- In a Quest for Selectivity Paired with Activity: A Ruthenium Olefin Metathesis Catalyst Bearing an Unsymmetrical Phenanthrene-Based N-Heterocyclic Carbene
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Robust, selective, and stable in the presence of ethylene, ruthenium olefin metathesis pre-catalyst, {[3-benzyl-1-(10-phenyl-9-phenanthryl)]-2-imidazolidinylidene}dichloro(o-isopropoxyphenylmethylene)ruthenium(II), Ru-3, bearing an unsymetrical N-heterocyclic carbene (uNHC) ligand, has been synthesized. The initiation rate of Ru-3 was examined by ring-closing metathesis and cross-metathesis reactions with a broad spectrum of olefins, showing an unprecendented selectivity. It was also tested in industrially relevant ethenolysis reactions of olefinic substrates from renewable feedstock with very good yields and selectivities.
- D?browski, Micha?,Grela, Karol,Trzybiński, Damian,Wo?niak, Krzysztof,Wyr?bek, Przemys?aw
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- Improved preparation of an olefin metathesis catalyst bearing quaternary ammonium tag (FixCat) and its use in ethenolysis and macrocyclization reactions after immobilization on metal-organic framework (MOF)
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An optimized synthesis of a key intermediate Ru4 in substantially improved yield of 50% and in scale up to 1 gram was described. Such obtained Ru4 was quantitatively converted into useful quaternary ammonium tagged catalyst Ru1 (FixCat) and immobilized in a metal-organic framework (MOF). Next, two challenging applications, not studied previously with hybrid Ru1@MOF catalyst were attempted. In the case of the RCM reaction yielding a macrocyclic musk lactone, heterogeneous Ru1@MOF exhibited under high-dilution conditions high resistance towards unwanted C-C double bond migration, thus offering superior selectivity as compared to analogous homogeneous catalysts. In ethenolysis of ethyl oleate, Ru1@MOF exhibited only slightly better selectivity as compared to well-known general-purpose Hoveyda-Grubbs SIMes and SIPr catalysts, while it was not able to challenge the benchmark Bertrand-Hoveyda-Grubbs catalyst in this transformation.
- Milewski, Mariusz,Kajetanowicz, Anna,Grela, Karol
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- Specialized ruthenium olefin metathesis catalysts bearing bulky unsymmetrical NHC Ligands: Computations, synthesis, and application
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Second-generation ruthenium olefin metathesis catalysts were investigated with systematic variation of the unsymmetrical uNHC ligands. Depending on the uNHC steric bulk, the catalysts exhibited different activity and selectivity in metathesis reactions. DFT calculations and X-ray crystallographic data were used to understand the influence of uNHC ligand structure on the catalyst properties. Furthermore, the catalysts were examined in the context of reactions that are problematic for general-purpose Ru catalysts, including industrially important self-cross metathesis of α-olefins and ethenolysis of ethyl oleate.
- Ma?ecki, Pawe?,Gajda, Katarzyna,Gajda, Roman,Wo?niak, Krzysztof,Trzaskowski, Bartosz,Kajetanowicz, Anna,Grela, Karol
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p. 587 - 598
(2019/01/08)
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- A Gentler Touch: Synthesis of Modern Ruthenium Olefin Metathesis Catalysts Sustained by Mechanical Force
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Mechanochemical synthesis of nine contemporary ruthenium catalysts used for olefin metathesis is described, being the first reported example of formation of Ru carbene organometallic complexes in solid state. Three key organometallic transformations commonly used in the synthesis of the second and third generations of Ru catalysts in solution—phosphine ligand (PCy3) exchange with in situ formed N-heterocyclic carbene (NHC) ligand, PCy3 to pyridine ligand replacement, and benzylidene ligands interchange—were proved to work under mechanochemical conditions, affording the targets in high purity. Mechanochemical approach not only requires less amounts of organic solvent (null for synthesis, only for purification) and is scalable, but also allows for transformations that were reported impossible in the solution phase.
- Mukherjee, Nirmalya,Marczyk, Anna,Szczepaniak, Grzegorz,Sytniczuk, Adrian,Kajetanowicz, Anna,Grela, Karol
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p. 5362 - 5369
(2019/11/11)
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- NOVEL RUTHENIUM COMPLEX, METHOD OF ITS PRODUCTION AND ITS USE IN REACTION OF OLEFINE METATHESIS
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The invention relates to novel ruthenium complexes of formula (9). The invention also relates to the method for preparation of novel metal complexes of formula (9) and their use in olefin metathesis reactions.
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Page/Page column 29-30
(2018/06/22)
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- Stable ruthenium olefin metathesis catalysts bearing symmetrical NHC ligands with primary and secondary: N -alkyl groups
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Four novel stable Hoveyda-Grubbs-type catalysts containing N,N′-dineopentyl- and N,N′-dicyclohexyl-substituted N-heterocyclic carbene (NHC) ligands with syn and anti phenyl groups on the ring backbone were synthesized and fully characterized. The catalytic potential of these complexes was investigated in metathesis reactions of both standard and renewable substrates. Compared to the Hoveyda-Grubbs second generation catalyst (HGII), all of the new catalysts showed high performances in most of the examined metathesis transformations. In particular, N,N′-dicyclohexyl catalysts gave improved results in the challenging ring-closing metathesis (RCM) reaction to form tetrasubstituted olefins, while catalysts with neopentyl N-groups were found to be more active and Z-selective in cross-metathesis (CM) reactions. Modest enantioselectivities in the asymmetric ring-closing metathesis (ARCM) of achiral trienes with different steric hindrance were observed in the presence of catalysts bearing chiral C2-symmetric NHC ligands.
- Ambrosio, Chiara,Paradiso, Veronica,Costabile, Chiara,Bertolasi, Valerio,Caruso, Tonino,Grisi, Fabia
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supporting information
p. 6615 - 6627
(2018/05/23)
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- Expanding the Family of Hoveyda-Grubbs Catalysts Containing Unsymmetrical NHC Ligands
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A series of Hoveyda-Grubbs second-generation catalysts containing N-alkyl/N′-aryl N-heterocyclic carbene (NHC) ligands were synthesized and investigated in representative olefin metathesis reactions. Steric perturbations of unsymmetrical NHCs were achieved through modulation of the hindrance of alkyl (neopentyl, neophyl, cyclohexyl) and aryl (2-isopropylphenyl, mesityl) substituents at the nitrogen atoms in combination with different backbone configurations (syn and anti). The NHC substitution patterns strongly influence the stability and reactivity of the corresponding complexes. In general, complexes bearing an anti NHC backbone are more stable and more active than their corresponding syn isomers. In both the series, the presence of bulky, highly branched N-alkyl groups tends to give reduced catalytic differences between syn and anti isomers, whereas the nature of the N′-aryl substituent (2-isopropylphenyl or mesityl) gives rise to different activity and/or selectivity. Of note, an N′-mesityl catalyst with anti backbone was found to be highly competent in the ethenolysis of ethyl oleate, achieving up to 90% selectivity for the formation of terminal olefins.
- Paradiso, Veronica,Bertolasi, Valerio,Costabile, Chiara,Caruso, Tonino,D?browski, Micha?,Grela, Karol,Grisi, Fabia
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p. 3692 - 3708
(2017/10/13)
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- IMMOBILIZED METAL ALKYLIDENE CATALYSTS AND USE THEREOF IN OLEFIN METATHESIS
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The invention relates to immobilized metal alkylidene catalysts. The catalysts are useful in olefin metathesis.
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Paragraph 00274; 00275
(2017/07/14)
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- Synthesis and catalytic activity of ruthenium indenylidene complexes bearing unsymmetrical NHC containing a heteroaromatic moiety
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New robust and air stable ruthenium(ii) indenylidene second generation olefin metathesis catalysts with unsymmetrical N-heterocyclic carbene (NHC) ligands were synthesized. Model metathesis reactions were performed in the presence of newly-developed complexes in commercial grade toluene under air, leading to high conversions and good selectivities.
- Smoleń, Micha?,Ko?nik, Wioletta,Loska, Rafa?,Gajda, Roman,Malińska, Maura,Wo?niak, Krzysztof,Grela, Karol
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p. 77013 - 77019
(2016/08/30)
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- RUTHENIUM COMPLEXES, METHOD OF PRODUCING THEM, AND THEIR USE
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The subject of the present invention are novel ruthenium complexes defined by the general Formula 1. The present invention also relates to method of manufacturing of a novel metal complexes defined by the general Formula 1 as well as their use in olefin metathesis reactions.
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Page/Page column 36
(2016/07/05)
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- N-Trifluoromethyl NHC Ligands Provide Selective Ruthenium Metathesis Catalysts
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We report the synthesis of ruthenium metathesis catalysts containing unsymmetrical N-trifluoromethyl NHC ligands. These complexes have been fully characterized, and a Ru-F interaction has been identified in the solid state by X-ray crystallographic analysis for three catalysts with Ru-F distances between 2.629(2) and 2.652(2) ?. The influence of the N-trifluoromethyl NHC ligands on the initiation rates and activation parameters was studied. The activity of these catalysts was evaluated in benchmark olefin metathesis reactions and compared to the standard second-generation Grubbs catalyst. Remarkably, N-trifluoromethyl catalysts display an unusually high selectivity for the formation of terminal olefins (up to 90%) in the ethenolysis of ethyl oleate. Much improved selectivity is demonstrated for alternating copolymerization of cyclooctene and norbornene as well. These results underline the importance of electronic effects exerted by the NHC ligand.
- Engl, Pascal S.,Fedorov, Alexey,Copéret, Christophe,Togni, Antonio
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p. 887 - 893
(2016/04/19)
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