Asymmetric Organocatalyzed Cyclization Cascade Reactions of 3,3-Difluoro-2-aryl-3H-indoles and Enamides

The direct functionalization of beta-C-(sp(2))-H bonds in enamides has garnered increasing attention within the realm of organic synthesis. However, these remarkable advancements are predominantly dependent on transition metals; limited success has been achieved via organocatalytic catalysis. Herein, we report a CPA-catalyzed beta-C-(sp(2))-H functionalization of enamides cascade intramolecular cyclization to synthesize the chiral dihydropyrimido-[1,6-a]-indoles bearing gem-difluoromethylene. Moreover, this methodology enables the synthesis of diverse chiral dihydropyrimido-[1,6-a]-indoles with outstanding enantioselectivities in moderate to high yields.