Chemo- and Regioselective Addition of Carboxylic Acid to the Alkylthio-­Activated Enyne Triple Bond in the Absence of Catalysts

A series of methyl 3-acetoxy-2-(1,3-dithiolane-2-ylidene)but-3-enoate derivatives has been synthesized by the chemo- and regioselective addition of carboxylic acids to the alkyl­thio-activated terminal alkynes in moderate to high yields in the ­absence of catalysts.