Palladium-Catalyzed Carbothiolation of Alkenes and Alkynes for the Synthesis of Heterocycles

The intramolecular carbothiolation of unsaturated hydrocarbons using a palladium–NHC catalyst (NHC = N-heterocyclic carbene) is described. Herein, a single catalyst system enables both initial activation of a C­(sp2)–S bond through oxidative addition and formation of a C­(sp3)–S bond through a terminal reductive elimination, unlocking a completely atom-economical transfer across alkenes. The reaction tolerates a variety of different functional groups, exhibits excellent chemoselectivity in the presence of competing thioether moieties, and can be applied to various alkenes and alkynes. Furthermore, product derivatization was demonstrated to access a broad variety of sulfur-containing compounds.