Asymmetric conjugate reduction of alpha,beta-unsaturated ketones and esters with chiral rhodium(2,6-bisoxazolinylphenyl) catalysts.
New asymmetric conjugate reduction of beta,beta-disubstituted alpha,beta-unsaturated ketones and esters was accomplished with alkoxylhydrosilanes in the presence of chiral rhodium(2,6-bisoxazolinylphenyl) complexes in high yields and high enantioselectivity. (E)-4-Phenyl-3-penten-2-one and (E)-4-phenyl-4-isopropyl-3-penten-2-one were readily reduced at 60 degrees C in 95 % ee and 98 % ee, respectively, by 1 mol % of catalyst loading. (EtO)2MeSiH proved to be the best hydrogen donor of choice. tert-Butyl (E)-beta-methylcinnamate and beta-isopropylcinnamate could also be reduced to the corresponding dihydrocinnamate derivatives up to 98 % ee.
Kanazawa
Yoshinori
Y
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan.
Tsuchiya
Yasunori
Y
Kobayashi
Kazuki
K
Shiomi
Takushi
T
Itoh
Jun-ichi
J
Kikuchi
Makoto
M
Yamamoto
Yoshihiko
Y
Nishiyama
Hisao
H