Radical Sulfonylation of Diazo Compounds With Sulfinates Triggered by Formation of Photoactive Electron Donor–Acceptor Complex

A visible‐light‐promoted radical sulfonylation reaction of trifluoromethyl alkyl diazo compounds with sodium sulfinates has been developed. This photo‐induced protocol of diazo compounds undergoes an unexpected nitrogen retention process leading to the formation of trifluoromethyl hydrazones as products in yields up to 78%. A series of spectrometric and mechanistic experiments, in combination with density functional theory calculations, discloses that this sulfonylation reaction is triggered by the formation of an electron donor–acceptor (EDA) complex between diazo compounds and sodium sulfinates, followed by fragmentation to generate diazo radical cations and sulfonyl radicals. This work reports a new example of EDA complexes between diazo compounds and sulfinates, and also represents a new reaction mode of diazo compounds.