Enones 1 reacted with two molecules of alkynes 2 (R= R'in eq 1) in the presence of a nickel (0) and aluminum catalytic system to give cyclotrimerization adducts regioselectively. Aluminum phenoxide (Me n Al (OPh) 3-n (n= 0-3)) functions as a Lewis acid cocatalyst and activates 1. Stoichiometric experiments suggest that the cycloaddition of 1 and 2 proceeds via nickelacyclopentadiene intermediates, which are formed by the oxidative coupling of ...
