Synthetically versatile alkyl sulfinates can be prepared from readily available amines, using Katritzky pyridinium salt intermediates. In a catalyst-free procedure, primary, secondary, and benzylic alkyl radicals are generated by photoinduced or thermally induced single-electron transfer (SET) from an electron donor–acceptor (EDA) complex, and trapped by SO2 to generate sulfonyl radicals. Hydrogen atom transfer (HAT) from Hantzsch ester gives alkyl sulfinate products, which are used to prepare a selection of medicinal chemistry relevant sulfonyl-containing motifs.

The introduction of easy-to-handle SO2 surrogates has transformed the field of sulfur chemistry, enabling methodologies utilizing SO2 to be carried out without specialized apparatus, and paving the way for the development of new procedures. This review highlights some of the varied and significant developments associated with one of the most prominent SO2 surrogates: DABSO.1 Introduction2 DABSO3 Reactions with Nucleophilic Reagents4 Metal-Catalyzed Reactions4.1 Palladium-Catalyzed Reactions4.2 Other Transition-Metal Catalysis5 Radical Reactions5.1 Aryldiazonium Salts5.2 Other Aryl Radical Precursors5.3 Alkyl Radical Precursors6 Conclusion

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