Copper-catalyzed thiolation of imidazo[1,2-a]pyridines with (hetero)aryl thiols using molecular oxygen

A new and facile copper-catalyzed thiolation of imidazo[1,2-a]pyridines with (hetero)aryl thiols was developed for the formation of C–S bond by using molecular oxygen as oxidant under base-free conditions. The presented protocol has provided the selective C-3 sulfenated products with good yield. A computational study was carried out by using the B3LYP density functional theory to elucidate the regioselectivity of C-2 and C-3. Calculation results indicated that the thiolation toward C-3 was easier and smoother, which was consistent with our experiment results.