Bi-Catalyzed Trifluoromethylation of C(sp)-H Bonds under Light.

We disclose a Bi-catalyzed C-H trifluoromethylation of (hetero)arenes using CFSOCl under light irradiation. The catalytic method permits the direct functionalization of various heterocycles bearing distinct functional groups. The structural and computational studies suggest that the process occurs through an open-shell redox manifold at bismuth, comprising three unusual elementary steps for a main group element. The catalytic cycle starts with rapid oxidative addition of CFSOCl to a low-valent Bi(I) catalyst, followed by a light-induced homolysis of Bi(III)-O bond to generate a trifluoromethyl radical upon extrusion of SO, and is closed with a hydrogen-atom transfer to a Bi(II) radical intermediate.