Article
Chemistry, Multidisciplinary
Louis Monsigny, Anna Kajetanowicz, Karol Grela
Summary: This review discusses a distinct class of ruthenium olefin metathesis catalysts with unsymmetrical N-heterocyclic carbene (uNHC) ligands, highlighting their advantages such as thermodynamic stability, chemical latency, selectivity, and compatibility with green solvents in specialized metathesis transformations. Despite being niche, uNHC complexes have the potential to be implemented in various industrial processes like valorization of Fischer-Tropsch olefin fractions, ethenolysis of renewable products, and modern pharmaceutical production.
Article
Chemistry, Multidisciplinary
Wioletta Kosnik, Dawid Lichosyt, Marcin Sniezek, Angelika Janaszkiewicz, Krzysztof Wozniak, Maura Malinska, Bartosz Trzaskowski, Anna Kajetanowicz, Karol Grela
Summary: The formation of sterically hindered C-C double bonds through catalytic olefin metathesis is a challenging task for Ru catalysts. To overcome this limitation, a new NHC ligand was designed, which reduced the susceptibility of small-size NHC catalysts to decomposition. The resulting isomeric complexes exhibited similar high thermodynamic stability but different application profiles in catalysis.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Applied
Louis Monsigny, Jakub Piatkowski, Damian Trzybinski, Krzysztof Wozniak, Tomasz Nienaltowski, Anna Kajetanowicz, Karol Grela
Summary: Two new ruthenium complexes, Sil-II and Sil-II', were synthesized and characterized as catalysts for olefin metathesis reactions. Sil-II' showed better stability and productivity compared to Sil-II, and kinetic experiments revealed differences in initiation mechanisms between the two catalysts.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Physical
Adam A. Rajkiewicz, Anna Kajetanowicz, Karol Grela
Summary: New ruthenium olefin metathesis catalysts containing N-heterocyclic carbene (NHC) connected by a linker tether to a benzylidene ligand have been studied. These polymeric catalysts exhibited slightly lower activity compared to structurally related nonpolymeric catalysts, but have been successfully used in a number of ring-closing metathesis reactions to produce various heterocyclic compounds, including biologically and pharmacologically related analogues.
Article
Chemistry, Physical
Peng Ma, Jiaren Zhang, Xiaqian Wu, Jianhui Wang
Summary: Phosphine-free ruthenium benzylidene complexes with imidazole ligands have been reported. These catalysts are effective for high-temperature ring-closing metathesis (RCM) and cross-metathesis (CM) reactions, unlike the commonly used phosphine-containing N-heterocyclic carbene-based ruthenium catalysts which exhibit side reactions. This discovery paves the way for the development of more selective ruthenium metathesis catalysts for reactions requiring harsh conditions.
Article
Chemistry, Multidisciplinary
Juan Pablo Martinez, Miquel Sola, Albert Poater
Summary: The research utilizes nanotechnology in olefin metathesis with homogeneous Ru-NHC catalysts, aiming to change the catalysis of the metal center to increase the steric pressure of C-60 in the first sphere of reactivity. DFT calculations show that SIMes-derived systems are efficient catalysts for olefin metathesis.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Physical
Haoyu Wang, Haitao Yu, Dong Bai, Dan Yao, Yongjun Han, Yichao Shi, Zhiqun Wang
Summary: A ruthenium olefin metathesis catalyst (C1-H) with a novel NHC ligand tethered by an ethoxy-pyridyl arm was synthesized and compared with its methylated derivative (C1-Me). The study showed profound variations in initiation rate, kinetics, metathesis activity, and decomposition behavior between these two catalysts. The remote torsional strain was found to have a considerable influence on the catalytic activity and decomposition behavior of this ligand class.
JOURNAL OF CATALYSIS
(2023)
Article
Biochemistry & Molecular Biology
Stefan Czarnocki, Louis Monsigny, Michal Sienkiewicz, Anna Kajetanowicz, Karol Grela
Summary: A modular and flexible strategy for synthesizing N-heterocyclic carbene (NHC) ligands bearing Bronsted base tags has been proposed and used to prepare two tagged NHC ligands with different acid residues. These tagged NHC ligands serve as an attractive starting point for the synthesis of olefin metathesis ruthenium catalysts with non-dissociating ligands. The impact of the Bronsted base tags on the activity of the obtained olefin metathesis catalysts has been investigated.
Article
Chemistry, Organic
Louis Monsigny, Stefan Czarnocki, Michal Sienkiewicz, William Kopcha, Rene Frankfurter, Carla Vogt, Wladimir Solodenko, Anna Kajetanowicz, Andreas Kirschning, Karol Grela
Summary: Six olefin metathesis catalysts based on a common ruthenium precursor with a hydroxy-substituted N-heterocyclic carbene ligand were successfully prepared and fully characterized. Two of them were directly immobilized on a solid support for proof-of-concept and shown to be efficient and stable for repeated runs. In nonpolar media like n-hexane, the catalytic reactions exhibit truly heterogeneous characteristics with very low ruthenium contamination in the products.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Janis Musso, Jordan De Jesus Silva, Mathis J. Benedikter, Jonas Groos, Wolfgang Frey, Christophe Coperet, Michael R. Buchmeiser
Summary: Recent studies have shown that cationic d(0) group 6 olefin metathesis catalysts exhibit higher activity compared to their neutral counterparts, and their catalytic performance is greatly enhanced by immobilization on silica.
Article
Chemistry, Multidisciplinary
Noy B. Nechmad, Victoria Kobernik, Naziha Tarannam, Ravindra Phatake, Or Eivgi, Sebastian Kozuch, N. Gabriel Lemcoff
Summary: A novel catalyst Ru-S-CF3-I was synthesized with distinct activity and selectivity profiles for olefin metathesis reactions. The combination of photoisomerization and photochemical release of chloride ions allows for a wide scope of photoinduced olefin metathesis reactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Niklas F. Both, Anke Spannenberg, Haijun Jiao, Kathrin Junge, Matthias Beller
Summary: The use of bis(NHC) manganese(I) complexes 3 as catalysts for the hydrogenation of esters was investigated. Various aromatic and aliphatic esters were successfully hydrogenated at mild temperatures and low catalyst loadings using complexes 3 with KHBEt3 as additive, highlighting the efficiency of the novel catalytic system. Additionally, the versatility of the developed catalytic system was demonstrated by the hydrogenation of other substrate classes like ketones, nitriles, N-heteroarenes, and alkenes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Mathis J. Benedikter, Janis V. Musso, Wolfgang Frey, Roman Schowner, Michael R. Buchmeiser
Summary: Despite their excellent selectivities and activities, Mo- and W-based catalysts for olefin metathesis have not been widely used due to their air sensitivity. The synthesized cationic-at-metal molybdenum and tungsten imido alkylidene NHC nitrile complexes are stable in air and can catalyze olefin metathesis reactions without prior activation. The presence of a nitrile ligand is crucial for their stability, while variations in imido and anionic ligands affect reactivities and stability.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Shiyi Yang, Xiang Yu, Yaxu Liu, Michele Tomasini, Lucia Caporaso, Albert Poater, Luigi Cavallo, Catherine S. J. Cazin, Steven P. Nolan, Michal Szostak
Summary: The Suzuki-Miyaura cross-coupling reaction enables the construction of biaryl ketones from inert amide bonds. However, the mechanism of C(acyl)-N bond oxidative addition and catalyst effect in this reaction remain poorly understood. This study investigates the use of [Pd(NHC)(sulfide)Cl-2] catalysts for amide N-C bond activation and presents the reaction development, kinetic studies, and reaction scope. DFT studies were also conducted to gain insight into the mechanism of C(acyl)-N bond oxidative addition and catalyst activation. The results suggest that [Pd(NHC)(sulfide)Cl-2] precatalysts could find application in C(acyl)-X bond activation in organic synthesis and catalysis.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Katarzyna Mlodzikowska-Pienko, Bartosz Trzaskowski
Summary: Computational calculations reveal that the bimolecular coupling mechanism is the favored degradation pathway for cyclic (alkyl)(amino) carbenes (CAACs) and unsymmetrical N-heterocyclic carbenes (uNHCs) catalysts. These catalysts also exhibit higher stability compared to other common catalysts.
Article
Chemistry, Multidisciplinary
Paul Zaby, Jan Blasius, Anna K. Mueller, Steven P. Nolan, Oldamur Holloczki
Summary: The formation mechanism of metal-N-heterocyclic carbene (NHC) complexes from imidazolium salts in the presence of weak bases was investigated through theoretical methods. Quantum chemical calculations revealed that both sodium acetate and trimethylamine facilitate complex formation. Molecular dynamics simulations showed that the ionic nature of the [AuCl2](-) and imidazolium ions, as well as the sodium acetate base, keep these species associated in the reaction mixture through ion pairing. The neutral amine, however, remains mostly separated from the other reaction partners, making it a significantly less effective base.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Editorial Material
Chemistry, Multidisciplinary
Paul Zaby, Jan Blasius, Anna K. K. Mueller, Steven P. P. Nolan, Oldamur Holloczki
Summary: In this issue, Oldamur Hollczki and co-workers from the Universities of Bonn, Ghent and Debrecen are featured on the cover. The image showcases the quest for an ionic base that can combine with the acidic proton of an imidazolium cation to form a carbene complex. For the full article, visit 10.1002/chem.202203636.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Inorganic & Nuclear
Sebastien G. Guillet, Ishfaq Ibni Hashim, Marek Belis, Kristof Van Hecke, Catherine S. J. Cazin, Steven. P. Nolan
Summary: A simple synthetic method for synthesizing various [Rh(acac)(CO)(NHC)] complexes is presented. In situ infrared monitoring provides valuable information on the reaction mechanism, including the identification of a crucial intermediate. Understanding the reaction mechanism has led to the discovery of novel pathways to commonly used congeners.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Sebastien G. Guillet, Aleksei A. Logvinov, Vladislav A. Voloshkin, Ekaterina A. Martynova, Steven P. Nolan
Summary: Researchers report a simple method for the synthesis of azetidines from 2-isoxasoline-3-carboxylates and alkenes, using [Au(cbz)(NHC)] complexes as photocatalysts. The reaction is applicable to a wide range of substrates. Mechanistic studies confirm the energy transfer pathway. This study further expands the potential application of gold catalysts in energy transfer chemistry and catalysis.
Article
Chemistry, Physical
Sylwia Ostrowska, Lorenzo Palio, Agnieszka Czapik, Subhrajyoti Bhandary, Marcin Kwit, Kristof Van Hecke, Steven P. Nolan
Summary: In this study, a synthetic protocol was developed to prepare palladacycle complexes using a mild base and environmentally friendly solvent, with a focus on complexes with backbone-substituted N-heterocyclic carbene ligands. The accessible complexes exhibited high catalytic activity in the Buchwald-Hartwig amination, with low catalyst loading and mild reaction conditions achieved in a green solvent.
Review
Chemistry, Multidisciplinary
Thomas Scattolin, Giovanni Tonon, Eleonora Botter, Sebastien G. Guillet, Nikolaos V. Tzouras, Steven P. Nolan
Summary: The review focuses on the design of gold-based synthons that enable the synthesis of target complexes through simple steps under mild conditions. Mechanistic aspects of their synthesis and reactivity, as well as applications as efficient pre-catalysts, antitumor agents, and photo-emissive materials, are discussed.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Shiyi Yang, Xiang Yu, Yaxu Liu, Michele Tomasini, Lucia Caporaso, Albert Poater, Luigi Cavallo, Catherine S. J. Cazin, Steven P. Nolan, Michal Szostak
Summary: The Suzuki-Miyaura cross-coupling reaction enables the construction of biaryl ketones from inert amide bonds. However, the mechanism of C(acyl)-N bond oxidative addition and catalyst effect in this reaction remain poorly understood. This study investigates the use of [Pd(NHC)(sulfide)Cl-2] catalysts for amide N-C bond activation and presents the reaction development, kinetic studies, and reaction scope. DFT studies were also conducted to gain insight into the mechanism of C(acyl)-N bond oxidative addition and catalyst activation. The results suggest that [Pd(NHC)(sulfide)Cl-2] precatalysts could find application in C(acyl)-X bond activation in organic synthesis and catalysis.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Xinyuan Ma, Steven P. Nolan
Summary: The first-generation ruthenium-indenylidene olefin metathesis complex catalyzes the 1,2-hydrosilylation reaction to produce dihydroquinoline derivatives with high regioselectivity. The complex shows excellent catalytic efficiency when the challenging Ph2SiH2 hydride donor is used. The reaction is efficient with low catalyst loadings and applicable to a wide range of quinoline derivatives and N-heterocycles. A proposed mechanism for this transformation is based on stoichiometric reactions.
Article
Chemistry, Inorganic & Nuclear
Thomas Scattolin, Aleksei A. Logvinov, Nikolaos V. Tzouras, Catherine S. J. Cazin, Steven P. Nolan
Summary: N-heterocyclic carbene (NHC) ligands have evolved from being lab curiosities to important supporting ligands in various fields such as organometallic chemistry, homogeneous catalysis, medicinal chemistry, and materials science.
Article
Chemistry, Inorganic & Nuclear
Sofie M. P. Vanden Broeck, Nikolaos V. V. Tzouras, Marina Saab, Kristof Van Hecke, Busra Dereli, Ida Ritacco, Luigi Cavallo, Georgios C. C. Vougioukalakis, Pierre Braunstein, Steven P. P. Nolan, Andreas A. A. Danopoulos, Catherine S. J. Cazin
Summary: The 4-RN-1,3-Ar-2-imidazolium salt, R = iPr, tBu, Ar = Mes, Dipp, underwent metalation by Au-I at the C2-, C5-, and 4-RN positions, depending on the reactants and conditions used. A rare direct rearrangement of the Au-I aminide to an abnormal imidazol-5-ylidene Au-I complex was also observed, which may involve TfO- facilitated H+ transfer, according to a DFT study.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Multidisciplinary
Sylwia Ostrowska, Pierre Arnaut, David J. Liptrot, Catherine S. J. Cazin, Steven P. Nolan
Summary: The synthesis, isolation, and full characterization of a new copper complex [Cu(IPr)(OC(H)(CF3)(2))] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) are reported. This copper(I) complex is a versatile synthon capable of activating various X-H bonds including C-H, N-H, and S-H bonds. [Cu(IPr)(OC(H)(CF3)(2))] was investigated as a pre-catalyst in several catalytic reactions.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Raphael Gauthier, Nikolaos V. Tzouras, Steven P. Nolan, Jean-Francois Paquin
Summary: The gold-catalyzed hydration of 2,2,2-trifluoroethyl-substituted alkynes exhibits high regioselectivity, resulting in the formation of β-trifluoromethylketones as the major products. This transformation highlights the significant directing effect of the trifluoromethyl group, mediated by its inductive effect, in gold-catalyzed addition to alkynes.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Sebastien Lemouzy, Alienor Delavarde, Frederic Lamaty, Xavier Bantreil, Julien Pinaud, Sylvain Caillol
Summary: The synthesis of a new biobased aromatic diisocyanate from lignocellulosic raw material offers a greener approach for isocyanate production and the polyurethane industry. The conversion of bisguaiacol F into bisguaiacol F diamine was successfully achieved under mechanochemical and microwave conditions. The resulting diisocyanate was synthesized using a phosgene-free/room temperature protocol and showed potential as a biobased alternative to petrochemical-based diisocyanates.
Article
Chemistry, Inorganic & Nuclear
Vladislav A. Voloshkin, Yaxu Liu, Marek Belis, Min Peng, Kristof Van Hecke, Catherine S. J. Cazin, Steven P. Nolan
Summary: The synthesis of novel phosphine palladium PEPPSI and dimer complexes bearing RuPhos, SPhos and XPhos phosphines is reported. The crystal structures of XPhos Pd PEPPSI with pyridine, SPhos Pd PEPPSI with 3-chloropyridine as throw-away ligands and the RuPhos palladium dimer were obtained and compared with previously reported congeners. The catalytic activity of these complexes was examined via a C-N coupling reaction, and it was found that RuPhos complex 2b showed the highest catalytic activity with 97% yield at a low catalyst loading. The addition of 3-pentanone significantly improved the yields of phosphine dimers and PEPPSI complexes when the reactions were performed in THF.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Multidisciplinary
Benon Maliszewski, Eleonora Casillo, Perrine Lambert, Fady Nahra, Catherine Cazin, Steven Nolan
Summary: This article reports an efficient olefin hydrosilylation protocol using Pt(ii)-thioether-based pre-catalysts. These simple and readily available complexes exhibit excellent catalytic performance and offer significant advantages over existing alternatives, enabling rapid and high conversions at ppm-level catalyst loadings.
CHEMICAL COMMUNICATIONS
(2023)