Copper-Catalyzed Diazo Cross-/Homo-Coupling toward Tetrasubstituted Olefins and Applications on the Synthesis of Maleimide Derivatives.

A challenging selective intermolecular cross-coupling and homocoupling of aryl-aryl or aryl-alkyl diazo compounds has been accomplished via a copper system, which afforded tetrasubstituted olefins in moderate to high yields with good to excellent Z-selectivity. This novel methodology enables rapid synthesis of tetrasubstituted olefins, which would find broad application in accessing maleimide libraries of nature products and bioactive small molecules.