Cobalt-catalyzed carbon–sulfur/selenium bond formation: synthesis of benzo[b]thio/selenophene-fused imidazo[1,2-a]pyridines

An efficient cobalt-catalyzed C-S/C-Se bond formation method for the synthesis of benzo[b]thio/selenophene-fused imidazo[1,2-a]pyridines has been developed. This protocol was catalyzed by an inexpensive and commercially available cobalt catalyst without an extra reductant while using thiocyanate and selenocyanate as the sulfur and selenium sources. A wide range of benzo[b]thio/selenophene-fused imidazo[1,2-a]pyridines were obtained in good yields.