Copper Continues To Advance Trifluoromethylation

Copper-promoted trifluoromethylation reactions have been successful during the past three years, and researchers continue to broaden the scope of the chemistry and streamline procedures. Vladimir V. Grushin and coworkers at the Institute of Chemical Research of Catalonia, in Spain, now report a new synthesis of α-trifluoromethylated ketones (J. Am. Chem. Soc., DOI: 10.1021/ja307783w). They used CuCF₃, which they make from CuCl and fluoroform (CHF₃), a process Grushin’s group invented last year. Fluoroform is an inexpensive side product of polytetrafluoroethylene production, and the ability to use it in trifluoromethylations has opened the way to affordable large-scale use of CuCF₃. Grushin’s team previously used CuCF₃ to trifluoromethylate aryl halides and aryl boronic acids. In the current work, the researchers synthesized two dozen α-trifluoromethylated aryl and aliphatic ketones. In other CuCF₃ chemistry, Melanie S. Sanford and coworkers at the University of Michigan report a mild, easy method for trifluoromethylation of aryl boronic acids (Org. Lett., DOI: 10.1021/ol3022726). They used CuCl with NaSO₂CF₃ (Langlois’ reagent) and tert-butyl hydroperoxide, which react in situ under ambient conditions to create trifluoromethyl radicals. Sanford’s team used the system to prepare a range of easily purified aryl and heteroaryl trifluoromethyl derivatives.