A mild, general, and efficient copper-catalyzed system for C–S bond formation with high chemoselectivity and wide functional group tolerance is developed. With CuBr as catalyst and 1, 2, 3, 4-tetrahydro-8-hydroxy-quinoline as ligand, the S-arylation of thiols with aryl halides performed well, the activated aryl iodides could take place even at room temperature, and the activated aryl bromides and chlorides give the corresponding ...