Direct Photoassisted α‐Trifluoromethylation of Aromatic Ketones with Trifluoroacetic Anhydride (TFAA)

Abstract Direct α‐Trifluoromethylation of acetophenone derivatives was achieved by using trifluoroacetic anhydride (TFAA) as the trifluoromethyl source and pyridine‐ N ‐oxide (Py−O) as activator and oxidant under visible light irradiation and tris‐(2,2′‐bipyridine)ruthenium(II) hexafluorophosphate (Ru(bpy) 3 (PF 6 ) 2 ) as the photocatalyst. Different acetophenone derivatives could be converted to the corresponding α‐CF 3 derivatives with high selectivity. Extensive mechanistic investigation revealed the formation of vinyl trifluoroacetate as the key intermediate for this transformation. magnified image