Semiconductor Cluster with High Reduction Potential and Efficient Charge Transfer Enables Visible-Light-Driven Activation of Inert Organic Substrates.

Photoredox catalysis is an essential component of modern organic synthesis. However, current photocatalysts face the challenge of simultaneously requiring strong redox potentials and efficient charge transfer to meet the thermodynamic and kinetic demands of photoinduced electron transfer processes. Herein, we present an excellent reactivity mode for photocatalysis based on semiconductor clusters, exploiting the ideal Marcus parabola to couple potential and kinetic requirements. Our system demonstrates an exceptionally high negative reduction potential (E) (-2.94 V versus SCE, on par with K) and realizes efficient charge transfer-rapid charge separation (CS) and slow charge recombination (CR) kinetics. This duality endows the protocol with remarkable versatility by enabling the dearomatization of nonactivated arenes and reductive dehalogenation of challenging aryl/alkyl chlorides and aryl fluorides, as well as arylation and amination, with a high functional group tolerance under visible-light irradiation. Furthermore, this platform offers easy recyclability, supports gram-scale synthesis, and can be extended to the late-stage functionalization and deuteration of drugs. This innovative catalytic platform provides a new approach for the photochemical activation of inert organic substrates and is foreseen to promote the development of radical reaction-based pharmaceutical synthesis.