogenic asymmetric environment. This work shows that these ligands exhibit excellent enantioselectivity in rhodium-catalyzed asymmetric hydrogenation of α,β-unsaturated phosphonic acid derivatives. The enantioselective hydrogenation mechanism elucidated by NMR study is also described.

Footnotes

↵ § To whom correspondence should be addressed. E-mail: imamoto{at}faculty.chiba-u.jp.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: BisP*, (S,S)-1,2-bis(alkylmethylphosphino)ethanes (alkyl = tert-butyl, 1,1-diethyl propyl, 1-adamantyl, 1-methylcyclohexyl, cyclohexyl, cyclopentyl, and isopropyl); MiniPHOS, (R,R)-bis(alkylmethylphosphino)methanes (alkyl = tert-butyl, cyclohexyl, isopropyl, and phenyl); ee, enantiomeric excess.
↵ ∥ Mikolajezyk, M., Drawbowicz, J. & Kielbasinski, P. (1996) J. Stereoselective Synth. 9, 570A.