Iron-Catalyzed Selective Sulfonylation of Alkenes by Sulfonyl Chlorides.

Herein, we report an iron-catalyzed approach for the generation of sulfonyl radicals from readily available bulk raw material sulfonyl chlorides and selective sulfonylation of alkenes for the synthesis of β-keto sulfones and vinyl sulfones depending on the reaction conditions. Under mild aerobic oxidation conditions in ethanol, β-keto sulfones were obtained via C(sp2)-C bond cleavage, while under argon protection in hexafluoroisopropanol, vinyl sulfones were formed. Mechanism studies reveal that iron salts play the role of hitting two birds with one stone, involving hydrogen atom transfer (HAT) and single-electron transfer (SET) processes.