Photocatalytic Aerobic Oxidation of Thiols to Thiosulfonates

The photocatalytic aerobic oxidation of thiols to thiosulfonates remains a challenging transformation. In this study, we report a visible‐light‐mediated aerobic oxidation of thiols to thiosulfonates using molecular oxygen as a green oxidant. This eosin Y‐catalyzed protocol enables the efficient conversion of aryl and alkyl thiols to the corresponding thiosulfonates under mild conditions. Mechanistic studies support a dual reactive oxygen species (ROS) pathway involving singlet oxygen and superoxide anion radical. This cooperative oxidation system avoids stoichiometric chemical oxidants and provides an operationally simple and environmentally benign approach to valuable thiosulfonates.