Sulfonium Salt-Mediated Bisthiolation of Terminal Alkynes to Access Symmetrical and Nonsymmetrical <i>Z-</i> 1,2 <i>-</i> Dithioalkenes

In this study, we report an efficient one-pot bisthiolation reaction of terminal alkynes, which enables the regio- and stereoselective synthesis of diverse symmetrical and nonsymmetrical (<i>Z</i>)-1,2-dithioalkenes with wide substrate scope and excellent functional group compatibility. Mechanistic investigations reveal that the reaction is initiated by in situ-generated alkynyl sulfonium salts, formed from terminal alkynes, sulfoxides, and triflic anhydride (Tf₂O). Gram-scale synthesis and late-stage functionalization further underscore the application of this method in organic synthesis.