Palladium-free synthesis of unsymmetrical diarylethynes by cross-coupling reaction of alkynylboronates with aryl iodides catalyzed by CuCl

A series of unsymmetrical diarylethynes have been synthesized by the copper-catalyzed cross-coupling reaction of alkynylboronates with aryl iodides in high to excellent yields under palladium-free conditions. A wide range of substrates bearing an electron-donating or an electron-withdrawing substituent on the aromatic ring are compatible with this reaction.