Insertion of sulfur dioxide via a radical process: an efficient route to sulfonyl compounds

This review is focused on the recent advances in the chemistry of sulfur dioxide fixation through a radical process. Diverse sulfonyl compounds can be obtained efficiently under mild conditions. In general, aryl radicals, vinyl radicals, alkyl radicals, and nitrogen-centered radicals can react with sulfur dioxide, giving rise to sulfonyl radical intermediates. The resulting sulfonyl radicals can be captured by nucleophiles, olefins, and alkynes. The sources of aryl radicals from aryldiazonium salts, aryl halides, and diaryliodonium salts are demonstrated. It is believed that more amazing SO2-based achievements will be developed in the near future.