1
|
Lorkowski J, Yorkgitis P, Serrato MR, Gembicky M, Pietraszuk C, Bertrand G, Jazzar R. Genuine carbene versus carbene-like reactivity. Angew Chem Int Ed Engl 2024; 63:e202401020. [PMID: 38632078 DOI: 10.1002/anie.202401020] [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: 01/15/2024] [Revised: 04/14/2024] [Accepted: 04/17/2024] [Indexed: 04/19/2024]
Abstract
Singlet carbenes are not always isolable and often even elude direct detection. When they escape observation, their formation can sometimes be evidenced by in situ trapping experiments. However, is carbene-like reactivity genuine evidence of carbene formation? Herein, using the first example of a spectroscopically characterized cyclic (amino)(aryl)carbene (CAArC), we cast doubt on the most common carbene trapping reactions as sufficient proof of carbene formation.
Collapse
Affiliation(s)
- Jan Lorkowski
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA-92093-0343, USA
| | - Patrick Yorkgitis
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA-92093-0343, USA
| | - Melinda R Serrato
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA-92093-0343, USA
| | - Milan Gembicky
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA-92093-0343, USA
| | - Cezary Pietraszuk
- Faculty of Chemistry, Adam Mickiewicz University, Poznań, Uniwersytetu Poznańskiego 8, 61-614, Poznań, Poland
| | - Guy Bertrand
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA-92093-0343, USA
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA-92093-0343, USA
| |
Collapse
|
2
|
Aysin RR, Galkin KI. Adaptive carbonyl umpolung involving a carbanionic carbene Breslow intermediate: an alternative mechanism for NHC-mediated organocatalysis. Org Biomol Chem 2023; 21:8702-8707. [PMID: 37867444 DOI: 10.1039/d3ob01195j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Herein, we propose a novel mechanistic model for NHC-mediated carbonyl umpolung which involves the formation of a carbanionic carbene Breslow intermediate (CCBI). We have demonstrated theoretically that this reactive intermediate can be formed by inserting an aldehyde into the C4-H position of an N-aryl-substituted imidazolium-derived NHC via the generation of an H-bonded ditopic carbanionic NHC (dcNHC). Our DFT study on benzoin condensation has revealed that the mechanism of polarity inversion proceeding through the CCBI may be more energetically favorable than the classical mechanism of umpolung that uses the C2 carbene position in NHC. The potential existence of the CCBI highlights the dynamic and adaptive nature of NHC-mediated organocatalysis, particularly in relation to carbonyl umpolung. This finding also sheds light on new pathways in organocatalytic transformations employing the ambident reactivity of NHC, which may be particularly attractive for reactions involving furanic aldehydes and sterically encumbered N-aryl-substituted carbenes.
Collapse
Affiliation(s)
- Rinat R Aysin
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ul. Vavilova, 28, 119991 Moscow, Russia
| | - Konstantin I Galkin
- Bauman Moscow State Technical University, 2nd Baumanskaya ul., 5/1, 105005 Moscow, Russia.
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, ul. Leninsky Prospekt, 47, 119991, Moscow, Russia
| |
Collapse
|
3
|
Hussein AA, Ariffin A. Remote Steric and Electronic Effects of N-Heterocyclic Carbene Ligands on Alkene Reactivity and Regioselectivity toward Hydrocupration Reactions: The Role of Expanded-Ring N-Heterocyclic Carbenes. J Org Chem 2023; 88:13009-13021. [PMID: 37649423 DOI: 10.1021/acs.joc.3c01121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
The remote groups in N-heterocyclic carbene (NHC) ligands have a significant influence on metal-catalyzed reactions. We examine how remote bulkiness, electronic groups, and expanded-ring NHCs (ER-NHCs) influence alkene reactivity and regioselectivity toward hydrocupration using density functional theory calculations. The impact of remote steric bulkiness on the Cu-H insertion rate is analyzed, revealing a strong correlation between the steric substituent constant and rate ratio, where a bulky group increases the rate due to reduced steric effects in the transition state (TS). The steric properties of the examined catalysts (with a remote group R2 = CPh3, CHPh2, CH2Ph, CH3, and H) and their corresponding TSs are found to be modulated greatly by the remote steric substitution group and the ring size of the NHC ligand. Enhanced bulkiness enhances the nucleophilic Cu-H moiety. The remote electronic groups have a smaller impact on insertion barrier compared to that of steric hindrance. Furthermore, ER-NHC exploration indicates that NHCs with over five-membered rings have a significantly negative influence on the reaction rate. Finally, with a highly bulky group (R2 = CPh3), anti-Markovnikov insertion preference is attributed to high interaction energy and improved steric properties. Overall, our findings here provide valuable insights for the development of a more effective catalyst in metal-catalyzed reactions.
Collapse
Affiliation(s)
- Aqeel A Hussein
- Department of Medical Laboratory Science, College of Science, Komar University of Science and Technology, Sulaymaniyah, Kurdistan Region 46001, Iraq
- Department of Biology, College of Science, Al-Qasim Green University, Al-Qassim, Babylon 51013, Iraq
| | - Azhar Ariffin
- Department of Chemistry, Faculty of Science, University Malaya, Kuala Lumpur 50603, Malaysia
| |
Collapse
|
4
|
Rowshanpour R, Gravel M, Dudding T. N-Heterocyclic Carbene Organocatalyzed Redox-Active/Ring Expansion Reactions: Mechanistic Insights Unveiling Base Cooperativity. J Org Chem 2022; 87:16785-16793. [DOI: 10.1021/acs.joc.2c02462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Affiliation(s)
- Rozhin Rowshanpour
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario L2S3A1, Canada
| | - Michel Gravel
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N5C9, Canada
| | - Travis Dudding
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario L2S3A1, Canada
| |
Collapse
|
5
|
Wessels A, Klussmann M, Breugst M, Schlörer NE, Berkessel A. Formation of Breslow Intermediates from N‐Heterocyclic Carbenes and Aldehydes Involves Autocatalysis by the Breslow Intermediate, and a Hemiacetal. Angew Chem Int Ed Engl 2022; 61:e202117682. [PMID: 35238462 PMCID: PMC9325009 DOI: 10.1002/anie.202117682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Indexed: 11/23/2022]
Abstract
Under aprotic conditions, the stoichiometric reaction of N‐heterocyclic carbenes (NHCs) such as imidazolidin‐2‐ylidenes with aldehydes affords Breslow Intermediates (BIs), involving a formal 1,2‐C‐to‐O proton shift. We herein report kinetic studies (NMR), complemented by DFT calculations, on the mechanism of this kinetically disfavored H‐translocation. Variable time normalization analysis (VTNA) revealed that the kinetic orders of the reactants vary for different NHC‐to‐aldehyde ratios, indicating different and ratio‐dependent mechanistic regimes. We propose that for high NHC‐to‐aldehyde ratios, the H‐shift takes place in the primary, zwitterionic NHC‐aldehyde adduct. With excess aldehyde, the zwitterion is in equilibrium with a hemiacetal, in which the H‐shift occurs. In both regimes, the critical H‐shift is auto‐catalyzed by the BI. Kinetic isotope effects observed for R‐CDO are in line with our proposal. Furthermore, we detected an H‐bonded complex of the BI with excess NHC (NMR).
Collapse
Affiliation(s)
- Alina Wessels
- Department of Chemistry Organic Chemistry University of Cologne Greinstraße 4 50939 Cologne Germany
| | - Martin Klussmann
- Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1 45470 Mülheim an der Ruhr Germany
- Borchers GmbH Berghausener Straße 100 40764 Langenfeld Germany
| | - Martin Breugst
- Department of Chemistry Organic Chemistry University of Cologne Greinstraße 4 50939 Cologne Germany
| | - Nils E. Schlörer
- Department of Chemistry Organic Chemistry University of Cologne Greinstraße 4 50939 Cologne Germany
| | - Albrecht Berkessel
- Department of Chemistry Organic Chemistry University of Cologne Greinstraße 4 50939 Cologne Germany
| |
Collapse
|
6
|
Zhang N, Yu X, Zhang Y. Recent Advances of Thiamine in Organic Synthesis. Adv Synth Catal 2022. [DOI: 10.1002/adsc.202200098] [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)
- Ning Zhang
- School of Chemistry and Pharmaceutical Engineering Jilin Institute of Chemical Technology Jilin 132022 People's Republic of China
- College of Chemistry Jilin University Changchun 130012 People's Republic of China
| | - Xue Yu
- School of Chemistry and Pharmaceutical Engineering Jilin Institute of Chemical Technology Jilin 132022 People's Republic of China
| | - Yuewei Zhang
- School of Chemistry and Pharmaceutical Engineering Jilin Institute of Chemical Technology Jilin 132022 People's Republic of China
| |
Collapse
|
7
|
Wessels A, Klussmann M, Breugst M, Schlörer NE, Berkessel A. Die Bildung von Breslow‐Intermediaten aus N‐heterocyclischen Carbenen und Aldehyden verläuft autokatalytisch und mit einem Halbacetal als Intermediat. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202117682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Alina Wessels
- Department für Chemie Organische Chemie Universität zu Köln Greinstraße 4 50939 Köln Deutschland
| | - Martin Klussmann
- Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1 45470 Mülheim an der Ruhr Deutschland
- Borchers GmbH Berghausener Straße 100 40764 Langenfeld Deutschland
| | - Martin Breugst
- Department für Chemie Organische Chemie Universität zu Köln Greinstraße 4 50939 Köln Deutschland
| | - Nils E. Schlörer
- Department für Chemie Organische Chemie Universität zu Köln Greinstraße 4 50939 Köln Deutschland
| | - Albrecht Berkessel
- Department für Chemie Organische Chemie Universität zu Köln Greinstraße 4 50939 Köln Deutschland
| |
Collapse
|
8
|
Harnying W, Sudkaow P, Biswas A, Berkessel A. N-Heterocyclic Carbene/Carboxylic Acid Co-Catalysis Enables Oxidative Esterification of Demanding Aldehydes/Enals, at Low Catalyst Loading. Angew Chem Int Ed Engl 2021; 60:19631-19636. [PMID: 34010504 PMCID: PMC8457137 DOI: 10.1002/anie.202104712] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/10/2021] [Indexed: 01/07/2023]
Abstract
We report the discovery that simple carboxylic acids, such as benzoic acid, boost the activity of N-heterocyclic carbene (NHC) catalysts in the oxidative esterification of aldehydes. A simple and efficient protocol for the transformation of a wide range of sterically hindered α- and β-substituted aliphatic aldehydes/enals, catalyzed by a novel and readily accessible N-Mes-/N-2,4,6-trichlorophenyl 1,2,4-triazolium salt, and benzoic acid as co-catalyst, was developed. A whole series of α/β-substituted aliphatic aldehydes/enals hitherto not amenable to NHC-catalyzed esterification could be reacted at typical catalyst loadings of 0.02-1.0 mol %. For benzaldehyde, even 0.005 mol % of NHC catalyst proved sufficient: the lowest value ever achieved in NHC catalysis. Preliminary studies point to carboxylic acid-induced acceleration of acyl transfer from azolium enolate intermediates as the mechanistic basis of the observed effect.
Collapse
Affiliation(s)
- Wacharee Harnying
- Department of Chemistry (Organic Chemistry), University of Cologne, Greinstraße 4, 50939, Cologne, Germany
| | - Panyapon Sudkaow
- Department of Chemistry (Organic Chemistry), University of Cologne, Greinstraße 4, 50939, Cologne, Germany
| | - Animesh Biswas
- Department of Chemistry (Organic Chemistry), University of Cologne, Greinstraße 4, 50939, Cologne, Germany
| | - Albrecht Berkessel
- Department of Chemistry (Organic Chemistry), University of Cologne, Greinstraße 4, 50939, Cologne, Germany
| |
Collapse
|
9
|
Harnying W, Sudkaow P, Biswas A, Berkessel A. N‐Heterocyclic Carbene/Carboxylic Acid Co‐Catalysis Enables Oxidative Esterification of Demanding Aldehydes/Enals, at Low Catalyst Loading. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202104712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Wacharee Harnying
- Department of Chemistry (Organic Chemistry) University of Cologne Greinstraße 4 50939 Cologne Germany
| | - Panyapon Sudkaow
- Department of Chemistry (Organic Chemistry) University of Cologne Greinstraße 4 50939 Cologne Germany
| | - Animesh Biswas
- Department of Chemistry (Organic Chemistry) University of Cologne Greinstraße 4 50939 Cologne Germany
| | - Albrecht Berkessel
- Department of Chemistry (Organic Chemistry) University of Cologne Greinstraße 4 50939 Cologne Germany
| |
Collapse
|
10
|
Alizadeh V, Kirchner B. Molecular level insight into the solvation of cellulose in deep eutectic solvents. J Chem Phys 2021; 155:084501. [PMID: 34470350 DOI: 10.1063/5.0058333] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Deep eutectic solvents as sustainable and new-generation solvents show potential in the field of cellulose dissolution. Although these novel materials are tested for numerous industrial, environmental, and medical applications, little is known about the structural features of cellulose interacting with deep eutectic solvents. In this work, the interplay of cellulose is studied in two deep eutectic solvents: choline acetate mixed with urea and choline chloride mixed with urea using classical molecular dynamics simulations. Dissolution of cellulose in the studied liquids was not observed to be in agreement with experimental work from the literature. However, a slight swelling in the chloride, as compared to the acetate-based solvent, is apparent. A possible rationale might be found in the stronger hydrogen bonding of the chloride anion compared to the acetate anion with the hydrogen atoms of the cellulose. Moreover, chloride approaches the outer glucose units comparatively more, which could be interpreted as the onset of entering and thus dissolving the cellulose as was previously observed. Specific hydrogen bonds between all units are analyzed and discussed in detail.
Collapse
Affiliation(s)
- Vahideh Alizadeh
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstraße 4+6, D-53115 Bonn, Germany
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstraße 4+6, D-53115 Bonn, Germany
| |
Collapse
|
11
|
Schotten C, Bourne RA, Kapur N, Nguyen BN, Willans CE. Electrochemical Generation of
N
‐Heterocyclic Carbenes for Use in Synthesis and Catalysis. Adv Synth Catal 2021. [DOI: 10.1002/adsc.202100264] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
| | - Richard A. Bourne
- School of Chemical and Process Engineering University of Leeds Leeds LS2 9JT UK
| | - Nikil Kapur
- School of Mechanical Engineering University of Leeds Leeds LS2 9JT UK
| | - Bao N. Nguyen
- School of Chemistry University of Leeds Leeds LS2 9JT UK
| | | |
Collapse
|
12
|
Mazars F, Hrubaru M, Tumanov N, Wouters J, Delaude L. Synthesis of Azolium‐2‐dithiocarboxylate Zwitterions under Mild, Aerobic Conditions. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100274] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- François Mazars
- Laboratory of Catalysis MolSys Research Unit Université de Liège Institut de Chimie Organique (B6a) Allée du six Août 13 4000 Liège Belgium
| | - Madalina Hrubaru
- Center for Organic Chemistry “Costin D. Nenitescu” Romanian Academy Spl Independentei Bucureşti, 202B 060023 Bucharest Romania
| | - Nikolay Tumanov
- Department of Chemistry Université de Namur Rue de Bruxelles 61 5000 Namur Belgium
| | - Johan Wouters
- Department of Chemistry Université de Namur Rue de Bruxelles 61 5000 Namur Belgium
| | - Lionel Delaude
- Laboratory of Catalysis MolSys Research Unit Université de Liège Institut de Chimie Organique (B6a) Allée du six Août 13 4000 Liège Belgium
| |
Collapse
|
13
|
Vetica F, Bortolami M, Petrucci R, Rocco D, Feroci M. Electrogenerated NHCs in Organic Synthesis: Ionic Liquids vs Organic Solvents Effects. CHEM REC 2021; 21:2130-2147. [PMID: 33507627 DOI: 10.1002/tcr.202000178] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/08/2021] [Indexed: 12/14/2022]
Abstract
In the last twenty years, N-heterocyclic carbenes (NHCs) have been extensively studied for their application as organocatalysts in stereoselective synthesis as well as ligands for transition metals-promoted synthetic methodologies. Derived mainly from azolium salts, NHCs have demonstrated exceptional versatility in their generation usually performed by deprotonation or reduction (chemical or electrochemical). In particular, the generation of NHC under electrochemical conditions, starting from azolium-based ionic liquids, has proven to be a successful green approach and demonstrated wide applicability in organic synthesis. In this Personal Account, the application of electrogenerated NHCs in organic synthesis will be discussed, with a particular attention to the different reactivity in ionic liquids compared to classical organic solvents.
Collapse
Affiliation(s)
- Fabrizio Vetica
- Department of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Martina Bortolami
- Department of Basic and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, Via Castro Laurenziano 7, 00161, Rome, Italy
| | - Rita Petrucci
- Department of Basic and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, Via Castro Laurenziano 7, 00161, Rome, Italy
| | - Daniele Rocco
- Department of Basic and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, Via Castro Laurenziano 7, 00161, Rome, Italy
| | - Marta Feroci
- Department of Basic and Applied Sciences for Engineering (SBAI), Sapienza University of Rome, Via Castro Laurenziano 7, 00161, Rome, Italy
| |
Collapse
|
14
|
Martynova EA, Tzouras NV, Pisanò G, Cazin CSJ, Nolan SP. The “weak base route” leading to transition metal–N-heterocyclic carbene complexes. Chem Commun (Camb) 2021; 57:3836-3856. [DOI: 10.1039/d0cc08149c] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
N-Heterocyclic carbenes (NHCs) are nowadays ubiquitous in organometallic chemistry and catalysis. A simple synthetic route to these is presented.
Collapse
Affiliation(s)
- Ekaterina A. Martynova
- Department of Chemistry and Centre for Sustainable Chemistry
- Ghent University
- 9000 Gent
- Belgium
| | - Nikolaos V. Tzouras
- Department of Chemistry and Centre for Sustainable Chemistry
- Ghent University
- 9000 Gent
- Belgium
| | - Gianmarco Pisanò
- Department of Chemistry and Centre for Sustainable Chemistry
- Ghent University
- 9000 Gent
- Belgium
| | - Catherine S. J. Cazin
- Department of Chemistry and Centre for Sustainable Chemistry
- Ghent University
- 9000 Gent
- Belgium
| | - Steven P. Nolan
- Department of Chemistry and Centre for Sustainable Chemistry
- Ghent University
- 9000 Gent
- Belgium
| |
Collapse
|