- Ruthenium-indenylidene complexes: Powerful tools for metathesis transformations
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Ruthenium-indenylidene complexes represent a class of robust and efficient pre-catalysts for olefin metathesis reactions. In this feature article, we provide an overview of the various complexes belonging to this family and summarise their use in various applications. The relation between the nature of ancillary ligands around the metal coordination sphere of these complexes and their catalytic activity is also discussed. The Royal Society of Chemistry.
- Boeda, Fabien,Clavier, Herve,Nolan, Steven P.
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- Synthesis of N-heterocylic carbene-containing metal complexes from 2-(pentafluorophenyl)imidazolidines
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N-Heterocyclic carbene (NHC)-containing metal complexes are prepared through a simple, base-free method involving the decomposition of 2-(pentafluorophenyl)imidazolidines under mild thermolytic conditions. Ruthenium, iridium, and rhodium complexes containing NHC ligands with different electronic and steric parameters are reported.
- Blum, Angela P.,Ritter, Tobias,Grubbs, Robert H.
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- Merrifield resin-assisted routes to second-generation catalysts for olefin metathesis
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Phosphine-scavenging resins can significantly facilitate the synthesis of highly active Ru metathesis catalysts, including the second-generation Grubbs, Hoveyda, and indenylidene catalysts (GII, HII, InII). These catalysts are customarily prepared by ligand exchange of the corresponding first-generation catalysts with the N-heterocyclic carbene (NHC) H2IMes. The PCy3 coproduct is conventionally removed by pentane extraction, but the partial solubility of the desired Ru products can cause product losses of over 20%. Sequestration of the PCy3 coproduct with CuCl is more efficient, but is undesirable given the potential for non-innocent copper residues. Use of the arylsulfonic acid resin Amberlyst-15 delivers near-quantitative catalyst yields, but the high acidity of the resin leads to problems with reproducibility and decomposition. An alternative approach is described, in which a neutral Merrifield resin (crosslinked polystyrene with pendant p-C6H4CH2I groups; MF-I) is used to sequester PCy3 as the covalently-tethered benzylphosphonium salt. Addition of MF-I following complete ligand exchange effects quantitative uptake of free PCy3 (and any residual free NHC) within 45 min at RT: the clean products are isolated by filtration, in ca. 95% yield. These yields compare well with those obtained via the Amberlyst-15 route, without the challenges due to resin acidity. The efficacy of this methodology is demonstrated in the synthesis of isotopically-labelled derivatives of HII, in which the H2IMes ligand bears a 13C-label at the carbene carbon, or perdeuterated mesityl rings.
- Nascimento, Daniel L.,Davy, Emma C.,Fogg, Deryn E.
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- A versatile precursor for the synthesis of new ruthenium olefin metathesis catalysts
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The ruthenium complex (IMesH2)(Cl)2(C5H5N)2Ru=C HPh [IMesH2 = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene] (3) was prepared by the reaction of (IMesH2)(PCy3)(Cl)2Ru=CHPh (2) with an excess of pyridine. Complex 3 contains substitutionally labile pyridine and chloride ligands and serves as a versatile starting material for the synthesis of new ruthenium benzylidenes.
- Sanford, Melanie S.,Love, Jennifer A.,Grubbs, Robert H.
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- N-Heterocyclic carbene-based ruthenium-hydride catalysts for the synthesis of unsymmetrically functionalized double-decker silsesquioxanes
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Ruthenium-N-heterocyclic carbene complexes with the generic formula [RuHCl(CO)(NHC)(PCy3)] exhibit a high catalytic activity toward the (E)-selective silylative coupling of divinyl-substituted double-decker silsesquioxanes with two distinctly substituted styrenes. This process leads to a novel class of unsymmetrically functionalized silsesquioxane derivatives.
- Zak, Patrycja,Delaude, Lionel,Dudziec, Beata,Marciniec, Bogdan
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- SYNTHESIS AND CHARACTERIZATION OF METATHESIS CATALYSTS
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This invention relates generally to olefin metathesis catalysts, to the preparation of such compounds, compositions comprising such compounds, methods of using such compounds, and the use of such compounds in the metathesis of olefins and in the synthesis of related olefin metathesis catalysts. The invention has utility in the fields of catalysis, organic synthesis, polymer chemistry, and in industrial applications such as oil and gas, fine chemicals, and pharmaceuticals.
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Paragraph 000150; 000151
(2018/03/25)
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- IMIDAZOLIDINE-BASED METAL CARBENE METATHESIS CATALYSTS
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The present invention relates to novel metathesis catalysts with an imidazolidine-based ligand and to methods for making and using the same. The inventive catalysts are of the formula wherein: M is ruthenium or osmium;X and X1 are each independently an anionic ligand;L is a neutral electron donor ligand; and,R, R1, R6, R7, R8, and R9 are each independently hydrogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthiol, aryl thiol, C1-C20 alkylsulfonyl and C2-C20 alkylsulfinyl, the substituent optionally substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, aryl, and a functional group selected from the group consisting of hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen. The inclusion of an imidazolidine ligand to the previously described ruthenium or osmium catalysts has been found to dramatically improve the properties of these complexes. The inventive catalysts maintains the functional group tolerance of previously described ruthenium complexes while having enhanced metathesis activity that compares favorably to prior art tungsten and molybdenum systems.
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Paragraph 0058
(2016/09/12)
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- Cross-metathesis reaction of functionalized and substituted olefins using group 8 transition metal carbene complexes as metathesis catalysts
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The invention pertains to the use of Group 8 transition metal carbene complexes as catalysts for olefin cross-metathesis reactions. In particular, ruthenium and osmium alkylidene complexes substituted with an N-heterocyclic carbene ligand are used to catalyze cross-metathesis reactions to provide a variety of substituted and functionalized olefins, including phosphonate-substituted olefins, directly halogenated olefins, 1,1,2-trisubstituted olefins, and quaternary allylic olefins. The invention further provides a method for creating functional diversity using the aforementioned complexes to catalyze cross-metathesis reactions of a first olefinic reactant, which may or may not be substituted with a functional group, with each of a plurality of different olefinic reactants, which may or may not be substituted with functional groups, to give a plurality of structurally distinct olefinic products. The methodology of the invention is also useful in facilitating the stereoselective synthesis of 1,2-disubstituted olefins in the cis configuration.
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Page/Page column 43
(2016/08/29)
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- Switched stereocontrol in Grubbs - Hoveyda complex catalyzed ROMP utilizing proton-switched NHC ligands
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Grubbs-Hoveyda and Grubbs III type complexes with ferrocenyl- or -NEt 2-substituted NHC ligands were synthesized according to standard procedures. The electron donation of the NHC ligands in the respective ruthenium complexes can be modulated by oxidation of the ferrocenyl moiety or by protonation of the amino group. The neutral and the respective cationic (oxidized or protonated) ruthenium complexes were tested in the ROMP of norbornene. The change in the electron donation of the NHC ligands upon protonation leads to a significant change in the double-bond geometry (from E/Z ratio = 0.78 to E/Z = 1.04) and in the microstructure of the resulting polynorbornene. Consequently, addition of acid and protonation of the living catalyst attached to the polymer chain during the polymerization reaction allows fine-tuning the E/Z ratio of the resulting polynorbornene.
- Peeck, Lars H.,Leuthaeusser, Steffen,Plenio, Herbert
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p. 4339 - 4345
(2011/01/03)
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- Olefin metathesis catalysts containing acyclic diaminocarbenes
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The first examples of ruthenium-based olefin metathesis catalysts containing acyclic diaminocarbene (ADC) ligands are reported. Complexes of the type (ADC)(SIMeS)Cl2Ru=CHPh and (ADC)Cl2Ru=CH(2- isopropoxy)Ph (ADC = N,N'-dimethylformamidin-2-ylidene or N,N'-bis(2,6-di- isopropylphenyl)-N,N'-dimethylformamidin-2-ylidene; SIMes = 1,3- dimesitylimidazolin-2-ylidene) were synthesized and studied in solution as well as in the solid state. Depending on their N-substituents and the metal center to which they were coordinated, the aforementioned ADC ligands were found to adopt different conformations. Preliminary investigations revealed that these Ru complexes exhibited high catalytic activities in a variety of olefin metathesis reactions at elevated temperatures and afforded cross-metathesis products with significantly lower E:Z ratios than catalysts containing analogous N-heterocyclic carbene ligands.
- Rosen, Evelyn L.,Sung, Daphne H.,Chen, Zheng,Lynch, Vincent M.,Bielawski, Christopher W.
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p. 250 - 256
(2010/04/04)
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- Kinetic and thermodynamic analysis of processes relevant to initiation of olefin metathesis by ruthenium phosphonium alkylidene catalysts
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Initiation processes in a family of ruthenium phosphonium alkylidene catalysts, some of which are commercially available, are presented. Seven 16-electron zwitterionic catalyst precursors of general formula (H 2lMes)(Cl)3Ru=C(H)P(Rs
- Leitao, Erin M.,Van Der Eide, Edwin F.,Romero, Patricio E.,Piers, Warren E.,McDonald, Robert
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p. 2784 - 2794
(2010/06/11)
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- π-face donor properties of N-heterocyclic carbenes
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The donor properties of aryl substituted N-heterocyclic carbenes are characterized by lone pair donation from the carbene carbon and, as is shown here, by donation of electron density of the aromatic π-face of the NHC aryl groups towards the metal. The Royal Society of Chemistry 2005.
- Suessner, Marcus,Plenio, Herbert
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p. 5417 - 5419
(2007/10/03)
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- Synthesis and activity of ruthenium alkylidene complexes coordinated with phosphine and N-heterocyclic carbene ligands
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This paper reports the synthesis and characterization of a variety of ruthenium complexes coordinated with phosphine and N-heterocyclic carbene (NHC) ligands. These complexes include several alkylidene derivatives of the general formula (NHC)(PR3)(Cl)2Ru=CHR′, which are highly active olefin metathesis catalysts. Although these catalysts can be prepared adequately by the reaction of bis(phosphine) ruthenium alkylidene precursors with free NHCs, we have developed an alternative route that employs NHC-alcohol or -chloroform adducts as "protected" forms of the NHC ligands. This route is advantageous because NHC adducts are easier to handle than their free carbene counterparts. We also demonstrate that sterically bulky bis(NHC) complexes can be made by reaction of the pyridine-coordinated precursor (NHC)(py)2(Cl)2Ru=CHPh with free NHCs or NHC adducts. Two crystal structures are presented, one of the mixed bis(NHC) derivative (H2IMes)(IMes)(Cl)2Ru=CHPh, and the other of (PCy3)(Cl)(CO)Ru[η2-(CH2- C6H2Me2)(N2 C3H4)(C6H2Me3)], the product of ortho methyl C-H bond activation. Other side reactions encountered during the synthesis of new ruthenium alkylidene complexes include the formation of hydridocarbonyl-chloride derivatives in the presence of primary alcohols and the deprotonation of ruthenium vinylcarbene ligands by KOBut. We also evaluate the olefin metathesis activity of NHC-coordinated complexes in representative RCM and ROMP reactions.
- Trnka, Tina M.,Morgan, John P.,Sanford, Melanie S.,Wilhelm, Thomas E.,Scholl, Matthias,Choi, Tae-Lim,Ding, Sheng,Day, Michael W.,Grubbs, Robert H.
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p. 2546 - 2558
(2007/10/03)
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- Improved one-pot synthesis of second-generation ruthenium olefin metathesis catalysts
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One-pot synthesis of second-generation ruthenium olefin metathesis catalysts was discussed. These reactions were used to form C-C bonds. Results showed that imidazolium salt SIMes·HCL affords a higher reaction yield than SIMes·HBF4.
- Jafarpour, Laleh,Hillier, Anna C.,Nolan, Steven P.
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p. 442 - 444
(2008/10/08)
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- Efficient and recyclable monomeric and dendritic Ru-based metathesis catalysts
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Several highly active, recoverable and recyclable Ru-based metathesis catalysts are presented. The crystal structure of Ru complex 5, beating a 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene and styrenyl ether ligand is disclosed. The heterocyclic ligand significantly enhances the catalytic activity, and the styrenyl ether allows for the easy recovery of the Ru complex. Catalyst 5 promotes ring-closing metathesis (RCM) and the efficient formation of various trisubstituted olefins at ambient temperature in high yield within 2 h; the catalyst is obtained in >95% yield after silica gel chromatography and can be used directly in subsequent reactions. Tetrasubstituted olefins can also be synthesized by RCM reactions catalyzed by 5. In addition, the synthesis and catalytic activities of two dendritic and recyclable Ru-based complexes are disclosed (32 and 33). Examples involving catalytic ring-closing, ring-opening, and cross metatheses are presented where, unlike monomer 5, dendritic 33 can be readily recovered.
- Garber, Steven B.,Kingsbury, Jason S.,Gray, Brian L.,Hoveyda, Amir H.
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p. 8168 - 8179
(2007/10/03)
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