In Situ Sulfur Modification Enables Electrochemical Selective Deuterated Thiol–Yne Reactions

The deuterated thiol-yne reaction using D₂O represents an attractive strategy for simultaneously introducing pharmaceutically relevant C(sp²)─D bonds and vinyl sulfide motifs. However, achieving high deuterium (D) incorporation remains a significant challenge. Herein, we report an electrochemical deuterated thiol-yne reaction that delivers D-containing vinyl sulfides with up to 98% alkene selectivity and 99% D incorporation, employing disulfides (RSSR) and D₂O over an in situ sulfur-modified nickel foam (NF) electrode. Mechanistic studies reveal a reductive cleavage of RSSR to RS⁻ intermediates, which subsequently form surface nickel sulfide (NiS_x) species through R─S bond cleavage. In situ and ex situ characterizations confirm the NiS_x formation and its role in reducing alkene adsorption, thereby suppressing its overreduction. This strategy demonstrates broad applicability across terminal and internal alkynes, as well as aromatic and aliphatic disulfides, furnishing 30 diverse examples of D-labeled vinyl sulfides.