Copper-Catalyzed Double Thiolation To Access Sulfur-Bridged Imidazopyridines with Isothiocyanate

A copper­(I)-catalyzed sulfur-bridged dimerization of imidazopyridines has been developed using isothiocyanate as the sulfur source. This method enables a switchable synthesis of bis­(imidazo­[1,2-a]­pyridin-3-yl)­sulfanes or bis­(2-(imidazo­[1,2-a]­pyridin-2-yl)­phenyl)­sulfanes in the presence of 4-dimethylaminopyridine (DMAP) or K2CO3 when different imidazopyridines were employed. Under optimized conditions, a variety of sulfur-bridged imidazopyridines were obtained in good yields. Moreover, thiourea was proved to be the key intermediate under catalytic system A.