Metal-free Radical Reductive C-C Coupling of Thiols and Alkenes

An intermolecular reductive C-C coupling of electrophilic alkyl radicals and alkenes has been developed. Thiols was used as both hydrogen-donating reagent and alkyl radical precursors in the presence of triethyl phosphite and radical initiator. A wide range of alkenes, including styrenes, aliphatic olefins were tolerated well in this transformation. Mechanistic studies indicate that a phosphite promoted radical desulfidation of thiols to access electrophilic alkyl radicals and the radical chain propagation process may be involved in this transformation.