Cathodic C-H Trifluoromethylation of Arenes and Heteroarenes Enabled by an in Situ-Generated Triflyltriethylammonium Complex

While several trifluoromethylation reactions involving the electrochemical generation of CF3 radicals via anodic oxidation have been reported, the alternative cathodic, reductive radical generation has remained elusive. Herein, the first cathodic trifluoromethylation of arenes and heteroarenes is reported. The method is based on the electrochemical reduction of an unstable triflyltriethylammonium complex generated in situ from inexpensive triflyl chloride and triethylamine, which produces CF3 radicals that are trapped by the arenes on the cathode surface.