Cooperative and Enantioselective NbCl₅/Primary Amine Catalyzed Biginelli Reaction

Abstract

Abstract 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, NbCl 5 /QN‐NH 2 . The synergistic effect of NbCl 5 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.