Ligand‐Controlled Cross‐Dimerization and ‐Trimerization of Alkynes under Nickel Catalysis

The cross‐dimerization of diphenylacetylene with trimethylsilylacetylene via CH bond cleavage in the presence of a catalytic amount of bis(cyclooctadiene)nickel [Ni(cod)2] together with a pyridine‐based ligand efficiently proceeds to give the corresponding enyne compound with good yield. In contrast, their 1:2 cross‐trimerization leading to a dienyne derivative takes place selectively using a triarylphosphine ligand. The regioselective cross‐dimerization of some unsymmetrical internal arylalkynes with terminal silylacetylenes is also accomplished using the pyridine ligand.