Trihaloisocyanuric Acids in Ethanol: An Eco-Friendly System for the Regioselective Halogenation of Imidazo-heteroarenes

Herein, we describe an efficient, rapid and benign protocol for the direct C(sp(2))-H bond halogenation (Cl, Br, I) of 2-arylimidazo[1,2-a]pyridines using trihaloisocyanuric acids in ethanol. Furthermore, this sustainable protocol was successfully extended to imidazopyrimidine, imidazothiazole and indazole heterocycles showing the broadness of this useful approach.