The efficient enantioselective synthesis of dihydropyrans via organocatalytic Michael addition reactions

Abstract

An asymmetric Michael addition of α-cyanoketones to α,β-unsaturated aldehydes to form chiral dihydropyrans catalyzed by l-diphenylprolinol trimethylsilyl ether is presented. A series of 3,4-dihydropyrans were obtained in excellent yields (up to 91%) and enantioselectivities (up to 98% ee). A plausible mechanism for this process is proposed.