1
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Ževart T, Pinter B, Lozinšek M, Urankar D, Jansen-van Vuuren RD, Košmrlj J. Towards structurally versatile mesoionic N-heterocyclic olefin ligands and their coordination to palladium, gold, and boron hydride. Dalton Trans 2024; 53:8915-8925. [PMID: 38590282 DOI: 10.1039/d4dt00195h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
We have developed an efficient and versatile approach for the synthesis of a family of 1,2,3-triazole-based mesoionic N-heterocyclic olefin (mNHO) ligands and investigated their coordination to palladium, gold, and boron hydride experimentally and computationally. We reacted mNHOs obtained through deprotonation of the corresponding methylated and ethylated 1,3,4-triaryl-1,2,3-triazolium salts with [Pd(allyl)Cl]2 to give the corresponding [Pd(η3-allyl)Cl(mNHO)] coordination complexes. 13C NMR data revealed the strong σ-donor character of the mNHO ligands, consistent with the calculated bond orders and atom-condensed charges. Furthermore, we also synthesized [AuCl(mNHO)] and a BH3-mNHO adduct by reacting the triazolium salts with AuCl(SMe2) and BH3·THF, respectively. The BH3-mNHO adduct was tested in the reduction of select aldehydes and ketones to alcohols.
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Affiliation(s)
- Tisa Ževart
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI 1000 Ljubljana, Slovenia.
| | - Balazs Pinter
- The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968, USA
| | - Matic Lozinšek
- Jožef Stefan Institute, Jamova cesta 39, SI 1000 Ljubljana, Slovenia
| | - Damijana Urankar
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI 1000 Ljubljana, Slovenia.
| | - Ross D Jansen-van Vuuren
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI 1000 Ljubljana, Slovenia.
| | - Janez Košmrlj
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI 1000 Ljubljana, Slovenia.
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2
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Haug I, Reitz J, Ziane C, Buchmeiser MR, Hansmann MM, Naumann S. Mesoionic N-Heterocyclic Olefins as Initiators for the Lewis Pair Polymerization of Epoxides. Macromol Rapid Commun 2024:e2300716. [PMID: 38497903 DOI: 10.1002/marc.202300716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/14/2024] [Indexed: 03/19/2024]
Abstract
Mesoionic N-heterocyclic olefins (mNHOs) have recently emerged as a novel class of highly nucleophilic and super-basic σ-donor compounds. Making use of these properties in synthetic polymer chemistry, it is shown that a combination of a specific mNHO and a Mg-based Lewis acid (magnesium bis(hexamethyldisilazide), Mg(HMDS)2) delivers poly(propylene oxide) in quantitative yields from the polymerization of the corresponding epoxide (0.1 mol% mNHO loading). The initiation mechanism involves monomer activation by the Lewis acid and direct ring-opening of the monomer by nucleophilic attack of the mNHO, forming a zwitterionic propagating species. Modulation of the mNHO properties is thereby a direct tool to impact initiation efficiency, revealing a sterically unencumbered triazole-derivative as particularly useful. The joint application of mNHOs together with borane-type Lewis acids is also outlined, resulting in high conversions and fast polymerization kinetics. Importantly, while molar mass distributions remain relatively broad, indicating faster propagation than initiation, the overall molar masses are significantly lower than found in the case of regular NHOs, underlining the increased nucleophilicity and ensuing improved initiation efficiency of mNHOs.
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Affiliation(s)
- Iris Haug
- University of Stuttgart, Institute of Polymer Chemistry, 70569, Stuttgart, Germany
| | - Justus Reitz
- TU Dortmund, Faculty for Chemistry and Chemical Biology, 44227, Dortmund, Germany
| | - Célia Ziane
- University of Stuttgart, Institute of Polymer Chemistry, 70569, Stuttgart, Germany
| | - Michael R Buchmeiser
- University of Stuttgart, Institute of Polymer Chemistry, 70569, Stuttgart, Germany
| | - Max M Hansmann
- TU Dortmund, Faculty for Chemistry and Chemical Biology, 44227, Dortmund, Germany
| | - Stefan Naumann
- University of Stuttgart, Institute of Polymer Chemistry, 70569, Stuttgart, Germany
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3
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Khezeli F, Plaisance C. Computational Design of an Electro-Organocatalyst for Conversion of CO 2 into Formaldehyde. J Phys Chem A 2024; 128:1576-1592. [PMID: 38412517 PMCID: PMC10926098 DOI: 10.1021/acs.jpca.3c07806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/02/2024] [Accepted: 02/05/2024] [Indexed: 02/29/2024]
Abstract
Density functional theory calculations employing a hybrid implicit/explicit solvation method were used to explore a new strategy for electrochemical conversion of CO2 using an electro-organocatalyst. A particular structural motif is identified that consists of an electron-rich vicinal enediamine (>N-C═C-N<) backbone, which is capable of activating CO2 by the formation of a C-C bond while subsequently facilitating the transfer of electrons from a chemically inert cathode to ultimately produce formaldehyde. Unlike transition metal-based electrocatalysts, the electro-organocatalyst is not constrained by scaling relations between the formation energies of activated CO2 and adsorbed CO, nor is it expected to be active for the competing hydrogen evolution reaction. The rate-limiting steps are found to occur during two proton-coupled electron transfer (PCET) sequences and are associated with the transfer of a proton from a proton transfer mediator to a carbon atom on the electro-organocatalyst. The difficulty of this step in the second PCET sequence necessitates an electrode potential of -0.85 V vs RHE to achieve the maximum turnover frequency. In addition, it is postulated that the electro-organocatalyst should also be capable of forming long-chain aldehydes by successively carrying out reductive aldol condensation to grow the alkyl chain one carbon at a time.
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Affiliation(s)
- Foroogh Khezeli
- Cain Department
of Chemical
Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Craig Plaisance
- Cain Department
of Chemical
Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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4
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Sun Q, Eitzinger A, Esken R, Antoni PW, Mayer RJ, Ofial AR, Hansmann MM. Pyridinium-Derived Mesoionic N-Heterocyclic Olefins (py-mNHOs). Angew Chem Int Ed Engl 2024; 63:e202318283. [PMID: 38153170 DOI: 10.1002/anie.202318283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/18/2023] [Accepted: 12/20/2023] [Indexed: 12/29/2023]
Abstract
Mesoionic polarization allows access to electron-rich olefins that have found application as organocatalysts, ligands, or nucleophiles. Herein, we report the synthesis and characterization of a series of 3-methylpyridinium-derived mesoionic olefins (py-mNHOs). We used a DFT-supported design concept, which showed that the introduction of aryl groups in the 1-, 2-, 4-, and 6-positions of the heterocyclic core allowed the kinetic stabilization of the novel mesoionic compounds. Tolman electronic parameters indicate that py-mNHOs are remarkably strong σ-donor ligands toward transition metals and main group Lewis acids. Additionally, they are among the strongest nucleophiles on the Mayr reactivity scale. In reactions of py-mNHOs with electron-poor π-systems, a gradual transition from the formation of zwitterionic adducts via stepwise to concerted 1,3-dipolar cycloadditions was observed experimentally and analyzed by quantum-chemical calculations.
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Affiliation(s)
- Qiu Sun
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Andreas Eitzinger
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Robin Esken
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Patrick W Antoni
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Robert J Mayer
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS), CNRS UMR 7006, Université de Strasbourg, 8 Allée Gaspard Monge, 67000, Strasbourg, France
| | - Armin R Ofial
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Max M Hansmann
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
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5
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Eitzinger A, Reitz J, Antoni PW, Mayr H, Ofial AR, Hansmann MM. Pushing the Upper Limit of Nucleophilicity Scales by Mesoionic N-Heterocyclic Olefins. Angew Chem Int Ed Engl 2023; 62:e202309790. [PMID: 37540606 DOI: 10.1002/anie.202309790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 08/06/2023]
Abstract
A series of mesoionic, 1,2,3-triazole-derived N-heterocyclic olefins (mNHOs), which have an extraordinarily electron-rich exocyclic CC-double bond, was synthesized and spectroscopically characterized, in selected cases by X-ray crystallography. The kinetics of their reactions with arylidene malonates, ArCH=C(CO2 Et)2 , which gave zwitterionic adducts, were investigated photometrically in THF at 20 °C. The resulting second-order rate constants k2 (20 °C) correlate linearly with the reported electrophilicity parameters E of the arylidene malonates (reference electrophiles), thus providing the nucleophile-specific N and sN parameters of the mNHOs according to the correlation lg k2 (20 °C)=sN (N+E). With 21
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Affiliation(s)
- Andreas Eitzinger
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Justus Reitz
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Patrick W Antoni
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Armin R Ofial
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Max M Hansmann
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
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6
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G M, Sharma D, Dandela R, Dhayalan V. Synthetic Strategies of N-Heterocyclic Olefin (NHOs) and Their Recent Application of Organocatalytic Reactions and Beyond. Chemistry 2023:e202302106. [PMID: 37605950 DOI: 10.1002/chem.202302106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 08/23/2023]
Abstract
N-heterocyclic olefin (NHO) derivatives have an electron-rich as well as highly polarized carabon-carbon (C=C) double bond because of the electron-donating nature of nitrogen and sulphur atoms. While NHOs have been developing as novel organocatalysts and ligands for transition-metal complexes in various organic compound syntheses, different research groups are currently interested in preparing imidazole and triazolium-based chiral NHO catalysts. Some of them have been used for enantioselective organic transformations, but were still elusive. N-heterocyclic olefins, the alkylidene derivatives of N-heterocyclic carbenes (NHC), have shown promising results as effective promoters for numerous organic syntheses such as asymmetric catalysis, hydroborylation, hydrosilylation, reduction, CO2 sequestration, alkylation, cycloaddition, polymerization and the ring-opening reaction of aziridine and epoxides, esterification, C-F bond functionalization, amine coupling, trifluoromethyl thiolation, amination etc. NHOs catalysts with suitable structures can serve as a novel class of Lewis/Bronsted bases with strong basicity and high nucleophilicity properties.These facts strongly suggest their enormous chemical potential as sustainable catalysts for a wide variety of reactions in synthetic chemistry. The synthesis of NHOs and their properties are briefly reviewed in this article, along with a summary of the imidazole and triazole core of NHOs' most recent catalytic uses.
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Affiliation(s)
- Mahantesh G
- Department of Chemistry, National Institute of Technology Puducherry, Karaikal, 609609, Union Territory Puducherry, India
| | - Deepika Sharma
- Department of Industrial and Engineering Chemistry, Institute of Chemical Technology, Indian oil Odisha Campus, IIT, Kharagpur extension Centre Mouza Samantpuri, Bhubaneswar, 751013, Odisha, India
| | - Rambabu Dandela
- Department of Industrial and Engineering Chemistry, Institute of Chemical Technology, Indian oil Odisha Campus, IIT, Kharagpur extension Centre Mouza Samantpuri, Bhubaneswar, 751013, Odisha, India
| | - Vasudevan Dhayalan
- Department of Chemistry, National Institute of Technology Puducherry, Karaikal, 609609, Union Territory Puducherry, India
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First Synthesis of DBU-Conjugated Cationic Carbohydrate Derivatives and Investigation of Their Antibacterial and Antifungal Activity. Int J Mol Sci 2023; 24:ijms24043550. [PMID: 36834964 PMCID: PMC9968064 DOI: 10.3390/ijms24043550] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/31/2023] [Accepted: 02/07/2023] [Indexed: 02/12/2023] Open
Abstract
The emergence of drug-resistant bacteria and fungi represents a serious health problem worldwide. It has long been known that cationic compounds can inhibit the growth of bacteria and fungi by disrupting the cell membrane. The advantage of using such cationic compounds is that the microorganisms would not become resistant to cationic agents, since this type of adaptation would mean significantly altering the structure of their cell walls. We designed novel, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene)-derived amidinium salts of carbohydrates, which may be suitable for disturbing the cell walls of bacteria and fungi due to their quaternary ammonium moiety. A series of saccharide-DBU conjugates were prepared from 6-iodo derivatives of d-glucose, d-mannose, d-altrose and d-allose by nucleophilic substitution reactions. We optimized the synthesis of a d-glucose derivative, and studied the protecting group free synthesis of the glucose-DBU conjugates. The effect of the obtained quaternary amidinium salts against Escherichia coli and Staphylococcus aureus bacterial strains and Candida albicans yeast was investigated, and the impact of the used protecting groups and the sugar configuration on the antimicrobial activity was analyzed. Some of the novel sugar quaternary ammonium compounds with lipophilic aromatic groups (benzyl and 2-napthylmethyl) showed particularly good antifungal and antibacterial activity.
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8
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Borbás A, Herczeg M, Demeter F, Bényei A. Synthesis of the Three Most Expensive l-Hexose Thioglycosides from d-Glucose. SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/s-0042-1751394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
AbstractThe biologically important l-hexoses, which are less widespread than d-hexoses, cannot be obtained from natural sources or can only be extracted very costly. Due to the complexity of their synthesis, their commercially available derivatives (which are sold mostly in free form) are also very expensive, which is further exacerbated by the current rapid rise in prices. In the present work, starting from the cheapest d-hexose, d-glucose, using inexpensive and readily available chemicals, a reaction pathway was developed in which the three most expensive l-hexoses (l-idose, l-altrose, and l-talose) were successfully prepared in orthogonally protected thioglycoside form, ready for glycosylation. The l-ido and l-talo derivatives were synthesized by C-5 epimerization of the corresponding 5,6-unsaturated thioglycosides. From the l-ido derivatives, the orthogonally protected thioglycosides of l-altrose were then prepared by C-4 epimerization. Different approaches to the preparation of the key intermediates, 5,6-unsaturated thioglycoside derivatives, were systematically investigated in the presence of various protecting groups (ether and ester) and using commercially available reagents.
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Affiliation(s)
- Anikó Borbás
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Debrecen
| | - Mihály Herczeg
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Debrecen
- Research Group for Oligosaccharide Chemistry of Hungarian Academy of Sciences, ELKH
| | - Fruzsina Demeter
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Debrecen
| | - Attila Bényei
- Laboratory for X-ray Diffraction, Department of Physical Chemistry, University of Debrecen
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9
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Wang S, Zhang C, Li D, Zhou Y, Su Z, Feng X, Dong S. New chiral N-heterocyclic olefin bifunctional organocatalysis in α-functionalization of β-ketoesters. Sci China Chem 2022. [DOI: 10.1007/s11426-022-1458-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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10
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Abstract
This Perspective article highlights the recent development of mesoionic N-heterocyclic olefins (mNHOs), where the exo-cyclic olefinic carbon is not bonded to strongly electron-withdrawing groups. The unquenched basicity and nucleophilicity of the exo-cyclic olefinic carbon make mNHOs strong σ-donors and enable unique reactivity patterns.
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Affiliation(s)
- Qiuming Liang
- Davenport Chemical Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada, M5S 3H6.
| | - Datong Song
- Davenport Chemical Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada, M5S 3H6.
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11
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Synthesis of Four Orthogonally Protected Rare l-Hexose Thioglycosides from d-Mannose by C-5 and C-4 Epimerization. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27113422. [PMID: 35684360 PMCID: PMC9182441 DOI: 10.3390/molecules27113422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 05/20/2022] [Accepted: 05/20/2022] [Indexed: 01/30/2023]
Abstract
l-Hexoses are important components of biologically relevant compounds and precursors of some therapeuticals. However, they typically cannot be obtained from natural sources and due to the complexity of their synthesis, their commercially available derivatives are also very expensive. Starting from one of the cheapest d-hexoses, d-mannose, using inexpensive and readily available chemicals, we developed a reaction pathway to obtain two orthogonally protected l-hexose thioglycoside derivatives, l-gulose and l-galactose, through the corresponding 5,6-unsaturated thioglycosides by C-5 epimerization. From these derivatives, the orthogonally protected thioglycosides of further two l-hexoses (l-allose and l-glucose) were synthesized by C-4 epimerization. The preparation of the key intermediates, the 5,6-unsaturated derivatives, was systematically studied using various protecting groups. By the method developed, we are able to produce highly functionalized l-gulose derivatives in 9 steps (total yields: 21–23%) and l-galactose derivatives in 12 steps (total yields: 6–8%) starting from d-mannose.
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12
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Kuciński K, Stachowiak-Dłużyńska H, Hreczycho G. Catalytic silylation of O–nucleophiles via Si–H or Si–C bond cleavage: A route to silyl ethers, silanols and siloxanes. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214456] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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13
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Watson I, Zhou Y, Ferguson M, Rivard E. Group 4 Transition Metal Complexes with Anionic N‐Heterocyclic Olefin Ligands. Z Anorg Allg Chem 2022. [DOI: 10.1002/zaac.202200082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | | | | | - Eric Rivard
- University of Alberta Deptm. of Chemistry 11227 Saskatchewan Dr. T6G 2G2 Edmonton CANADA
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14
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Guthardt R, Mellin J, Bruhn C, Siemeling U. 1,1′‐Ferrocenylene‐Bridged Bis(N‐Heterocyclic Olefin) Derivatives. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Robin Guthardt
- Institut für Chemie Universität Kassel Heinrich-Plett-Straße 40 34132 Kassel Germany
| | - Johanna Mellin
- Institut für Chemie Universität Kassel Heinrich-Plett-Straße 40 34132 Kassel Germany
| | - Clemens Bruhn
- Institut für Chemie Universität Kassel Heinrich-Plett-Straße 40 34132 Kassel Germany
| | - Ulrich Siemeling
- Institut für Chemie Universität Kassel Heinrich-Plett-Straße 40 34132 Kassel Germany
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15
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Vermersch F, Yazdani S, Junor GP, Grotjahn DB, Jazzar R, Bertrand G. Stable Singlet Carbenes as Organic Superbases. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202111588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- François Vermersch
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
| | - Sima Yazdani
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
- Department of Chemistry and Biochemistry San Diego State University 5500 Campanile Drive San Diego CA 92182-1030 USA
| | - Glen P. Junor
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
| | - Douglas B. Grotjahn
- Department of Chemistry and Biochemistry San Diego State University 5500 Campanile Drive San Diego CA 92182-1030 USA
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
| | - Guy Bertrand
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
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16
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Vermersch F, Yazdani S, Junor GP, Grotjahn DB, Jazzar R, Bertrand G. Stable Singlet Carbenes as Organic Superbases. Angew Chem Int Ed Engl 2021; 60:27253-27257. [PMID: 34729888 DOI: 10.1002/anie.202111588] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/18/2021] [Indexed: 11/10/2022]
Abstract
A simple experimental procedure for scaling carbene Brønsted basicity is described. The results highlight the strong basicity of pyrazol-4-ylidenes, a type of mesoionic carbene, also named cyclic-bentallenes (CBA). They are more basic (pKaH >42.7 in acetonitrile) than the popular proazaphosphatrane Verkade bases, and even the Schwesinger phosphazene superbase P4 (t Bu). The basicity of these compounds can readily be tuned, and they are accessible in multigram quantities. These results open new avenues for carbon centered superbases.
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Affiliation(s)
- François Vermersch
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Sima Yazdani
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA.,Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-1030, USA
| | - Glen P Junor
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Douglas B Grotjahn
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-1030, USA
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Guy Bertrand
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
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17
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Ando S, Ohara A, Ohwada T, Ishizuka T. Rhodium and Palladium Complexes of N-Heterocyclic Olefin (NHO) Ligand Fused with the 9,10-Dihydro-9,10-ethanoanthracene Framework. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shin Ando
- Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi Chuo-ku, Kumamoto 862-0973, Japan
| | - Akio Ohara
- School of Pharmacy, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Tomohiko Ohwada
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tadao Ishizuka
- Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi Chuo-ku, Kumamoto 862-0973, Japan
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Huang S, Wang Y, Hu C, Yan X. Nucleophilic Activation of Sulfur Hexafluoride by N-Heterocyclic Carbenes and N-Heterocyclic Olefins: A Computational Study. Chem Asian J 2021; 16:2687-2693. [PMID: 34320272 DOI: 10.1002/asia.202100770] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/26/2021] [Indexed: 11/10/2022]
Abstract
Sulfur hexafluoride (SF6 ) is considered as a potent greenhouse gas, whose effective degradation is challenging. Here we report a computational study on the nucleophilic activation of sulfur hexafluoride by N-heterocyclic carbenes and N-heterocyclic olefins. The result shows that the activation of SF6 is both thermodynamically and kinetically favorable at mild condition using NHOs with fluoro-substituted azolium and sulfur pentafluoride anion being formed. The Gibbs free energy barrier during the activation of SF6 has a linear relationship with the energy of HOMO of substrates, which could be a guideline for applying those compounds that feature higher energy in HOMO to activate SF6 in high efficiency.
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Affiliation(s)
- Shiqing Huang
- Department of Chemistry, Renmin University of China, Beijing, 100872, P. R. China
| | - Yedong Wang
- Department of Chemistry, Renmin University of China, Beijing, 100872, P. R. China
| | - Chubin Hu
- Department of Chemistry, Renmin University of China, Beijing, 100872, P. R. China
| | - Xiaoyu Yan
- Department of Chemistry, Renmin University of China, Beijing, 100872, P. R. China
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Balint A, Naumann S. A comparison of zwitterionic and anionic mechanisms in the dual-catalytic polymerization of lactide. Polym Chem 2021. [DOI: 10.1039/d1py00992c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Two different polymerization mechanisms for lactide are selectivity addressed to illuminate the respective role of organobase and Lewis acid component.
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Affiliation(s)
- Alexander Balint
- University of Stuttgart, Institute of Polymer Chemistry, 70569 Stuttgart, Germany
| | - Stefan Naumann
- University of Stuttgart, Institute of Polymer Chemistry, 70569 Stuttgart, Germany
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Zhou L, Wang Z, Xu G, Lv C, Wang Q. Structure and activity relationship studies of N-heterocyclic olefin and thiourea/urea catalytic systems: application in ring-opening polymerization of lactones. Polym Chem 2021. [DOI: 10.1039/d0py01747g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Structure–activity relationship studies of N-heterocyclic olefin and thiourea/urea catalytic systems were performed and applied to ROP of lactones.
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Affiliation(s)
- Li Zhou
- Key Laboratory of Biobased Materials
- Qingdao Institute of Bioenergy and Bioprocess Technology
- Chinese Academy of Sciences
- Qingdao
- China
| | - Zhenyu Wang
- Key Laboratory of Biobased Materials
- Qingdao Institute of Bioenergy and Bioprocess Technology
- Chinese Academy of Sciences
- Qingdao
- China
| | - Guangqiang Xu
- Key Laboratory of Biobased Materials
- Qingdao Institute of Bioenergy and Bioprocess Technology
- Chinese Academy of Sciences
- Qingdao
- China
| | - Chengdong Lv
- Key Laboratory of Biobased Materials
- Qingdao Institute of Bioenergy and Bioprocess Technology
- Chinese Academy of Sciences
- Qingdao
- China
| | - Qinggang Wang
- Key Laboratory of Biobased Materials
- Qingdao Institute of Bioenergy and Bioprocess Technology
- Chinese Academy of Sciences
- Qingdao
- China
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