Chiral Tetraaminophosphonium Carboxylate-Catalyzed Direct Mannich-Type Reaction

The cooperative asymmetric catalysis of chiral tetraaminophosphonium carboxylate (P,S)-1-OCOR has been established, and its synthetic utility has been successfully demonstrated by application to the highly enantioselective direct Mannich-type reaction of azlactones with N-sulfonyl imines. The present study stimulates the cultivation of the potential of the chiral quaternary onium salt catalysis by the structural modification of organic anion.