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

The direct functionalization of β-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 β-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.