Polymer-supported organocatalysts: Asymmetric reduction of imines with trichlorosilane catalyzed by an amino acid-derived formamide anchored to a polymer

Asymmetric reduction of ketimines 1a-e with trichlorosilane can be catalyzed by the N-methylvaline-derived Lewis basic formamide anchored to a polymeric support (5a and 5b) with good enantioselectivity (<= 82% ee) and low catalyst loading (typically 15 mol %) at room temperature. This protocol represents a considerable simplification of the isolation procedure and is particularly suitable for a parallel synthesis of chiral amines 2a-e. The polymer-supported catalysts retain full activity after a multiple use.