Near-infrared light-driven high-performance photocatalytic cross-coupling of non-active alkyl halides and thiols

Abstract Highly-efficient artificial synthesis of C−S bond-containing compounds has garnered widespread attention due to the crucial role of thioethers in constructing biomolecules, pharmaceuticals, and organic materials. Despite the photocatalytic synthesis of C(sp2)−S bonds from aryl halides using UV-visible light has been well-documented, achieving this with low-energy near-infrared (NIR) light remains challenging as the absence of a suitable NIR-activated photocatalytic system. Additionally, the application of readily available, while inactivated alkyl halides for C(sp3)−S bond construction has not yet been realized. Herein, we employed a designed composite photocatalyst (P2-Au), combining metal chalcogenide semiconductor clusters (P2) and gold nanorods (AuNRs), to achieve highly selective photocatalytic cross-coupling of alkyl halides and thiols under NIR irradiation. This protocol works well with diverse inert alkyl bromides/chlorides, and shows excellent functional group compatibility. Mechanistic studies revealed that hot electrons generated from AuNRs are transferred through P2 to activate halides, leading to the formation of alkyl radicals. Simultaneously, photo-induced holes on AuNRs oxidize thiols to thiol radicals, facilitating a radical-radical cross-coupling process for C–S bond formation. This work not only pushes the boundaries of energy utilization but also expands the substrate applicability toward photocatalytic C−S coupling in valuable organosulfur chemistry.