Construction of β-Hydroxysulfones via a Photoinduced Four-Component Reaction

A photoinduced radical difunctionalization of alkenes with Na₂S₂O₅, aryl thianthrenium salts, and H₂O to construct β-hydroxysulfones is reported. The reaction proceeds under mild conditions with a broad substrate scope and excellent functional group compatibility, including late-stage modification of drug-like molecules. EPR studies support a radical pathway involving visible-light-induced generation of the aryl radical from thianthrenium salt followed by sulfur dioxide insertion to form the sulfonyl radical intermediate.