Synthesis of vinyl sulfides and thioethers via a hydrothiolation reaction of 4-hydroxydithiocoumarins and arylacetylenes/styrenes

The synthesis of vinyl sulfides (3a-m) and thioethers (7a-k), exclusive Markovnikov products, is reported by a copper(i) iodide catalyzed regioselective hydrothiolation reaction of terminal alkynes/alkenes and 4-hydroxydithiocoumarins. However, anti-Markovnikov hydrothiolation products (5a-f) were obtained in the case of 2-ethynylpyridine, with exclusive Z selectivity in good yields. The important aspects of this protocol are the absence of expensive metal complexes and additives to act as ligands, mild reaction conditions, high regioselectivity, good yields, and shorter reaction times.