Theoretical investigation on the GaCl3-catalyzed ring-closing metathesis reaction of N-2,3-butadienyl-2-propynyl-1-amine: three-membered ring versus four-membered ring mechanism.

The gallium chloride (GaCl(3))-catalyzed ring-closing metathesis reaction mechanism of N-2,3-butadienyl-2-propynyl-1-amine has been studied at the Becke three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional (B3LYP)/6-31G(d), B3LYP/6-31+G(d,p), B3LYP/6-311++G(d,p)//B3LYP/ 6-31G(d) and the second-order Møller-Plesset perturbation (MP2)/6-311++G(d,p)//B3LYP/6-31+G(d,p) levels. It was found that the final metathesis product can be yielded via a three-membered or four-membered ring mechanism. The three-membered ring pathway is favorable due to its low energy barrier at the rate determining step. The whole reaction is stepwise and strongly exothermic.