Radical C(sp²)–H Trifluoromethylation of Aldehydes in Aqueous Solution

The copper-mediated C(sp²)-H trifluoromethylation of aldehydes is described. The reaction of aldehydes with (bpy)Cu(CF₃)₃, Et₃SiH, and K₂S₂O₈ in aqueous acetone at room temperature provides the corresponding trifluoromethyl ketones in satisfactory yields. The protocol is applicable to both aliphatic and aromatic aldehydes and exhibits a broad substrate scope and wide functional group compatibility. A mechanism involving Cu(II)-mediated trifluoromethylation of acyl radicals is proposed.