Copper-Mediated Trifluoromethylation of Benzylic Csp -H Bonds.

Trifluoromethyl-containing compounds play a significant role in medicinal chemistry, materials and fine chemistry. Although direct C-H trifluoromethylation has been achieved on Csp -H bonds, direct conversion of Csp -H bonds to Csp -CF remains challenging. We report herein an efficient protocol for the selective trifluoromethylation of benzylic C-H bonds. This process is mediated by a combination Cu -CF species and persulfate salts. A wide range of methylarenes can be selectively trifluoromethylated at the benzylic positions. A combination of experimental and theoretical mechanistic studies suggests that the reaction involves a radical intermediate and a Cu -CF species as the CF transfer reagent.