Clean, Convenient, High‐yield Access to Second‐generation Ru Metathesis Catalysts from Commercially Available Precursors

Abstract Expedient routes are described to the three dominant ruthenium catalysts currently used for olefin metathesis: the second‐generation Grubbs, Hoveyda, and indenylidene catalysts. Ligand exchange of the first‐generation PCy 3 complexes with isolated free H 2 IMes, followed by treatment with a cation‐ exchange resin to remove the liberated phosphine, affords the clean targets in ≥95 % isolated yield from commercially available precursors, with no workup other than filtration and evaporation.