Practical chemoselective aromatic substitution: the synthesis of N -(4-halo-2-nitrophenyl)benzenesulfonamide through the efficient nitration and halogenation of N -phenylbenzenesulfonamide.

A novel route involving the metal-promoted tandem nitration and halogenation of N -phenylbenzenesulfonamide to synthesize N -(4-halo-2-nitrophenyl)benzenesulfonamide derivatives has been developed. The method shows highly practical chemoselective and functional group compatibility. In addition, it employs insensitive and inexpensive Cu(NO 3 ) 2 ·3H 2 O, Fe(NO 3 ) 3 ·9H 2 O, and NH 4 NO 3 as the nitration reagents, and it provides a direct approach for the preparation of 4-halo-2-nitroaniline, which is a crucial intermediate for the synthesis of benzimidazoles and quinoxaline derivatives.