An Efficient Copper-Catalyzed Homocoupling of Terminal Alkynes to Give Symmetrical 1,4-Disubstituted 1,3-Diynes

A facile and efficient pathway for the copper iodide and ligand N,N,N',N'-tetramethylethane-1,2-diamine promoted homocoupling reaction of terminal alkynes under ambient temperature and air as an oxidant was reported. The alkynes, including aromatic alkynes and aliphatic alkynes, could afford the symmetrical 1,4-disubstituted 1,3-diynes in good to excellent yields.