Article
Chemistry, Physical
Valerio Sabatino, Dario Staub, Thomas R. Ward
Summary: The synthesis of N-substituted indoles via ring-closing metathesis of indole precursors with N-terminal alkenes was reported. Good yields (up to 72%) were achieved in aqueous metathesis using commercial catalysts or artificial metalloenzymes. Furthermore, the presence of a second metathesis substrate increased the yield of N-acetylindole.
Article
Chemistry, Multidisciplinary
Ammundi Jayavel Chirranjeevi Padmashrija, Sathananthan Kannadasan, Ponnusamy Shanmugam
Summary: A convenient and efficient synthesis of 3-spiro cycloalkene fused 7-aza-2-indalones has been achieved via ring-closing metathesis (RCM) using Grubbs-II catalyst from 3,3'-di- or N,3,3'-tri-allyl/homoallyl/pentenyl 7-aza-2-indalones. The reaction scope was demonstrated by synthesizing spiro products of various ring sizes (n=5, 7, and 18) with different alkenylation agents as substrates. In addition to typical RCM products, a cross metathesis (CM) product and a macrocyclic, 18-membered bis-spirodiene were also observed.
Article
Chemistry, Physical
Charles Killeen, Jie Liu, Harmen S. S. Zijlstra, Florian Maass, James Piers, Reid Adams, Allen Oliver, J. Scott McIndoe
Summary: Ring-closing metathesis (RCM) is a versatile method for forming cyclic structural elements. Real-time analysis using electrospray ionization mass spectrometry (ESI-MS) was applied to study the RCM reaction, revealing the presence of by-products and the decomposition of the catalyst. Isomerization reactions play a significant role in affecting the yield of the desired product, especially in slow RCM reactions.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Organic
Vachiraporn Ajavakom, Potchanee Pandokrak, Sofia S. Salim, Gamal A. I. Moustafa, Richard K. Bellingham, Joseph T. Hill-Cousins, Anawat Ajavakom, Richard C. D. Brown
Summary: A ring-closing metathesis (RCM) reaction of monobrominated dienes using Grubbs II catalyst was reported, giving moderate to good yields (40-80%) of seven-membered bromoolefins. Attempts to form five-, six-, or eight-membered bromoolefins through RCM were unsuccessful, except for one example that resulted in the formation of a bromomethyl-substituted cyclohexene as a byproduct. The selected bromoolefin RCM products showed utility in Suzuki-Miyaura reactions. Vinylic halide exchange (Br -> Cl) was observed as a side reaction under RCM conditions.
Article
Chemistry, Multidisciplinary
Dmitry S. Belov, Gabriela Tejeda, Charlene Tsay, Konstantin V. Bukhryakov
Summary: Vanadium-based catalysts have been demonstrated to catalyze ring-closing olefin metathesis reactions by well-defined V chloride alkylidene phosphine complexes, exhibiting good functional group tolerance. The properties of the imido group and phosphine were found to play a crucial role in the stability of active intermediates.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Physical
Mona O. Albalawi, Laura Falivene, Abdesslem Jedidi, Osman Osman, Shaaban A. Elroby, Luigi Cavallo
Summary: Ruthenium based catalysts are successful in catalyzing metathesis processes for synthesizing new carbon-carbon bonds. The use of density functional theory (DFT) calculations has significantly contributed to the development of new catalysts by providing fundamental understandings. An in-depth computational study on the binding of anion ligands to the metal has provided key insights on the global properties and reactivity of the catalyst.
MOLECULAR CATALYSIS
(2021)
Article
Chemistry, Physical
Pablo D. Nieres, Victoria A. Vaillard, Juan Zelin, Nicolas I. Neuman, Andres F. Trasarti, Carlos R. Apesteguia, Santiago E. Vaillard
Summary: HG(2) is a reliable and extremely useful catalyst for synthesizing olefins, especially for the self-metathesis reaction of unsaturated fatty acid methyl esters. Silica gel is a promising support for large scale application of HG(2) due to its beneficial characteristics. However, storing the supported catalyst under atmospheric conditions at 298K significantly decreases its activity, which compromises its stability and applicability. Detailed experimental and spectroscopic studies, along with electronic structure calculations, shed light on the catalyst decomposition process.
Article
Chemistry, Multidisciplinary
Nasrin Jahan, Arijit Das, Inul Ansary
Summary: In this study, a simple method for cross-aldol condensation reaction was developed to synthesize two types of compounds, and a series of dibenzo-fused macrocycles were obtained through ring-closing metathesis reaction. The cis/trans configurations of the products were confirmed by H-1-NMR spectral data.
Article
Chemistry, Organic
Fatema Jagot, Songeziwe Ntsimango, Kennedy J. Ngwira, Manuel A. Fernandes, Charles B. de Koning
Summary: This article describes the key steps in the synthesis of derivatives of angucycline, tetrangulol, including the catalyzed SuzukiMiyaura cross-coupling reaction, iron-catalyzed ring-closing carbonyl-olefin metathesis reaction, and late-stage oxidation reaction. The chlorinated compounds were obtained as final products.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Polymer Science
Mohammad Yasir, Andreas F. M. Kilbinger
Summary: Norbornene and cyclohexene show different polymerization behaviors using Grubbs' catalysts due to their varying ring strain energy levels; a sequence-selective cascade polymerization of a monomer containing both rings resulted in polymers with moderate molecular weight dispersities and good control over molecular weight.
Article
Chemistry, Multidisciplinary
Nils Ansmann, Thaddaus Thorwart, Lutz Greb
Summary: The Lewis superacid bis(perchlorocatecholato)silane catalyzes C-O bond metathesis of alkyl ethers with high efficiency, enabling chemoselective ring contractions of macrocyclic crown ethers and unprecedented ring-closing metathesis of polyethylene glycols for polymer-selective degradation.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Physical
Mina Askun, Kutay Sagdic, Fauh Inci, Bengi Ozgun Ozturk
Summary: This study demonstrates that encapsulating homogeneous catalysts in hollow silica gels is an efficient approach to improve the performance and recyclability of ruthenium catalysts in ring-closing metathesis reactions. The resulting catalytic system shows enhanced stability even under an air atmosphere and can maintain its activity for up to 6 months of storage time on the benchtop.
CATALYSIS SCIENCE & TECHNOLOGY
(2022)
Article
Chemistry, Physical
Andre Both, Thomas Roider, Felix Ziegler, Xiulan Xie, Michael R. Buchmeiser, Ulrich Tallarek
Summary: In this study, a 2(nd)-generation Grubbs-Hoveyda type catalyst was immobilized in mesoporous silica and used in the ring-closing metathesis (RCM) of an alpha,omega-diene to a large macro(mono)cycle. The relationship between substrate concentration, reaction time, and overall experiment time on the rate of isomerization under spatial confinement with continuous-flow microreactors was investigated. The results showed that higher substrate concentrations and longer reaction times increased the isomerization rate, while prolonged overall experiment times led to a decline in the isomerization rate.
Article
Chemistry, Organic
Kevin George, Sathananthan Kannadasan
Summary: A sequential synthetic process was developed for the synthesis of quinoline/oxindole appended phenylvinyl-2,5-dihydrofuran derivatives. The process involved multiple steps, starting with nucleophilic addition and O-allylation, followed by ring-closing enyne metathesis. The structures and stereochemistry of the synthesized compounds were confirmed by spectroscopic analysis and XRD studies.
Article
Chemistry, Physical
Ulrich Tallarek, Janika Hochstrasser, Felix Ziegler, Xiaohui Huang, Christian Kubel, Michael R. Buchmeiser
Summary: The study quantified the effects of spatial confinement on hindered transport in mesoporous silica particles using reconstructions of their morphology as geometrical models in diffusion simulations, examining the interactions between tracers and pore space confinement based on the tracer to mean mesopore size ratio. The hindrance factors derived for different ratios quantify the hindrance of diffusion through the materials compared to free diffusion, providing insights into morphology-transport relationships and the immobilization, formation, and transport of key molecular species in ring-closing metathesis.
Review
Chemistry, Multidisciplinary
Mirjam R. Schreier, Xingwei Guo, Bjorn Pfund, Yasunori Okamoto, Thomas R. Ward, Christoph Kerzig, Oliver S. Wenger
Summary: Cyclometalated iridium(III) complexes are widely used in organic light emitting diodes and photocatalysis for solar energy conversion and synthetic organic chemistry. This article introduces the development of water-soluble variants of these complexes and explores their applications in aqueous photochemistry. The water-soluble complexes have been used in enzyme-catalyzed photoredox reactions, photoionization to yield hydrated electrons, and photochemical upconversion. However, the development of water-soluble photocatalysts still lags behind organic solvents.
ACCOUNTS OF CHEMICAL RESEARCH
(2022)
Article
Chemistry, Inorganic & Nuclear
Alina Stein, Alexandria Deliz Liang, Reyhan Sahin, Thomas R. Ward
Summary: The potential of artificial metalloenzymes has increased interest in the design of novel metal-binding sites in proteins. Metal-chelating unnatural amino acids provide a promising solution for engineering active metal sites in a defined way. In this study, four metal-chelating unnatural amino acids were introduced into HaloTag, an attractive scaffold for assembling functional artificial metalloenzymes. By complementation with [(eta(5)-C5H5)Ru(MeCN)(3)](+), HaloTag engineered with 2-amino-3-(8-hydroxyquinolin-5-yl)propanoic acid (HQ-Ala-1) was used to assemble an artificial metalloenzyme for improved allylic deamination.
JOURNAL OF ORGANOMETALLIC CHEMISTRY
(2022)
Correction
Chemistry, Physical
Fadri Christoffel, Nico V. Igareta, Michela M. Pellizzoni, Laura Tiessler-Sala, Boris Lozhkin, Daniel C. Spiess, Agusti Lledos, Jean-Didier Marechal, Ryan L. Peterson, Thomas R. Ward
Article
Chemistry, Multidisciplinary
Corentin Rumo, Alina Stein, Juliane Klehr, Ryo Tachibana, Alessandro Prescimone, Daniel Haussinger, Thomas R. Ward
Summary: The selective functionalization of organic compounds is a versatile tool, and artificial metalloenzymes offer an ideal means to modify inert motifs. In this study, quantum mechanics/molecular mechanics simulations were used to identify target residues for genetic optimization of the artificial metalloenzyme. Double-saturation mutagenesis provided detailed insight on the activity and selectivity, leading to the development of artificial metalloenzymes that efficiently catalyze the formation of β- and γ-lactams.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Jaicy Vallapurackal, Ariane Stucki, Alexandria Deliz Liang, Juliane Klehr, Petra S. Dittrich, Thomas R. Ward
Summary: Droplet microfluidics has great potential for ultrahigh-throughput compartmentalization, making it an attractive tool for directed enzyme evolution. In this study, we developed an approach for ultrahigh-throughput screening of an artificial metalloenzyme using commercially available fluorescence-activated cell sorters. The protocol was validated by screening a large library and the results showed good agreement with a traditional screening method. This finding opens up new possibilities for the directed evolution of enzymes using FACS.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Physical
Maryana Nadirova, Joel Cejas-Sanchez, Rosa Maria Sebastian, Marcin Wiszniewski, Michal J. Chmielewski, Anna Kajetanowicz, Karol Grela
Summary: Two new unsymmetrical N-heterocyclic carbene ligand (uNHC)-based ruthenium complexes with phenolic OH function were synthesized and characterized. The more active complex was immobilized on the metal-organic framework (MOF) solid support (Al)MIL-101-NH2. The catalytic activity of this heterogeneous system was tested, and although it was less active than the corresponding homogeneous catalyst in solution, it could catalyze selected olefin metathesis reactions, demonstrating the concept of immobilizing catalytically active complexes in MOFs using a phenolic tag.
Article
Chemistry, Inorganic & Nuclear
Katarzyna Gajda, Adrian Sytniczuk, Laure Vendier, Bartosz Trzaskowski, Noel Lugan, Anna Kajetanowicz, Stephanie Bastin, Karol Grela, Vincent Cesar
Summary: Three Hoveyda-Grubbs complexes supported by N-(9-alkylfluorenyl)imidazol-2-ylidene ligands were synthesized. The C(sp(3))-H activation of the dangling alkyl group was studied for generating cyclometalated (C,C-NHC) ruthenium complexes for Z-selective olefin metathesis. The methyl derivative led to the expected cyclometalated complex, while no C(sp(2))-H activation of the fluorenyl moiety and no evolution/transformation were observed for the ethyl and benzyl derivatives, respectively. The cyclometalated complex exhibited Z/E stereoselectivity up to 94/6, despite its fragility under catalytic conditions. An unprecedented insertion of the alkylidene moiety into the Ru-C-NHC bond leading to ruthenium N-heterocyclic olefin complexes was also observed and supported by calculations of the corresponding reaction pathway.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Review
Biochemistry & Molecular Biology
Joel Cejas-Sanchez, Anna Kajetanowicz, Karol Grela, Anne-Marie Caminade, Rosa Maria Sebastian
Summary: Dendrimers are highly branched macromolecules with identical terminal functionalities, but there are cases where having two distinct surface functionalities is advantageous. Janus dendrimers, consisting of two dendrimeric wedges terminated by different functionalities, can be created by synthesizing dendrons with complementary core functionalities. This review discusses various techniques used to fabricate phosphorus-based Janus dendrimers and highlights the advantages of phosphorus dendrimers over classic dendrimers, such as easy monitoring of reactions and purity confirmation through P-31 NMR.
Article
Chemistry, Physical
Adrian Sytniczuk, Anna Kajetanowicz, Karol Grela
Summary: Sterically tuned CAAC ligands have led to the development of a new class of catalysts for ethenolysis of methyl oleate with unprecedented productivity. X-ray diffraction analysis revealed a unique spatial arrangement that facilitates substrate coordination and prevents intermediate decomposition.
Article
Chemistry, Physical
Adrian Sytniczuk, Filip Struzik, Vishal Purohit, Karol Grela, Anna Kajetanowicz
Summary: The synthesis of inexpensive 2-isopropyl-6-methylaniline analogues was achieved through the employment of aza-Claisen rearrangement and subsequent reduction of anilines, overcoming the issue of high price and low availability. The obtained aniline derivatives were utilized in the synthesis of lipophilic Hoveyda-Grubbs-type complexes, serving as efficient catalysts in ethenolysis reactions. The complexes with bulky sec-butyl substituent exhibited superior performance compared to the leading catalyst based on 2-isopropyl-6-methylaniline, making them valuable candidates for large-scale industrial production with a TON of up to 192,000.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Physical
Nico V. Igareta, Ryo Tachibana, Daniel C. Spiess, Ryan L. Peterson, Thomas R. Ward
Summary: By anchoring a metal cofactor within a host protein, artificial metalloenzymes can be created that combine the versatility of transition metals with the power of genetic engineering. In this study, a hydrophobic dimerization domain from superoxide dismutase C was engineered onto a streptavidin host-protein to improve second coordination-sphere interactions. The introduction of the dimerization domain resulted in an inversion of configuration and a fivefold increase in catalytic efficiency of the asymmetric transfer hydrogenase.
FARADAY DISCUSSIONS
(2023)
Article
Chemistry, Multidisciplinary
Adrian Sytniczuk, Mariusz Milewski, Michal Dabrowski, Karol Grela, Anna Kajetanowicz
Summary: A set of macrocyclic unsaturated musk compounds were obtained through a high-concentration RCM process, achieved by forming oligomers and then undergoing backbiting metathesis reaction. The process exhibited high selectivity and yielded pure macrocyclic musk products. The reaction conditions were user-friendly and environmentally friendly, using commercially available catalyst and bio-sourced oleic acid substrates.
Article
Chemistry, Multidisciplinary
Adrian Sytniczuk, Filip Struzik, Karol Grela, Anna Kajetanowicz
Summary: A series of tunable CAAC-based ruthenium benzylidene complexes with increased lipophilicity derived from a key substrate for the drug ibuprofen were obtained and tested in various olefin metathesis transformations. The size of the N-aryl moiety was found to be a decisive factor, offering tunability for selecting the best catalyst for specific reactions.
Article
Biochemical Research Methods
Agata Tyszka-Gumkowska, Anna Kajetanowicz, Karol Grela
Summary: This paper describes a protocol for the olefin metathesis of hydrophobic substrates in water emulsions using ruthenium catalysts. The protocol includes the testing of mechanical foaming for emulsification and the use of microwave heating to optimize reaction efficiency. By utilizing low catalyst loading and ensuring simple product isolation, this protocol extends existing aqueous metathesis techniques.
Article
Chemistry, Multidisciplinary
Maryana Nadirova, Adam Zielinski, Maura Malinska, Anna Kajetanowicz
Summary: Two new ruthenium complexes with chelating-ether benzylidene ligands containing a furan moiety were synthesized and characterized. These complexes showed fast reactivity even at low temperatures and exhibited high activity in a variety of reactions, making them suitable candidates for the transformation of complex polyfunctional compounds that require mild reaction conditions.
CHEMISTRY-SWITZERLAND
(2022)
