Reactivity-Controlled Regioselectivity: A Regiospecific Synthesis of 1,2-Disubstituted Benzimidazoles

We demonstrate exceptional levels of regioselectivity in the tandem amination reactions between 1,2-differentiated dihaloarenes and N-substituted amidines. The regiochemical outcome of this CuI-catalyzed reaction is achieved through a combination of N 1 /N 2 chemoselectivity on the amidine and reactivity-controlled X 1 /X 2 chemoselectivity on the 1,2-dihaloarene. This reaction proves to be fairly general for the regiospecific synthesis of 1,2-substituted benzimidazoles.