Radical Alkynylthiolation with Visible-Light-Sensitive <i>S</i>-Alkynylthio Sulfonates

A novel kind of <i>S</i>-alkynylthio sulfonate, which can be directly activated under visible-light irradiation, has been developed for the radical addition of multiple bond systems and radical coupling with diazonium salts under photocatalyst-free conditions. This strategy features a broad substrate scope, high regioselectivity, excellent tolerance of functional groups, and the late-stage modification of drugs. Experimental and theoretical mechanistic investigations gave reasonable insight into the photolysis of <i>S</i>-alkynylthio sulfonates and C-S bond formation.