Radical sulfonylation with sulfur dioxide surrogates

Sulfur dioxide is a toxic atmospheric pollutant, primarily emitted from the combustion of sulfur-containing fossil fuels. The development of clean and cost-effective chemical processes for capturing SO₂ has garnered significant interest from both industry and academia. On the other hand, sulfonyl-derived functional groups occupy a significant position in pharmaceuticals, agrochemicals and materials science. As versatile building blocks, sulfonyl groups can be utilized in a variety of bond-forming reactions in modern organic chemistry. Thus, the direct synthesis of these SO₂-containing compounds from SO₂ under mild conditions represents a more atom-efficient and greener approach. Owing to the troublesome issue of using toxic and malodorous gaseous SO₂, sulfonylation reactions involving diverse SO₂ surrogates provide an efficient and promising method for the synthesis of SO₂-containing compounds. Since 2014, radical-mediated SO₂ insertion strategies have attracted significant attention. By using photocatalysis, electrochemistry, transition-metal catalysis, and thermal initiation, significant progress has been made toward radical sulfonylation with SO₂ surrogates. This review highlights the advances from the past decade that provide readers with essential tools for designing and implementing radical sulfonylation using SO₂ surrogates in organic synthesis.