The synthesis of substituted benzimidazoles, 2-aminobenzimidazoles, 2- aminobenzothiazoles, and benzoxazoles is described via intramolecular cyclization of o- bromoaryl derivatives using copper (II) oxide nanoparticles in DMSO under air. The procedure is experimentally simple, general, efficient, and free from addition of external chelating ligands. It is a heterogeneous process and the copper (II) oxide nanoparticles ...