Visible-light–induced regioselective chalcogenation of indoloquinoxalines via cross-dehydrogenative coupling under metal-free, open-air conditions

Abstract

A simple yet efficient method involving a visible-light–induced direct, regioselective chalcogenation of indoloquinoxaline derivatives has been developed. Thiols, disulfides and diselenides were found to be efficient as chalcogenating agents in the presence of Rose Bengal as a photosensitizer. This photoinduced C–H functionalization via a cross-dehydrogenative-coupling (CDC) protocol was carried out at ambient temperature under an open-air atmosphere. A library of chalcogenated indoloquinoxaline derivatives was prepared, and selected compounds were investigated for their photophysical properties. Excellent yield, procedural ease, broad functional group tolerance and exclusive regioselectivity were found to be the noticeable features of this photochemical method, with hassle-free scalability and consistent reproducibility further enhancing its appeal for industrial application.