Nickel(II) Chloride-Catalyzed Regioselective Hydrothiolation of Alkynes



Regioselective Markovnikov-type addition of PhSH to alkynes (HC≡C-R) has been performed using easily available nickel complexes. The non-catalytic side reaction leading to anti-Markovnikov products was suppressed by addition of γ-terpinene to the catalytic system. The other side reaction leading to the bis(phenylthio)alkene was avoided by excluding phosphine and phosphite ligands from the catalytic system. It was found that catalytic amounts of Et3N significantly increased the yield and selectivity of the catalytic reaction. Under optimized conditions high product yields of 60–85% were obtained for various alkynes [R=n-C5H11, CH2NMe2, CH2OMe, CH2SPh, C6H11(OH), (CH2)3CN]. The X-ray structure of one of the synthesized products is reported.