Sulfinates from Amines: A Radical Approach to Alkyl Sulfonyl Derivatives via Donor-Acceptor Activation of Pyridinium Salts

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.

Automated summary

A catalyst-free procedure is used to generate primary, secondary, and benzylic alkyl radicals from readily available amines, which are then trapped by SO2 to form sulfonyl radicals. These sulfonyl radicals are then converted into alkyl sulfinate products through hydrogen atom transfer from Hantzsch ester, allowing for the preparation of medicinal chemistry relevant sulfonyl-containing motifs.