Copper(II)-Catalyzed Direct C3 Chalcogenylation of Indoles

3-Chalcogenylindoles serve as crucial building blocks in organic synthesis and pharmaceutical chemistry. Herein, we describe a simple and general synthesis of 3-chalcogenylindoles through the direct C-H chalcogenation of indoles using N-selenophthalimide and N-sulfenylsuccinimide as chalcogenation reagents in the presence of CuBr₂ as the catalyst. The reactions were carried out in CH₂Cl₂ at room temperature under an air atmosphere with a low loading of catalyst, and a wide range of 3-selenylindoles and 3-thioindoles were obtained in good yields. Various functionalities, namely, methyl, methoxy, halo, ester, cyano, trifluoromethyl, and formyl groups on indoles, have shown amenability to the developed reaction. A mechanism involving the activation of the chalcogenation agent through CuBr₂ coordination with the amide carbonyl group is proposed.