Alkyne as a spectator ligand for the nickel-catalyzed multicomponent connection reaction of diphenylzinc, 1,3-butadiene, aldehydes, and amines.

Under nickel catalysis, in the presence of 3-hexyne, the aldimines of aromatic amines react with Ph2Zn and one molecule of butadiene to provide 1 exclusively, while the aldimines of aliphatic amines react with Ph2Zn and two molecules of butadiene to provide 2 exclusively, where 3-hexyne serves as a spectator ligand controlling the selective formation of 1 and 2.