Copper-catalyzed regiospecific synthesis of N-alkylbenzimidazoles

A copper-catalyzed method is described for the preparation of N-alkylbenzimidazoles in regioisomerically pure form starting from o-haloanilines. The method utilizing CuI and trans-N,N'-dimethyl-1,2-cyclohexanediamine allows the preparation of N-alkylbenzimidazoles in good to excellent yields.