CCl₄-TMEDA-CuCl-A Novel Convenient Catalytic System for Dimerization of Terminal Acetylenes in Mild Conditions

A novel catalytic system for homocoupling terminal acetylenes was elaborated based on CuCl as a catalyst (10 mol%), TMEDA as a base and CCl4 as an oxidant. The influence of the solvent, base, amount of catalyst and CCl4 on the reaction was investigated. Methanol was found to be the solvent of choice. The broad synthetic scope of the reaction was demonstrated. Diynes with various substituents were prepared in up to 92% yields. The possible reaction mechanism is discussed.