Direct remote Csp2–H transformation of aromatic amines enabled by organophotoredox catalysis

Abstract

Despite the importance of difluoromethylene fragments in medicine, agrochemistry, and materials science, the precise and sustainable C–H difluoromethylation of aryl rings remains a challenge. Studies of metal-free difluoromethylation at room temperature would be advanced if methods were as reliable and modular as metal catalysis. Herein, we present a green and environmentally friendly modular platform for the sustainable para-difluoromethylation of readily available aromatic amines via a metal-free photocatalytic system. The reaction, for the first time, exhibits excellent functional group tolerance and broad substrate scope with a radical–radical coupling C–H functionalization strategy, rapidly delivering a variety of valuable difluoromethylated products. Furthermore, the derivatization of various complex molecules with high atom economy further demonstrates the synthetic utility and practicality of this protocol. A series of experimental studies and DFT calculations corroborate the plausible reaction mechanism.