Direct C-H sulfenylation of quinoxalinones with thiols under visible-light-induced photocatalyst-free conditions

A photocatalyst-free visible-light-promoted sulfenylation of quinoxalinones with thiols via cross-dehydrogenative coupling was developed. This protocol allowed the direct formation of diverse 3-sulfenylquinoxalin-2(1H)-ones under metal- and catalyst-free conditions and using air (O-2) as an oxidant. Furthermore, a range of readily accessible thiols and quinoxalin-2(1H)-ones was applied in this coupling, resulting in an attractive process of accessing 3-substituted quinoxalinones.