Merrifleld Resin Supported Dipeptides: Efficient and Recyclable Organo-catalysts for Asymmetric Aldol Reactions under Neat Reaction Conditions

摘要

A number of Merrifield resin supported dipeptide and tripeptide catalysts have been developed of which Pro-Ala-O-P, catalyst A, was found to be an efficient catalyst for asymmetric direct aldol reactions. Aldehydes and ketones underwent smooth aldol reaction in the presence of a catalytic amount of A at room temperature under neat reaction conditions and generated the corresponding products with excellent isolated yields (<98%), good diastereoselectivities (dr < 90:10) and enantioselectivities (<95% ee),, In addition, catalyst A could be used seven times without loss of its catalytic activity.