Ruthenium-based metathesis catalysts, precursors for their preparation and their use

A method for preparing

• a ruthenium catalyst of formula (II)
• comprising reacting a compound of formula (I)
• wherein
• a, b, c and d are, independently from each other, selected from hydrogen, straight chain or branched alkyl groups including C1-C10-alkyl, C1-C10-alkoxy, C1-C10-alkylthio, C1-C10-silyloxy, C1-C10-alkylamino, optionally substituted C6-C14-aryl, optionally substituted C6-C14-aryloxy, optionally substituted C6-C14-heteroaryl or electron-withdrawing groups (EWG);
• R1 is hydrogen, straight chain or branched C1-C10-alkyl, C1-C10-alkoxy, C1-C10-alkylthio, C1-C10-silyloxy, C1-C10-alkylamino, C1-C10-dialkylamino, C6-C14-aryl, C6-C14-aryloxy, C6-C14-heterocyclic or electron-withdrawing groups (EWG);
• R2 is hydrogen, straight chain or branched C1-C10-alkyl groups with a Ru-starting compound having the formula (V):
• in a cross metathesis reaction,
• wherein
• L is a phosphine ligand selected from the group of tri-iso-propyl-phosphine, tricyclohexylphosphine (PCy3), tricyclopentylphosphine, cyclohexylphobane, 2,2,4-trimethylpentylphobane or isobutyl-phobane or a NHC ligand selected from the group of 1,3-bis-(2,4,6-trimethylphenyl)-imidazolidine-2-ylidene (“SIMes”), 1,3-bis-(2,6-di-isopropylphenyl)-imidazolidine-2-ylidene (“SIPr”) or 1,3-bis-(2,6-di-isopropylphenyl)-imidazoline-2-ylidene (“IPr”) and
• L′ is substituted or unsubstituted pyridine ligand;
• X is an anionic ligand selected from the group of halogen anions (Cl−, Br−, I−).