Tandem Flavin-Iodine-Catalyzed Aerobic Oxidative Sulfenylation of Imidazo[1,2-a]Pyridines with Thiols

A green, aerobic sulfenylation of imidazo[ 1,2-a]pyridines was performed using thiols, a flavinand- iodine dual catalytic system, and environmentally benign molecular oxygen as the only sacrificial reagent. The dual metal-free catalysts smoothly promote a unique stepwise tandem process, beginning with the aerobic oxidation of a thiol to afford a disulfide that is utilized in the oxidative sulfenylation of the imidazo[1,2-a]pyridine. This process has afforded diverse 3-sulfenylimidazo[1,2-a]pyridines of biological interest, and is environmentally friendly as benign H2O is the only by-product.