Mechanism of Intermolecular Ene-yne Metathesis Promoted by the Grubbs First-Generation Catalyst: An Alternative Entry Point to Catalysis

The kinetics of intermolecular alkene-alkyne (ene-yne) metathesis promoted by the first generation Grubbs catalyst (Cy(3)P)(2)Cl(2)Ru=CHPh (1) were investigated. The dissociated tricycloherylphosphine plays an important kinetic role during the initial exchange with the terminal alkyne, resulting in a half-order rate dependence on 1 and first-order dependence on the alkyne.