Regioselective [2 + 2 + 2] Cycloaddition of a Nickel−Benzyne Complex with 1,3-Diynes

[reaction: see text] Reactions of nickel(0)-benzyne complexes with a range of symmetrically substituted 1,3-diynes in the presence of triethylphosphine lead to the regioselective formation of 2,3-dialkynyl naphthalenes. The regioselectivity can be reversed when the diyne possesses substituents of high steric bulk, allowing selective formation of either symmetric dialkynyl naphthalene.