Organo[2-(hydroxymethyl)phenyl]dimethylsilanes as mild and reproducible agents for rhodium-catalyzed 1,4-addition reactions.
Stable and reusable tetraorganosilicon reagents, alkenyl-, aryl-, and silyl[2-(hydroxymethyl)phenyl]dimethylsilanes, undergo 1,4-addition reactions to alpha,beta-unsaturated carbonyl acceptors under mild rhodium-catalysis. The reaction tolerates a diverse range of functional groups and is applicable to gram-scale synthesis. Use of a chiral diene ligand allows the achievement of the corresponding enantioselective transformations using the tetraorganosilicon reagents, providing the silicon-based approach to optically active ketones and substituted piperidones that serve as synthetic intermediates of pharmaceuticals. A rhodium alkoxide species is suggested to be responsible for a transmetalation step on the basis of the observed kinetic resolution of a racemic chiral phenylsilane in the enantioselective 1,4-addition reaction under the rhodium-chiral diene catalysis.
Nakao
Yoshiaki
Y
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan. nakao@npc05.kuic.kyoto-u.ac.jp
Chen
Jinshui
J
Imanaka
Hidekazu
H
Hiyama
Tamejiro
T
Ichikawa
Yoshitaka
Y
Duan
Wei-Liang
WL
Shintani
Ryo
R
Hayashi
Tamio
T