Catalytic C[sbnd]H activation-initiated transdiannulation: An oxygen transfer route to ring-fluorinated tricyclic γ-lactones

Abstract

Catalytic CH activation-initiated annulation reactions have emerged as a versatile strategy for the efficient construction of diverse ring structural units and complex cyclic molecules in synthetic chemistry. Herein, we describe a new Rh(III)-catalyzed CH activation-initiated transdiannulation reaction of N,N-dimethyl enaminones with gem-difluorocyclopropenes in the presence of H2O, enabling a facile and oxygen transfer access to ring-fluorinated tricyclic γ-lactones with a 6-5 ring-junction tetrasubstituted stereocenter. This approach features bond-forming/annulation efficiency, good functional group tolerance and complete regioselectivity, which may include a complex process consisting of Rh(III)-catalyzed C(sp2)H activation, cyclic alkene insertion, defluorinated ring-opening of gem-difluorocyclopropane, intramolecular oxygen transfer, intramolecular cyclization and oxidative hydration.