Loss and Reformation of Ruthenium Alkylidene: Connecting Olefin Metathesis, Catalyst Deactivation, Regeneration, and Isomerization
نویسندگان
چکیده
منابع مشابه
Bis-mixed-carbene ruthenium-thiolate-alkylidene complexes: synthesis and olefin metathesis activity.
A series of bis-carbene Ru-hydride species, including (IMes)(Im(OMe)2)(PPh3)RuHCl (1) and (SIMes)(Me2Im(OMe)2)(PPh3)RuHCl (2) were prepared and subsequently shown to react with aryl-vinyl-sulfides to give the bis-carbene-alkylidene complexes: Im(OMe)2(SIMes)RuCl(SR)(=CHCH3) (R = p-FC6H4 (3), p-(NO2)C6H4 (4)), Im(OMe)2(IMes)RuCl(=CHCH3)(SPh) (5), Me2Im(OMe)2(SIMes)RuCl(=CHCH3)(SPh) (6), Im(OMe)2...
متن کاملPrevention of undesirable isomerization during olefin metathesis.
1,4-Benzoquinones have been found to prevent olefin isomerization of a number of allylic ethers and long-chain aliphatic alkenes during ruthenium-catalyzed olefin metathesis reactions. Electron-deficient benzoquinones are the most effective additives for the prevention of olefin migration. This mild, inexpensive, and effective method to block olefin isomerization increases the synthetic utility...
متن کاملThe isomerization equilibrium between cis and trans chloride ruthenium olefin metathesis catalysts from quantum mechanics calculations.
The cis-trans chloride isomerization of a ruthenium olefin metathesis catalyst is studied using quantum mechanics (B3LYP DFT), including the Poisson-Boltzmann (PBF) continuum approximation. The predicted geometries agree with experiment. The energies in methylene chloride, lead to DeltaG = -0.70 kcal/mol and a cis:trans ratio of 76:24, quite close to the experimental value of DeltaG = -0.78 kca...
متن کاملDeactivation of ruthenium olefin metathesis catalysts through intramolecular carbene-arene bond formation.
for olefin metathesis have been reported, for which strikingly different influences of the ligands on the efficiency of C C bond formation have been observed. For example, notable effects have been found in the class of alkoxy benzylidene ligands first introduced by Hoveyda and coworkers. Phosphine-free complexes such as the secondgeneration Hoveyda–Grubbs catalyst (4 ; IMesH2= 1,3-dimesityl-4,...
متن کاملEnantioselective Olefin Metathesis with Cyclometalated Ruthenium Complexes
The success of enantioselective olefin metathesis relies on the design of enantioenriched alkylidene complexes capable of transferring stereochemical information from the catalyst structure to the reactants. Cyclometalation of the NHC ligand has proven to be a successful strategy to incorporate stereogenic atoms into the catalyst structure. Enantioenriched complexes incorporating this design el...
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ژورنال
عنوان ژورنال: Journal of the American Chemical Society
سال: 2017
ISSN: 0002-7863,1520-5126
DOI: 10.1021/jacs.7b07694