Asymmetric Intermolecular Stetter Reactions of Aromatic Heterocyclic Aldehydes with Arylidenemalonates

The asymmetric Michael addition of aromatic heterocyclic aldehydes to arylidenemalonates catalyzed by N-heterocyclic carbenes is described. The ketomalonates are obtained in 84-98% yields and moderate to good enantioselectivities (30-78% ee). The enantiomeric excesses Could be improved to excel lent levels of Lip to 99% ee after a single recrystallization.