The application of poly(N, N′-dibromo-N-ethyl-benzene-1,3-disulfonamide) and N, N, N′, N′-tetrabromobenzene-1,3-disulfonamide as catalysts for one-pot synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzimidazoles and 1,5-benzodiazepines, and new reagents for synthesis of benzimidazoles |