Dinuclear Pathways for the Activation of Strained Three-Membered Rings

Dinuclear, strain-induced ring-opening reactions of vinylaziridines and vinylcyclopropanes are described. The previously reported [NDI]­Ni2(C6H6) complex (NDI = naphthyridine–diimine) reacts with N-tosyl-2-vinylaziridine via C–N oxidative addition to generate a dinickel metallacyclic product. On the basis of this stoichiometric reactivity, the [NDI]­Ni2(C6H6) complex is shown to be a highly active catalyst for the rearrangement of vinylcyclopropane to cyclopentene. Notably, 2-phenyl-1-vinylcyclopropane undergoes regioselective activation at the less hindered C–C bond in contrast to the noncatalytic thermal rearrangement. DFT calculations provide insight into the ability of the Ni–Ni bond to stabilize key intermediates and transition states along the catalytic pathway.