Copper-mediated trifluoromethylation of arylboronic acids by trifluoromethyl sulfonium salts

The ligand-free trifluoromethylation of arylboronic acids with a [Ph2SCF3](+)[OTf](-)/Cu(0) system has been carefully investigated. Aryl-, alkenyl- and heteroarylboronic acids with a variety of functional groups were suitable substrates for this reaction. It is suggested that a CuCF3 species is formed under the reaction conditions.