Water-mediated radical C-H tosylation of alkenes with tosyl cyanide

The water-mediated tosylation of alkenes with tosyl cyanide was discovered. Experimental investigations revealed that the reaction was initiated by the in situ formation of sulfinyl sulfone in the presence of water. The sulfinyl sulfone species decomposed to a sulfonyl radical and a sulfinyl radical through homolytic fission. The vinyl sulfone was afforded via sequential addition of the alkene to the sulfonyl radical and the sulfinyl radical, followed by -elimination of a sulfinyl moiety. A sulfinyl sulfone intermediate, generated in situ by the nucleophilic addition of water to tosyl cyanide, dominated the subsequent tosylation of alkenes via cascade di-radical addition/-elimination.