A Cation-Directed Enantioselective Sulfur-Mediated Michael/Mannich Three-Component Domino Reaction involving Chalcones as Michael Acceptors

A new approach has been developed for an asymmetric sulfur-mediated three-component intermolecular Michael/Mannich domino reaction using chalcones as Michael acceptors. This reaction is catalyzed by chiral quaternary ammonium salts derived from modified quinine and provides facile access to complex sulfur-containing compounds with three contiguous stereogenic centers in yields of up to 93%, with 95:5 dr and 95% ee. These compounds were further elaborated to give the equivalent of a chiral aza-Morita-Baylis-Hillman reaction involving chalcones and azetidines bearing four chiral centers.