Thiosulfonylation of Unactivated Alkenes with Visible-Light Organic Photocatalysis

A metal-free method for the vicinal thiosulfonylation of unactivated alkenes with thiosulfonates using 9-mesityl-10-methylacridinium perchlorate as the photo-organocatalyst with visible-light irradiation has been developed. The method can be performed in dimethyl carbonate under air at room temperature and features a broad functional group compatibility. Metrics indicate the green potential of the developed versus the state-of-the-art methodologies. Mechanistic studies revealed no single electron transfer but involvement of an energy transfer from the excited photo-organocatalyst to thiosulfonate reactant, subsequently providing a sulfenyl and a sulfonyl radical via homolytic cleavage.