Cooperative and Enantioselective NbCl5/Primary Amine Catalyzed Biginelli Reaction

A series of chiral organocatalysts and Lewis acids have been evaluated in the Lewis acid/organocatalysts‐based cooperative catalytic Biginelli reaction, which resulted in the determination of a novel cooperative Lewis acid/primary amine catalyst system, NbCl5/QN‐NH2. The synergistic effect of NbCl5 and the quinine‐derived primary amine is pronounced and gave dihydropyrimidiones (DHPMs) in moderate to good enantioselectivities (up to 84 % ee) and good to excellent yields (up to 99 % yield) under mild conditions. A novel cooperative Lewis acid/primary amine catalyst system, NbCl5/QN‐NH2, was found to be an effective promoter in the asymmetric Biginelli reaction. Good enantioselectivities (up to 84 %ee) were obtained in this reaction.