Ruthenium Carbene Catalysts Research Articles

ChemInform Abstract: Ene—Yne Cross‐Metathesis with Ruthenium Carbene Catalysts

AbstractReview: 87 refs.

Ene–yne cross-metathesis with ruthenium carbene catalysts

Conjugated 1,3-dienes are important building blocks in organic and polymer chemistry. Enyne metathesis is a powerful catalytic reaction to access such structural domains. Recent advances and developments in ene–yne cross-metathesis (EYCM) leading to various compounds of interest and their intermediates, that can directly be transformed in tandem procedures, are reviewed in this article. In addition, the use of bio-resourced olefinic substrates is presented.

後周期遷移金属触媒を用いた置換アセチレン重合の新展開

This article overviews the new aspects of transition metal catalysts for polymerization of substituted acetylene monomers. The activity of rhodium-based catalysts is enhanced by introducing a strongly π-acidic diene ligand, tetrafluorobenzobarrelene (tfb). Precise control of polymerization of phenylacetylenes is achieved by two types of rhodium catalysts bearing tfb. The activity of zwitterionic rhodium-type catalyst is also intensified by the introduction of tfb, which achieves a higher monomer consumption rate than that with the conventional rhodium catalyst. Disubstituted acetylenes with polar functional groups are polymerized by well-defined ruthenium carbene catalyst. Phenylacetylenes having a coordinative substituent at the ortho position on its aromatic ring are efficiently polymerized by the ruthenium carbene catalyst to give the corresponding polymers in high yields.

Enantioseparation of doubly functionalized polar norbornenes by HPLC and their ruthenium-catalyzed ring-opening metathesis polymerization

Doubly fuctionalized polar norbornenes bearing the cyano and ester groups in 2,3-positions are synthesized and enantiomers are separated by high performance liquid chromatography (HPLC) with a chiral stationary phase. These optically active monomers are polymerized by ruthenium carbene catalysts, and high yields of the polymers were obtained. The chiral monomer bearing ethyl ester gave an optically active polymer of lower, but opposite sign of optical rotation (monomer [α]D = +61.0°, polymer [α]D = −3.1°). The circular dichroism (CD) of the obtained chiral polymers gave a Cotton effect. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 485–491, 2010

Poly(7-oxanorbornenes) carrying 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO) radicals: Synthesis and charge/discharge properties

TEMPO-containing 7-oxanorbornene monomers 1–4 (TEMPO=2,2,6,6-tetramethylpiperidine-1-oxy) were synthesized and polymerized via ring-opening metathesis using a ruthenium carbene catalyst. Monomers 1 and 3 gave polymers with number-average weights of 80 100 and 112 200 in 85 and 96% yields, respectively, whereas monomers 2 and 4 did not provide high molecular weight polymers. Poly(1) and poly(3) were soluble in common solvents including CHCl3, CH2Cl2 and THF, while insoluble in hexane, diethyl ether and MeOH. They were thermally stable up to ca. 240°C according to the TGA measurements in air. The secondary batteries utilizing the present polymers as cathode-active material demonstrated reversible charge/discharge processes, whose discharge capacities were 107 and 92.8Ah/kg, and displayed excellent high-rate charge and discharge properties. These cells demonstrated excellent cycle life, e.g., the discharge capacities of poly(1) and poly(3) showed less than 10% decrements even after 100 cycles.

Non‐metathesis reactions of ruthenium carbene catalysts and their application to the synthesis of nitrogen‐containing heterocycles

Non-metathesis reactions of ruthenium carbene catalysts, such as olefin isomerization, hydrogenation, radical reaction, activation of silane, cyclopropanation, epimerization cocyclopropane, [3 + 2] cycloaddition, and cycloisomerization, are summarized. The utility of these reactions was demonstrated by the synthesis of indole using olefin isomerization and subsequent ring-closing metathesis, the synthesis of indoline using cycloisomerization, and the synthesis of the putative structure of fistulosin using cycloisomerization as a key step.

Development of Novel Reactions Using Ruthenium Carbene Catalyst and Its Application to Novel Methods for Preparing Nitrogen‐Containing Heterocycles.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Reduction of Olefins Using Ruthenium Carbene Catalysts and Silanes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.

Reduction of Olefins Using Ruthenium Carbene Catalysts and Silanes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.

Maleates from Diazoacetates and Dilactones from Head‐to‐Head Dimerization of Alkenyl Diazoacetates Using Grubbs′ 2nd‐Generation Ruthenium Carbene Catalyst.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Olefin Metathesis Route to Antiviral Nucleosides

The success of the early nucleoside agents, the toxicity and metabolic instability of many nucleoside analogues and the effects of viral pathogens on public health are driving the design, synthesis and evaluation of new nucleoside analogues. In this context, a powerful reaction has emerged over the past decade that has fundamentally changed the outlook on nucleoside chemistry: the olefin metathesis reaction. This review is designed to give an overview of the synthesis of some nucleosides of biological interest, according to their structural types (e.g., neplanocins and aristeromycin analogues, 2',3'-unsaturated nucleoside analogues, and acyclonucleosides), using metathesis reactions by employing either the alkoxy imido molybdenum catalyst developed by Schrock and various ruthenium carbene catalysts developed by Grubbs, Hoveyda-Grubbs and Nolan.

Reduction of Olefins Using Ruthenium Carbene Catalysts and Silanes

Ruthenium carbene complexes are able to mediate reduction of olefins in the presence of trialkylsilanes. Under these ­reduction conditions, when kinetically favorable ring-closing ­metathesis is possible, a one-pot cyclization-reduction sequence can be performed.

Maleates from diazoacetates and dilactones from head-to-head dimerisation of alkenyl diazoacetates using Grubbs' 2nd-generation ruthenium carbene catalyst

Grubbs' 2nd-generation ruthenium carbene catalyst homocouples diazoacetates to maleates and also catalyses head-to-head dimerisation of alkenyl diazoacetates giving dienyl dilactones.

Cross Enyne Metathesis of para-Substituted Styrenes: A Kinetic Study of Enyne Metathesis

[Reaction: see text] The intermolecular enyne metathesis between alkynes and styrene derivatives was developed to study electronic effects in enyne metathesis. A Hammett plot for the overall reaction, catalyst initiation and vinyl carbene turnover was determined with the second generation Grubbs ruthenium carbene catalyst.

Cycloisomerization promoted by the combination of a ruthenium-carbene catalyst and trimethylsilyl vinyl ether, and its application in the synthesis of heterocyclic compounds: 3-methylene-2,3-dihydroindoles and 3-methylene-2,3-dihydrobenzofurans.

Cycloisomerization promoted by the combination of a ruthenium-carbene catalyst and trimethylsilyl vinyl ether, and its application in the synthesis of heterocyclic compounds: 3-methylene-2,3-dihydroindoles and 3-methylene-2,3-dihydrobenzofurans.

Cycloisomerization Promoted by the Combination of a Ruthenium–Carbene Catalyst and Trimethylsilyl Vinyl Ether, and its Application in The Synthesis of Heterocyclic Compounds: 3‐Methylene‐2,3‐dihydroindoles and 3‐Methylene‐2,3‐dihydrobenzofurans

Substituierte N- und O-Heterocyclen wurden durch Cycloisomerisierung von Dienen mithilfe eines Rutheniumcarben-Katalysators hergestellt. Die mit und ohne Trimethylsilyl(vinyl)ether erhaltenen Produkte sind unterschiedlich (siehe Schema, Cy=Cyclohexyl, Mes=2,4,6-Trimethylphenyl, Ts=para-Toluolsulfonyl).

Mechanism and activity of ruthenium olefin metathesis catalysts: the role of ligands and substrates from a theoretical perspective.

The reaction mechanism of olefin metathesis by ruthenium carbene catalysts is studied by gradient-corrected density functional calculations (BP86). Alternative reaction mechanisms for the reaction of the "first-generation" Grubbs-type catalyst (PCy(3))(2)Cl(2)Ru=CH(2) (1) for the reaction with ethylene are studied. The most likely dissociative mechanism with trans olefin coordination is investigated for the metathesis reaction between the "first-" and the "second-generation" Grubbs-type catalysts 1 and (H(2)IMes)(PCy(3))Cl(2)Ru=CH(2) (2) with different substrates, ethylene, ethyl vinyl ether, and norbornene, and a profound influence of the substrate is found. In contrast to the degenerate reaction with ethylene, the reactions with ethyl vinyl ether and norbornene are strongly exergonic by 8-15 kcal/mol, and this excess energy is released after passing through the metallacyclobutane structure. While the metallacyclobutane is in a deep potential minimum for degenerate metathesis reactions, the energy barrier for the [2+2] cycloreversion vanishes for the most exergonic reactions. On the free energy surface under typical experimental conditions, the rate-limiting steps for the overall reactions are then either metallacyclobutane formation for 1 or phosphane ligand dissociation for 2.

Modular Norbornene Derivatives for the Preparation of Well-Defined Amphiphilic Polymers: Study of the Lipid Membrane Disruption Activities

Novel 2,3-disubstituted-7-alkylidene norborn-2-ene derivatives (1−4) were prepared through Diels−Alder cycloaddition of fulvene derivatives and appropriate dienophiles. The ring-opening metathesis polymerization of this type of modular monomer was studied using a molybdenum alkylidene catalyst (7) and three different ruthenium carbene catalysts (8−10). Through the choice of monomer and catalyst it was possible to obtain polymers with a range of molecular weights and narrow polydispersities (1.08−1.20). The resulting polymers were quantitatively transformed to water-soluble amphiphilic polymers through simple chemical modifications. By changing the monomer structure, it was possible to tune the balance of hydrophobicity and ionic nature of the final polymer. The interaction of these polymers with phospholipid membranes was studied using large unilamellar vesicles that entrap a fluorescent dye. To probe the effect of polymer molecular weight, ionic nature, and hydrophobic character on membrane disruption activity, polymer-induced dye leakage from the large unilamellar vesicles was measured.

A Cross Metathesis Based Protocol for the Effective Synthesis of Function­alised Allyl Bromides and Chlorides

Functionalised allyl halides, useful starting materials for the preparation of substituted organometallic reagents can be simply obtained by a straightforward approach. Hoveyda's ruthenium carbene catalyst 3, used in catalytic amount (2 mol%), is able to promote the cross metathesis of allyl bromide and chloride with a variety of different substituted olefins giving the corresponding functionalised allyl halides in satisfactory yields. trans-Olefins are obtained as major diastereoisomers reaching 90:10 (trans:cis) ratio when allyl chloride is used as the metathesis partner. This reaction represents a simple and accessible way for the preparation of valuable precursors for functionalised organometallic reagents. In particular, the use of functionalised allyl bromides (lOb and 13) in the enantioselective Nozaki-Hiyama reaction promoted by [Cr(Salen)Cl] is presented.

Metathesis Activity and Stability of New Generation Ruthenium Polymerization Catalysts

A kinetic study of three ruthenium carbene catalysts, (H2IPr)(PCy3)(Cl)2RuCHPh, 3 (investigated extensively by Mol), (H2IMes)(Cl)2RuCH(o-iPrOC6H4), 4 (Hoveyda's catalyst), and (H2IPr)(Cl)2RuCH(o-iPrOC6H4), 5 (a new catalyst structure), was conducted under ADMET polymerization conditions. The kinetic behavior of these catalysts was compared to the classical first- and second-generation Grubbs' complexes at 30, 45, and 60 °C. Complex 3 exhibits the highest initial ADMET rate (80 DP s-1) of any phosphine complex to date and efficiently promotes metathesis even at temperatures as low as 0 °C. Complex 4 alone does not polymerize 1,9-decadiene in the bulk; however, addition of a polar solvent induces polymerization. Combining elements of catalysts 3 and 4 yielded the new complex 5. This complex results in higher polycondensation rates than previous Hoveyda-type structures and exhibits an increased stability over its parent phosphine complex. The new catalyst polymerizes 1,9-decadiene in the bulk to high polymer...