"Ligand-Free" CuI-Catalyzed Highly Efficient Intramolecular S-Vinylation of Thiols with Vinyl Chlorides and Bromides

With CuI as the catalyst and K3PO4·3H2O as the base, highly efficient intramolecular S-vinylation of thiols with vinyl chlorides or bromides was successfully implemented without the help of an additional ligand. Moreover, the competition experiments revealed that the 4-exo cyclization is fundamentally preferred over other modes (5-exo, 6-exo, and 6-endo) of cyclization.