Photoorganocatalytic trifluoromethylation of (het)arenes in green conditions.

A sustainable photocatalytic protocol for the trifluoromethylation of (hetero)arenes is reported. The method operates under metal- and base-free conditions using an inexpensive and atom-efficient CF3 source, trifluoroacetic anhydride, in ethyl acetate as a green solvent. An organic cyanoarene photocatalyst enables efficient CF3 radical generation under blue-light irradiation, providing a broad range of trifluoromethylated arenes and heteroarenes. The reaction displays pronounced sensitivity to substituent patterns rather than electronic effects. Mechanistic investigations, including radical trapping, Stern-Volmer analysis, and DFT calculations, support a reductive quenching pathway involving photocatalyst-mediated reduction of TFAA. The protocol is amenable to scale-up, with continuous-flow operation delivering a significant increase in space-time yield, highlighting its potential for sustainable synthesis of CF3-containing molecules.