【Energy and Environmental Chemistry】Light-Driven Sulfur Enables a New Reaction Platform: Sulfur Species Act Catalytically to Activate Inert Substrates

A research team led by Prof. Hirohisa Ohmiya, Assistant Prof. Sho Murakami, and graduate student Ryo Yanagida has developed a new reaction platform that enables the generation of carbon radicals under visible light without the use of external photocatalysts or metal reagents. The study was carried out in collaboration with Valero Gimeno Alfonso (Institute of Chemical Research of Catalonia) and Justin Ching (University of Toronto).
Carbon radicals are key intermediates in the synthesis of pharmaceuticals and functional materials. However, generating these species from readily available starting materials remains challenging, as many common substrates are resistant to single-electron activation and typically require costly photocatalysts or metal-based reagents. In this study, the researchers demonstrated that sulfur-containing intermediates, formed in situ through polar activation, can act as photoactive species under visible light irradiation. Upon light absorption, these sulfur-derived species promote homolytic cleavage of carbon–sulfur bonds, enabling the efficient generation of carbon radicals without the need for external photocatalysts.
Importantly, this method is applicable to redox-inert substrates such as unactivated alkyl chlorides and epoxides, which are traditionally difficult to activate under mild conditions. The generated carbon radicals can be directly utilized in carbon–carbon bond-forming reactions, providing a simple and practical approach to molecular construction. Mechanistic studies suggest that sulfur-based anionic species generated during the reaction accumulate and contribute to sustained radical formation under light irradiation, enhancing overall reaction efficiency. These findings demonstrate that sulfur-based intermediates can function not only as structural elements but also as photoactive components that drive chemical transformations. This approach is expected to contribute to the development of more practical and sustainable synthetic methods in organic chemistry.

The results were published online on April 14, 2026, in the Journal of the American Chemical Society.

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Organic Reaction Chemistry