Aryl Sulfonium Salts for Site-Selective Late-Stage Trifluoromethylation

Abstract

Incorporation of the CF₃ group into arenes has found increasing importance in drug discovery. Herein, we report the first photoredox-catalyzed cross-coupling of aryl thianthrenium salts with a copper-based trifluoromethyl reagent, which enables a site-selective late-stage trifluoromethylation of arenes. The reaction proceeds with broad functional group tolerance, even for complex small molecules on gram scale. The method was further extended to produce pentafluoroethylated derivatives.

Keywords: late-stage C−H functionalization; photoredox catalysis; site selectivity; sulfonium salts; trifluoromethylation.