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Abou-Ezze K, Llevot A, Taton D. Exploiting the Reversible Dimerization of N-Heterocyclic Carbenes to Access Dynamic Polymer Networks with an Organocatalytic Activity. ACS Macro Lett 2024:1008-1015. [PMID: 39052990 DOI: 10.1021/acsmacrolett.4c00390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
The capability of some N-heterocyclic carbenes (NHCs) to reversibly dimerize is exploited to access dynamic polymer networks. Benzimidazolium motifs serving as NHC precursors have thus been supported onto copolymer chains by reversible addition-fragmentation chain transfer (RAFT) copolymerization of styrene and up to 20 mol % of 4-vinylbenzyl-ethyl-benzimidazolium chloride. Molecular versions of 1,3-dialkyl benzimidazolium salts have been synthesized as models, the deprotonation of which with a strong base yields the NHC dimers in the form of tetraaminoalkenes. The crossover reaction between two distinct NHC homodimers, forming heterodimers, is then evidenced. Applying this deprotonation method to the RAFT-derived copolymers leads to polymer networks with cross-links consisting of labile dimerized NHC motifs. These networks can be subsequently decross-linked using two distinct triggers, namely, a monofunctional NHC precursor as competitor and carbon dioxide (CO2). In the latter case, regeneration of the network occurs by chemically fueling the linear copolymer bearing benzimidazolium motifs with tBuOK in the presence of trace amounts of water. The same networks can also be used as latent precursors of transient polyNHCs to catalyze the benzoin condensation upon heating. The polymer-supported organocatalysts can thus be used in successive catalytic cycles.
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Affiliation(s)
- Karine Abou-Ezze
- Laboratoire de Chimie des Polymères Organiques (LCPO), UMR 5629, Université de Bordeaux, CNRS, Bordeaux-INP, UMR 5629, 16 Av. Pey Berland, 33607 Pessac Cedex, France
| | - Audrey Llevot
- Laboratoire de Chimie des Polymères Organiques (LCPO), UMR 5629, Université de Bordeaux, CNRS, Bordeaux-INP, UMR 5629, 16 Av. Pey Berland, 33607 Pessac Cedex, France
| | - Daniel Taton
- Laboratoire de Chimie des Polymères Organiques (LCPO), UMR 5629, Université de Bordeaux, CNRS, Bordeaux-INP, UMR 5629, 16 Av. Pey Berland, 33607 Pessac Cedex, France
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2
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Maust MC, Blakey SB. Photoredox-Driven Three-Component Coupling of Aryl Halides, Olefins, and O 2. ACS Catal 2024; 14:2582-2587. [PMID: 38384944 PMCID: PMC10877571 DOI: 10.1021/acscatal.3c05988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 01/19/2024] [Accepted: 01/22/2024] [Indexed: 02/23/2024]
Abstract
Modern organic synthesis requires methodologies that bring together abundant feedstock chemicals in a mild and efficient manner. To aid in this effort, we have developed a multicomponent radical hydroxyarylation reaction that utilizes aryl halides, olefins, and O2 as the reaction components. Crucial to this advance was an oxidative, rather than a reductive, approach to aryl radical generation, which enables reaction tolerance to O2. This methodology displays a broad functional group tolerance with a variety of functionalized aryl halides and a broad array of olefins. Development of this methodology enables rapid access to biologically relevant hydroxyaryl products from simple, commercially available starting materials.
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Affiliation(s)
- Mark C. Maust
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Simon B. Blakey
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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Tang K, Brown MR, Risko C, Gish MK, Rumbles G, Pham PH, Luca OR, Barlow S, Marder SR. Beyond n-dopants for organic semiconductors: use of bibenzo[ d]imidazoles in UV-promoted dehalogenation reactions of organic halides. Beilstein J Org Chem 2023; 19:1912-1922. [PMID: 38116245 PMCID: PMC10729154 DOI: 10.3762/bjoc.19.142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 11/28/2023] [Indexed: 12/21/2023] Open
Abstract
2,2'-Bis(4-dimethylaminophenyl)- and 2,2'-dicyclohexyl-1,1',3,3'-tetramethyl-2,2',3,3'-tetrahydro-2,2'-bibenzo[d]imidazole ((N-DMBI)2 and (Cyc-DMBI)2) are quite strong reductants with effective potentials of ca. -2 V vs ferrocenium/ferrocene, yet are relatively stable to air due to the coupling of redox and bond-breaking processes. Here, we examine their use in accomplishing electron transfer-induced bond-cleavage reactions, specifically dehalogenations. The dimers reduce halides that have reduction potentials less cathodic than ca. -2 V vs ferrocenium/ferrocene, especially under UV photoexcitation (using a 365 nm LED). In the case of benzyl halides, the products are bibenzyl derivatives, whereas aryl halides are reduced to the corresponding arenes. The potentials of the halides that can be reduced in this way, quantum-chemical calculations, and steady-state and transient absorption spectroscopy suggest that UV irradiation accelerates the reactions via cleavage of the dimers to the corresponding radical monomers.
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Affiliation(s)
- Kan Tang
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Megan R Brown
- Department of Chemistry & Center for Applied Energy Research (CAER), University of Kentucky, Lexington, Kentucky, 40506, United States
| | - Chad Risko
- Department of Chemistry & Center for Applied Energy Research (CAER), University of Kentucky, Lexington, Kentucky, 40506, United States
| | - Melissa K Gish
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado, 80401, United States
| | - Garry Rumbles
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado, 80401, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States,
| | - Phuc H Pham
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Oana R Luca
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Stephen Barlow
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado, 80401, United States
| | - Seth R Marder
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado, 80401, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States,
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
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Zhao Y, Rollet M, Charles L, Canard G, Gigmes D, Vanelle P, Broggi J. Switching from Single to Simultaneous Free‐Radical and Anionic Polymerization with Enamine‐Based Organic Electron Donors. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Yuxi Zhao
- Aix Marseille Univ CNRS Institut de Chimie Radicalaire (ICR) 13013 Marseille France
| | - Marion Rollet
- Aix Marseille Univ CNRS Institut de Chimie Radicalaire (ICR) 13013 Marseille France
| | - Laurence Charles
- Aix Marseille Univ CNRS Institut de Chimie Radicalaire (ICR) 13013 Marseille France
| | - Gabriel Canard
- Aix Marseille Univ CNRS Centre Interdisciplinaire de Nanoscience de Marseille (CINaM) 13288 Marseille France
| | - Didier Gigmes
- Aix Marseille Univ CNRS Institut de Chimie Radicalaire (ICR) 13013 Marseille France
| | - Patrice Vanelle
- Aix Marseille Univ CNRS Institut de Chimie Radicalaire (ICR) 13013 Marseille France
| | - Julie Broggi
- Aix Marseille Univ CNRS Institut de Chimie Radicalaire (ICR) 13013 Marseille France
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Zhao Y, Rollet M, Charles L, Canard G, Gigmes D, Vanelle P, Broggi J. Switching from Single to Simultaneous Free-Radical and Anionic Polymerization with Enamine-Based Organic Electron Donors. Angew Chem Int Ed Engl 2021; 60:19389-19396. [PMID: 34157792 DOI: 10.1002/anie.202106733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/18/2021] [Indexed: 11/09/2022]
Abstract
Although most monomers can polymerize through different propagation pathways, polymerization-initiating systems that can switch from one mode to another are rare. In this study, we demonstrate that enamine-based organic electron donors (OEDs) constitute the first systems able to initiate either free-radical or anionic polymerization under simple, mild, and safe conditions. While direct electron-transfer reduction of monomers by OEDs results in the initiation of anionic chain-growth polymerization, introduction of a competing oxidant with a higher reduction potential than the monomer switches the former anionic propagation to a clean radical-propagation process. The benefit of this dual-mode activator is highlighted in the synthesis of an interpenetrating polymer network through simultaneous initiation of radical and anionic propagation processes.
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Affiliation(s)
- Yuxi Zhao
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire (ICR), 13013, Marseille, France
| | - Marion Rollet
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire (ICR), 13013, Marseille, France
| | - Laurence Charles
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire (ICR), 13013, Marseille, France
| | - Gabriel Canard
- Aix Marseille Univ, CNRS, Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), 13288, Marseille, France
| | - Didier Gigmes
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire (ICR), 13013, Marseille, France
| | - Patrice Vanelle
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire (ICR), 13013, Marseille, France
| | - Julie Broggi
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire (ICR), 13013, Marseille, France
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Messelberger J, Kumar M, Goodner SJ, Munz D. Wanzlick's equilibrium in tri- and tetraaminoolefins. Org Chem Front 2021. [DOI: 10.1039/d1qo01320c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
How to isolate small carbenes, previously reported to from dimers instantaneously, and how to split triaminoolefins into free carbenes.
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Affiliation(s)
- Julian Messelberger
- Saarland University, Inorganic Chemistry: Coordination Chemistry, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Manoj Kumar
- Saarland University, Inorganic Chemistry: Coordination Chemistry, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Stephen J. Goodner
- Saarland University, Inorganic Chemistry: Coordination Chemistry, Campus C4.1, D-66123 Saarbrücken, Germany
- Friedrich-Alexander Universität Erlangen-Nürnberg, Department of Chemistry and Pharmacy: Chair of Inorganic and General Chemistry, Egerlandstraße 1, D-91058 Erlangen, Germany
| | - Dominik Munz
- Saarland University, Inorganic Chemistry: Coordination Chemistry, Campus C4.1, D-66123 Saarbrücken, Germany
- Friedrich-Alexander Universität Erlangen-Nürnberg, Department of Chemistry and Pharmacy: Chair of Inorganic and General Chemistry, Egerlandstraße 1, D-91058 Erlangen, Germany
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