Heterogeneous Asymmetric Reduction of Ketimines with Trichlorosilane

Significance

Asymmetric reduction of ketimines 3 with trichlorosilane was catalyzed by polymer-supported N-methylvaline derived formamides (1 and 2). Thus, the reaction of 3 (4.44 mmol) with trichlorosilane was carried out in the presence of the Merrifield resin supported catalyst 1 or 2 in CHCl₃ to give the corresponding amines 4 in 62-82% yield with 76-82% ee. The catalysts 1 and 2 were reused five times without any loss of catalytic activity.