Trifluoroethylation of Alkynes: Synthesis of Allylic‐CF 3 Compounds by Visible‐Light Photocatalysis

Two types of allylic trifluoromethylated compounds were synthesized by reacting alkynes with CF 3 CH 2 I using visible‐light photocatalysis. Subtle differences in the catalytic system controlled the selectivity of iodotrifluoroethylation and hydrotrifluoroethylation. The iodotrifluoroethylated products were obtained in the presence of [Ru(bpy) 3 ]Cl 2 and TMEDA in CH 3 CN under visible‐light irradiation, whereas hydrotrifluoroethylated products were synthesized using fac ‐[Ir(ppy) 3 ] and a mixture of DBU and K 2 CO 3 in DMF. The iodotrifluoroethylation reaction worked particularly well, even at gram‐scale, and the synthetic utility of iodotrifluoroethylated products was proved by their coupling reactions, providing complex CF 3 ‐containing products.