Flash Communication: <i>N</i>-Heterocyclic Carbene Nickel-Mediated C–C Activation of Substituted Vinylcyclobutanes

The C–C activation of three substituted vinylcyclobutanes by [(IPr)Ni(0)] (IPr = ((1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) complexes was evaluated. Both 1,2-dicyclobutylethylene and β-caryophyllene underwent oxidative ring-opening with [(IPr)Ni(0)] to furnish isolable 7-membered alkyl, allyl-metallacycles at ambient temperature. In contrast, a derivative of β-caryophyllene bearing terminal alkenes resulted in formation of an isolable nickel bis(olefin) complex that exhibited only partial conversion to the metallacycle upon heating to 80 °C.