Hydrothiolation of Alkenes and Alkynes Catalyzed by 3,4-Dimethyl-5-vinylthiazolium iodide and Poly(3,4-dimethyl-5-vinylthiazolium) iodide

The highly selective anti-Markovnikov addition of thiols to unactivated alkenes and alkynes was demonstrated by using 3,4-dimethyl-5-vinylthiazolium iodide or its polymer, poly(3,4-dimethyl-5-vinylthiazolium) iodide, as a complementary catalyst. The reaction proceeded cleanly under base-free conditions in air with both aromatic and aliphatic thiols. The polymer catalyst showed a high turnover number (approximate to 5800) and could be reused up to four times without any loss of catalytic activity. DFT calculations supported stabilization of the thiyl radical intermediate by the thiazolium cation, which resulted in reaction of the radical with unsaturated C-C bonds.