Visible-Light-Promoted C–S Cross-Coupling via Intermolecular Charge Transfer

Disclosed is a mild, scalable, visible-light-promoted cross-coupling reaction between thiols and aryl halides for the construction of C–S bonds in the absence of both transition metal and photoredox catalysts. The scope of aryl halides and thiol partners includes over 60 examples and therefore provides an entry point into various aryl thioether building blocks of pharmaceutical interest. Furthermore, to demonstrate its utility, this C–S coupling protocol was applied in drug synthesis and late-stage modifications of active pharmaceutical ingredients. UV–vis spectroscopy and time-dependent density functional theory calculations suggest that visible-light-promoted intermolecular charge transfer within the thiolate–aryl halide electron donor–acceptor complex permits the reactivity in the absence of catalyst.