Copper-Catalyzed Selenylation of Imidazo[1,2-a]pyridines with Selenium Powder via a Radical Pathway.

A convenient and efficient approach for the formation of nitrogen heterocycle-fused imidazo[1,2-a]pyridine and benzo[b]selenophenes has been developed through copper-catalyzed direct selenylation of readily available 2-(2-bromophenyl)imidazo[1,2-a]pyridines via regioselective cleavage of C(sp2)-Br and C(sp2)-H bonds using readily available selenium powder as the selenylating reagents under ligand- and base-free conditions in air. Preliminary mechanistic investigations indicated that radical species were involved in the present transformation.