Asymmetric Direct Vinylogous Conjugate Addition of Substituted Furanone Derivatives to Benzoyl Acrylonitrile: Stereoselective Synthesis Toward Bicyclic γ-Lactams

A diaminomethylenemalononitrile organocatalyst efficiently promotes the asymmetric direct vinylogous conjugate additions of alpha-angelica lactones to benzoyl acrylonitrile derivatives, resulting in the corresponding addition products bearing vicinal tertiary and quaternary stereogenic centers with excellent enantioselectivities (up to 99% ee). This report is the first successful example of the asymmetric conjugate additions of alpha-angelica lactone to benzoyl acrylonitriles. The chiral gamma,gamma-disubstituted gamma-butenolides obtained can be readily transformed to the bicyclic gamma-lactam derivative as a valuable synthetic intermediate.