In situ generation of highly active olefin metathesis initiators

A ruthenium based benzylidene complex bearing an O,N-bidentate Schiff base ligand exhibits poor olefin metathesis activity but generates a highly active catalyst system when treated with acidic cocatalysts. Various Lewis acids were able to boost the ring opening metathesis polymerization (ROMP) of cycloocta-1,5-diene (COD). The best results were obtained with trichlorosilane (HSiCl3), which was also found to improve metathesis activity of the Grubbs second generation catalyst [RuCl2(double bond; length as m-dashCHPh)(H2IMes)(PCy3)] in the ROMP of COD and the ring closing metathesis (RCM) of diethyl diallylmalonate.