Copper(II)-Catalyzed Selective C_Ar-H Bond Formylation: Synthesis of Dialdehyde Aniline

A simple and efficient method for the synthesis of dialdehyde aniline in good yields (up to 83%) is explored using Cu(OTf)₂ as the catalyst, Selectfluor as the radical initiator, and DMSO as both the carbon and oxygen sources. Experimental studies indicate that the reaction is achieved by the formylation of two C_Ar-H bonds, first at the para-position and then at the ortho-position. A possible mechanism is proposed, including the thermal homolysis of Selectfluor, the Cu(II)-facilitated formylation of the C_Ar-H bonds, and the hydrolysis of the amide under alkaline conditions in air atmosphere.