Asymmetric Organocatalytic Reductive Coupling Reactions between Benzylidene Pyruvates and Aldehydes

An organocatalytic three-component reductive coupling reaction between dimethyl phosphite, benzylidene pyruvates, and aldehydes is reported. A chiral triaryliminophosphorane catalyst promotes Pudovik addition, which is followed by phospha-Brook rearrangement to transiently generate enolates that are trapped stereoselectively by aldehydes. This reductive coupling provides vicinal polyfunctionalized stereocenters from readily available pro chiral starting materials with excellent diastereoselectivity, enantioselectivity, and yield.