Green and efficient synthesis of bidentate Schiff base Ru catalysts for olefin metathesis

A simple, green synthetic protocol to bidentate Schiff base substituted ruthenium carbene complexes is described. These complexes are potent catalysts for olefin metathesis, but the original synthetic route employs the Schiff base ligands in the form of highly toxic thallium(I) salts. The new protocol involves a two-step, quasi-one-pot approach and silver(I) carbonate as base. The target ruthenium carbene complexes are obtained in yields that are similar to, or better than, those of the original protocol.