Regio‐ and stereoselective addition of a silyl‐substituted alkynyl sulfide to various terminal alkynes proceeds in the presence of a palladium catalyst to give (Z)‐1‐thio‐1,3‐enynes, which are useful building blocks for the synthesis of polysubstituted 1,3‐enynes. Addition to internal alkynes also takes place under solvent‐free conditions (see scheme).
slightly modified conditions. The C-S bond-forming reaction is reversible: A reaction of a thiol and a 1-alkylthio-1-alkyne in the presence of the rhodium catalyst gave a 1-alkyne; alkylthio exchange reaction proceeded between a 1-alkylthio-1-alkyne and a disulfide. This is an equilibrating oxidative reaction of organic molecules with C-H and S-S bond metathesis forming C-S and S-H bonds.