Chemoselective Chan-Lam Coupling Reactions between Benzimidazoline-2-thiones and Arylboronic Acids.

An efficient Chan-Lam-type methodology for the selective synthesis of S-arylbenzimidazoles and N,S-diarylbenzimidazoles was developed. The selectivity was controlled by varying the amount of the catalyst Cu(OAc)2·H2O, temperature, and solvent switching. These transformations feature a simple protocol, broad functional group tolerance, high selectivity, and good to excellent yields. It is noteworthy that these reactions represent the first examples of the application of the selective Chan-Lam coupling.