The reaction of (E)-2-aryl-1-chlorovinyl p-tolyl sulfoxides with lithiumacetylides gave a variety of (Z)-3-arylhex-3-ene-1,5-diynes in yields of up to 80% with high stereoselectivity. The structure of the (Z)-enediyne was confirmed by X-ray molecular structure analysis. The result of the reaction with deuterium- and 13C-labeled sulfoxide suggested that the reaction proceeds through cleavage of the