Purple-Light Promoted Thiol-ene Reaction of Alkenes

Here we present a catalyst-free protocol for the purple light-mediated anti-Markovnikov functionalization of alkenes with thiols. Crucial to the generation of the thiyl radical was the formation of a key photo-active complex. More than 30 thioether products were obtained, demonstrating tolerance towards different functional groups and scalability up to 5 mmol of alkene. Two different reaction conditions have been developed, varying both the solvent and the amount of thiol. Depending on the alkene structure, water can be used as an alternative to dichloromethane as a solvent, thus increasing the sustainability of the whole process.