A simple sulfonylation strategy involving I2 and thiosulfonates, as sulfonyl-group precursors, is reported for the synthesis of vinyl sulfones. Sulfonyl radicals are presumed to be generated from thiosulfonates, which subsequently react with styrene or cinnamic acid derivatives to afford a variety of vinyl sulfones under the described reaction conditions. Detailed conditions, the substrate scope, and mechanistic studies are discussed.
We demonstrated that I2 promoted the formation of sulfonyl radicals from thiosulfonates, which are then delivered to styrene derivatives to afford synthetically useful vinyl sulfones in modest to good yields. Sulfonylation also successfully takes place with carboxylated olefins (cinnamic acid derivatives) with concomitant decarboxylation. Depending on the thiosulfonate substituent, interesting electronic effects are observed in these reactions. Thiosulfo-nates and cinnamic acid derivatives bearing electron-withdrawing groups afford products in higher yields, while styrene derivatives bearing electron-donating substituents are converted to vinyl sulfones in higher yields. The proposed reaction mechanisms are supported by control experiments using TEMPO and PhSO2I. Acknowledgments. This study was supported by the Human Resources Development of the KETEP grant (No. 20154010200820) from the Korea Government and the Ajou University Research Fund (S2017G000100012) Supporting Information. Additional supporting information is available in the online version of this article.
