High performance of Rh(Phebox) catalysts in asymmetric reductive aldol reaction: high anti-selectivity.
Chiral rhodium(bisoxazolinylphenyl) complexes (1 mol %) efficiently catalyze the asymmetric reductive aldol reaction of aldehydes and alpha,beta-unsaturated esters at 50 degrees C for ca. 0.5-1.0 h with several hydrosilanes to give the corresponding beta-hydroxypropionates with extremely high anti-selectivity (up to 98%) and enantioselectivity (up to 96% ee). The stereochemical outcome is likely due to a chairlike cyclic transition state involving rhodium-(E)-enolate.
Nishiyama
Hisao
H
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan. hnishi@apchem.nagoya-u.ac.jp
Shiomi
Takushi
T
Tsuchiya
Yasunori
Y
Matsuda
Isamu
I