Hydrothiolation of alkynes with thiol-catechol derivatives catalysed by CuNPs/TiO 2 : exploring the reaction mechanism by DFT calculations.

Density functional theory (DFT) calculations were applied to describe the hydrothiolation reaction of activated alkynes with thiols bearing a catechol group. The thiol-yne click (TYC) process was efficiently catalysed by a CuNPs/TiO 2 nanocatalyst giving the corresponding anti -Markovnikov vinyl sulphides with high Z -stereoselectivity. Based on the experimental results and DFT studies, a plausible reaction mechanism is proposed, which implies the activation of the carbon-carbon triple bond by coordination to the copper centre, followed by a stereoselective (external) nucleophilic attack to give preferentially the Z -vinyl sulphide isomer. Additionally, experimental and theoretical studies strongly correlate with the proposed synergistic role for the TiO 2 support in the catalytic process.