Aryloxybenzylidene Ruthenium Chelates: Synthesis, Structure and Catalytic Activity in Olefin Metathesis

New aryloxybenzylidene ruthenium chelates behave like a promising latent catalyst of olefin metathesis. The catalysts are characterised by substantial stability and catalytic inactivity in their dormant forms and a dramatic increase in activity after addition of a solution of HCl in ether. The mechanism of activation involves protonation of the phenoxide and the formation of a highly catalytically active hydroxybenzylidene ruthenium chelate.