Comparative investigation of kinetic consequences associated with long-range electronic effects on catalytic ruthenium-promoted ring-closing metathesis

When exposed to the Grubbs ruthenium catalyst, trienyl substrates of type 4 undergo highly regioselective ring closure to give the common product 5. These reactions proceed invariably under pseudo-first-order kinetics, considerably faster when X=H (t1/2=9.1), followed by X=CO2Et (t1/2=26.5).