Radical Trifluoromethylative Dearomatization of Indoles and Furans with CO₂

Abstract

Disclosed herein is a versatile and practical strategy for catalytic radical dearomatization. By means of this strategy, we realized the trifluoromethylative dearomatization of indoles and furans with CO2 via Cu catalysis. We also demonstrated the dearomatization of indoles with C-3 C–O bond formation to generate spirocyclic indolines. A variety of important CF3-containing spirocyclic indolines and spiroacetals can be synthesized with atmospheric CO2 under mild reaction conditions. Moreover, these multicomponent reactions feature high selectivity, good functional group tolerance, broad substrate scope, and easy scalability. Further theoretical investigation indicates that this transformation starts with deprotonation of the amine and CO2 insertion, after which CF3· radical addition to the indole followed by intramolecular C–O coupling affords the oxazolidone product.