1
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Kohl SJ, Sigmund LM, Schmitt M, Greb L. Nitrogen monoxide and calix[4]pyrrolato aluminate: structural constraint enabled NO dimerization. Chem Sci 2024; 15:10803-10809. [PMID: 39027292 PMCID: PMC11253113 DOI: 10.1039/d4sc02378a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 06/15/2024] [Indexed: 07/20/2024] Open
Abstract
The dimerization of nitrogen monoxide (NO) is highly relevant in homo- and heterogeneous biochemical and environmental redox processes, but a broader understanding is challenged by the endergonic nature of this equilibrium. The present work describes NO-dimerization leveraged by structurally constrained aluminum and metal-ligand cooperativity at the anionic calix[4]pyrrolato aluminate(III). Quantum chemical calculations reveal the driving force for N-N bond formation, while reactivity tests shed light on subsequent redox chemistry and NO decomposition at metal surfaces. Inhibiting the dimerization pathway by saturating NO's unpaired electron with a phenyl group (nitrosobenzene) allows trapping the 1,2-adduct as a key intermediate. Elevated temperatures result in an unprecedented and high-yielding rearrangement of the calix[4]pyrrolato ligand scaffold. Kinetic and theoretical studies provide a comprehensive picture of the rearrangement mechanism and delineate systematics for ring modification of the prominent calix[4]pyrrole macrocycle.
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Affiliation(s)
- Senta J Kohl
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Lukas M Sigmund
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Manuel Schmitt
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Lutz Greb
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
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2
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Zubkov MO, Dilman AD. Radical reactions enabled by polyfluoroaryl fragments: photocatalysis and beyond. Chem Soc Rev 2024; 53:4741-4785. [PMID: 38536104 DOI: 10.1039/d3cs00889d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Polyfluoroarenes have been known for a long time, but they are most often used as fluorinated building blocks for the synthesis of aromatic compounds. At the same time, due to peculiar fluorine effect, they have unique properties that provide applications in various fields ranging from synthesis to materials science. This review summarizes advances in the radical chemistry of polyfluoroarenes, which have become possible mainly with the advent of photocatalysis. Transformations of the fluorinated ring via the C-F bond activation, as well as use of fluoroaryl fragments as activating groups and hydrogen atom transfer agents are discussed. The ability of fluoroarenes to serve as catalysts is also considred.
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Affiliation(s)
- Mikhail O Zubkov
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation.
| | - Alexander D Dilman
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation.
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3
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Frenette BL, Rivard E. Frustrated Lewis Pair Chelation in the p-Block. Chemistry 2023; 29:e202302332. [PMID: 37677126 DOI: 10.1002/chem.202302332] [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: 07/20/2023] [Revised: 09/06/2023] [Accepted: 09/07/2023] [Indexed: 09/09/2023]
Abstract
Frustrated Lewis pairs (FLPs) have been the subject of considerable study since the field's inception. While much of the research into FLPs has centered around small molecule activation for diverse stoichiometric and catalytic transformations, intramolecular FLPs also show promise as chelating ligands. The cooperative action of Lewis basic and acidic moieties enables intramolecular FLPs to stabilize low oxidation state centers and (consequently) reactive molecular fragments through a donor-acceptor approach, making them an attractive ligand class in main group element chemistry. This review outlines the state of FLP chelation to date throughout the p-block, encompassing primarily groups 13-16.
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Affiliation(s)
- Brandon L Frenette
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada
| | - Eric Rivard
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada
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4
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Abstract
Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R1R2N-O•. The spin distribution over the nitroxide N and O atoms contributes to the thermodynamic stability of these radicals. The presence of bulky N-substituents R1 and R2 prevents nitroxide radical dimerization, ensuring their kinetic stability. Despite their reactivity toward various transient C radicals, some nitroxides can be easily stored under air at room temperature. Furthermore, nitroxides can be oxidized to oxoammonium salts (R1R2N═O+) or reduced to anions (R1R2N-O-), enabling them to act as valuable oxidants or reductants depending on their oxidation state. Therefore, they exhibit interesting reactivity across all three oxidation states. Due to these fascinating properties, nitroxides find extensive applications in diverse fields such as biochemistry, medicinal chemistry, materials science, and organic synthesis. This review focuses on the versatile applications of nitroxides in organic synthesis. For their use in other important fields, we will refer to several review articles. The introductory part provides a brief overview of the history of nitroxide chemistry. Subsequently, the key methods for preparing nitroxides are discussed, followed by an examination of their structural diversity and physical properties. The main portion of this review is dedicated to oxidation reactions, wherein parent nitroxides or their corresponding oxoammonium salts serve as active species. It will be demonstrated that various functional groups (such as alcohols, amines, enolates, and alkanes among others) can be efficiently oxidized. These oxidations can be carried out using nitroxides as catalysts in combination with various stoichiometric terminal oxidants. By reducing nitroxides to their corresponding anions, they become effective reducing reagents with intriguing applications in organic synthesis. Nitroxides possess the ability to selectively react with transient radicals, making them useful for terminating radical cascade reactions by forming alkoxyamines. Depending on their structure, alkoxyamines exhibit weak C-O bonds, allowing for the thermal generation of C radicals through reversible C-O bond cleavage. Such thermally generated C radicals can participate in various radical transformations, as discussed toward the end of this review. Furthermore, the application of this strategy in natural product synthesis will be presented.
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Affiliation(s)
- Dirk Leifert
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
| | - Armido Studer
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
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5
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van der Zee LJ, Pahar S, Richards E, Melen RL, Slootweg JC. Insights into Single-Electron-Transfer Processes in Frustrated Lewis Pair Chemistry and Related Donor-Acceptor Systems in Main Group Chemistry. Chem Rev 2023; 123:9653-9675. [PMID: 37431868 PMCID: PMC10416219 DOI: 10.1021/acs.chemrev.3c00217] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Indexed: 07/12/2023]
Abstract
The activation and utilization of substrates mediated by Frustrated Lewis Pairs (FLPs) was initially believed to occur solely via a two-electron, cooperative mechanism. More recently, the occurrence of a single-electron transfer (SET) from the Lewis base to the Lewis acid was observed, indicating that mechanisms that proceed via one-electron-transfer processes are also feasible. As such, SET in FLP systems leads to the formation of radical ion pairs, which have recently been more frequently observed. In this review, we aim to discuss the seminal findings regarding the recently established insights into the SET processes in FLP chemistry as well as highlight examples of this radical formation process. In addition, applications of reported main group radicals will also be reviewed and discussed in the context of the understanding of SET processes in FLP systems.
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Affiliation(s)
- Lars J.
C. van der Zee
- Van
’t Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands
| | - Sanjukta Pahar
- Cardiff
Catalysis Institute, Cardiff University, Translational Research Hub, Maindy
Road, Cathays, Cardiff, CF24 4HQ Wales, United Kingdom
| | - Emma Richards
- Cardiff
Catalysis Institute, Cardiff University, Translational Research Hub, Maindy
Road, Cathays, Cardiff, CF24 4HQ Wales, United Kingdom
| | - Rebecca L. Melen
- Cardiff
Catalysis Institute, Cardiff University, Translational Research Hub, Maindy
Road, Cathays, Cardiff, CF24 4HQ Wales, United Kingdom
| | - J. Chris Slootweg
- Van
’t Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands
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6
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Dolai R, Kumar R, Elvers BJ, Pal PK, Joseph B, Sikari R, Nayak MK, Maiti A, Singh T, Chrysochos N, Jayaraman A, Krummenacher I, Mondal J, Priyakumar UD, Braunschweig H, Yildiz CB, Schulzke C, Jana A. Carbodicarbenes and Striking Redox Transitions of their Conjugate Acids: Influence of NHC versus CAAC as Donor Substituents. Chemistry 2023; 29:e202202888. [PMID: 36129127 PMCID: PMC10100033 DOI: 10.1002/chem.202202888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Indexed: 01/11/2023]
Abstract
Herein, a new type of carbodicarbene (CDC) comprising two different classes of carbenes is reported; NHC and CAAC as donor substituents and compare the molecular structure and coordination to Au(I)Cl to those of NHC-only and CAAC-only analogues. The conjugate acids of these three CDCs exhibit notable redox properties. Their reactions with [NO][SbF6 ] were investigated. The reduction of the conjugate acid of CAAC-only based CDC with KC8 results in the formation of hydrogen abstracted/eliminated products, which proceed through a neutral radical intermediate, detected by EPR spectroscopy. In contrast, the reduction of conjugate acids of NHC-only and NHC/CAAC based CDCs led to intermolecular reductive (reversible) carbon-carbon sigma bond formation. The resulting relatively elongated carbon-carbon sigma bonds were found to be readily oxidized. They were, thus, demonstrated to be potent reducing agents, underlining their potential utility as organic electron donors and n-dopants in organic semiconductor molecules.
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Affiliation(s)
- Ramapada Dolai
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
| | - Rahul Kumar
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
| | - Benedict J Elvers
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17489, Greifswald, Germany
| | - Pradeep Kumar Pal
- International Institute of Information Technology Gachibowli, Hyderabad, 500032, India
| | - Benson Joseph
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
| | - Rina Sikari
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
| | - Mithilesh Kumar Nayak
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
| | - Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
| | - Tejender Singh
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
| | - Nicolas Chrysochos
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
| | - Arumugam Jayaraman
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Jagannath Mondal
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
| | - U Deva Priyakumar
- International Institute of Information Technology Gachibowli, Hyderabad, 500032, India
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Cem B Yildiz
- Department of Aromatic and Medicinal Plants, Aksaray University, Aksaray, 68100, Turkey
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17489, Greifswald, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad Gopanpally, Hyderabad, 500046, Telangana, India
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8
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Chen C, Daniliuc CG, Klabunde S, Hansen MR, Kehr G, Erker G. Generation of Boryl-nitroxide Radicals from a Boraalkene via the Nitroso Ene Reaction. Chem Sci 2022; 13:10891-10896. [PMID: 36320693 PMCID: PMC9491209 DOI: 10.1039/d2sc02485c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 08/09/2022] [Indexed: 11/21/2022] Open
Abstract
Examples of isolated boron substituted nitroxide radicals are rare. The reaction of the reactive cyclic boraalkene 3 with nitrosobenzene yields a mixture of the [2 + 2] cycloaddition product 4a, the B-nitroxide radicals 5a and 6a and the azoxybenzene co-product 7avia a bora nitroso ene reaction pathway, the boron analogue of the nitroso ene reaction. The products were separated by flash chromatography, and the B-nitroxide radicals were characterized by X-ray diffraction and EPR spectroscopy. Radical 5a was shown to be a hydrogen atom abstractor. Both the B-nitroxide radicals are more easily oxidized compared to e.g. TEMPO, as shown by cyclic voltammetry. The NHC-stabilized boraalkene reacts with nitrosobenzene to give a [2+2] cycloaddition product plus a pair of persistent borylnitroxide radicals. These are thought to be formed by means of a bora nitroso ene reaction followed by H-atom transfer.![]()
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Affiliation(s)
- Chaohuang Chen
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Sina Klabunde
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster Corrensstraße 28/3040 48149 Münster Germany
| | - Michael Ryan Hansen
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster Corrensstraße 28/3040 48149 Münster Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Gerhard Erker
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
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9
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Liu X, Wang X, Li Y, Yu T, Zhao W, Liu L. On the association of frustrated Lewis pairs in ionic liquids: a molecular dynamics simulation study. Phys Chem Chem Phys 2021; 23:12541-12548. [PMID: 33998614 DOI: 10.1039/d1cp00479d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Sterically hindered frustrated Lewis pairs (FLPs) have the ability to activate hydrogen molecules, and their reactivity is strongly determined by the geometric parameters of the Lewis acids and bases. A recent experimental study showed that ionic liquids (ILs) could largely improve the effective configuration of FLPs. However, the detailed mechanistic profile is still unclear. Herein, we performed molecular dynamics (MD) simulations to reveal the effects of ILs on the structures of FLPs, in particular, the association of Lewis acids and bases. For this purpose, mixed systems were adopted consisting of the ILs [Cnmim][NTf2] (n = 6, 10, 14), [C6mim][PF6] and [C6mim][CTf3] and the typical FLP (tBu)3P/B(C6F5)3 for MD simulations. Radial distribution functions (RDFs) results show that toluene competes with (tBu)3P to interact with B(C6F5)3, resulting in a relatively low effective (tBu)3P/B(C6F5)3 complex, while [C10mim][NTf2] shows less competition with (tBu)3P, which increases the amount of effective FLPs. Spatial distribution functions (SDFs) results show that toluene forms a continuum solvation-shell, which hinders the interactions between (tBu)3P and B(C6F5)3, while [C10mim][NTf2] leaves relatively large empty spaces, which are accessible for (tBu)3P or B(C6F5)3 molecules, resulting in higher probabilities of effective FLP structures. Lastly, we find that the longer alkyl chain length of [Cnmim]+ cations, the higher the amount of effective (tBu)3P/B(C6F5)3 pairs, and the anion [CTf3]- shows negative effects, for which even less effective (tBu)3P/B(C6F5)3 pairs have been found compared to those of toluene.
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Affiliation(s)
- Xiaoqing Liu
- School of Environment and Safety Engineering, North University of China, Taiyuan, 030051, P. R. China.
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10
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Sharma G, Newman PD, Platts JA. A review of quantum chemical studies of Frustrated Lewis Pairs. J Mol Graph Model 2021; 105:107846. [DOI: 10.1016/j.jmgm.2021.107846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/13/2021] [Accepted: 01/20/2021] [Indexed: 11/16/2022]
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11
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Zhang C, Wang J, Su W, Lin Z, Ye Q. Synthesis, Characterization, and Density Functional Theory Studies of Three-Dimensional Inorganic Analogues of 9,10-Diboraanthracene-A New Class of Lewis Superacids. J Am Chem Soc 2021; 143:8552-8558. [PMID: 33984238 DOI: 10.1021/jacs.1c03057] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The three-dimensional inorganic analogues of 9,10-diboraanthracene, B2X2(C2B10H10)2 (X = Cl, 1; X = Br, 2), were attained by salt elimination of Li2C2B10H10 and trihaloboranes. The methyl- and phenyl-substituted compounds B2Me2(C2B10H10)2 (3) and B2Ph2(C2B10H10)2 (4) were obtained by treating 1 or 2 with the corresponding Grignard reagents. These compounds were fully characterized by NMR, cyclic voltammetry (CV), IR, and single-crystal X-ray diffraction analyses. Experimental (CV and Gutmann-Beckett method) and computational (fluoride ion affinity, hydride ion affinity and LUMO energy) results suggest that the order of Lewis acidity is 2 > 1 > 4 > 3 > SbF5. Treatment of 1 or 2 with HSiEt3 gave a rare neutral borane-silane adduct, (Et3SiH)2B2H2(C2B10H10)2 (5). The equilibrium of 5 in solution was thoroughly investigated by spectroscopy and quantum calculations.
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Affiliation(s)
- Chonghe Zhang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Junyi Wang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China.,Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Wei Su
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Zhenyang Lin
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Qing Ye
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
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12
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Koike T, Kosai T, Iwamoto T. Intermolecular C-H Activation at the Allylic/Benzylic and Homoallylic/Homobenzylic Positions of Cyclic Hydrocarbons by a Stable Divalent Silicon Species. Chemistry 2021; 27:724-734. [PMID: 32931054 DOI: 10.1002/chem.202003541] [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: 07/29/2020] [Revised: 08/26/2020] [Indexed: 11/11/2022]
Abstract
Direct activation of inert C(sp3 )-H bonds by main group element species is yet a formidable challenge. Herein, the dehydrogenation of cyclohexene and 1,2,3,4-tetrahydronaphthalene through the allylic/benzylic and homoallylic/homobenzylic C-H bond activation by cyclic (alkyl)(amino)silylene 1 in neat conditions is reported to yield the corresponding aromatic compounds. As for the reaction of cyclohexene, allylsilane 3 and 7-silanorbornene 4 were also observed, which could be interpreted as a direct dehydrogenative silylation reaction of monoalkenes at the allylic positions. Experimental and computational studies suggest that the dehydrogenation of cyclohexene at the homoallylic position was accomplished by a combination of silylene 1 and radical intermediates such as hydrosilyl radical INT1 or cyclohexenyl radical H, which are generated in the initial step of the reaction.
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Affiliation(s)
- Taichi Koike
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan
| | - Tomoyuki Kosai
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan
| | - Takeaki Iwamoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan
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13
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Dasgupta A, Richards E, Melen RL. Frustrated Radical Pairs: Insights from EPR Spectroscopy. Angew Chem Int Ed Engl 2021; 60:53-65. [PMID: 32931604 PMCID: PMC7883636 DOI: 10.1002/anie.202010633] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Indexed: 12/29/2022]
Abstract
Progress in frustrated Lewis pair (FLP) chemistry has revealed the importance of the main group elements in catalysis, opening new avenues in synthetic chemistry. Recently, new reactivities of frustrated Lewis pairs have been uncovered that disclose that certain combinations of Lewis acids and bases undergo single-electron transfer (SET) processes. Here an electron can be transferred from the Lewis basic donor to a Lewis acidic acceptor to generate a reactive frustrated radical pair (FRP). This minireview aims to showcase the recent advancements in this emerging field covering the synthesis and reactivities of frustrated radical pairs, with extensive highlights of the results from Electron Paramagnetic Resonance (EPR) spectroscopy to explain the nature and stability of the different radical species observed.
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Affiliation(s)
- Ayan Dasgupta
- School of ChemistryCardiff Catalysis InstituteCardiff UniversityMain Building, Park PlaceCardiffCF10 3ATUK
| | - Emma Richards
- School of ChemistryCardiff Catalysis InstituteCardiff UniversityMain Building, Park PlaceCardiffCF10 3ATUK
| | - Rebecca L. Melen
- School of ChemistryCardiff Catalysis InstituteCardiff UniversityMain Building, Park PlaceCardiffCF10 3ATUK
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14
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Sun Q, Daniliuc CG, Kehr G, Erker G. Reaction of carbon oxides with an ethylene-bridged PH/B Lewis pair. Dalton Trans 2021; 50:3523-3528. [PMID: 33599654 DOI: 10.1039/d1dt00459j] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction of 2,4,6-tri(tert-butyl)phenyl vinyl phosphane with Piers' borane [HB(C6F5)2] gave the ethylene-bridged PH/B frustrated Lewis pair (FLP) system. It is a monomer at high temperature (>323 K), but exists as an associated 12-membered macrocyclic trimer below 273 K. The PH/B FLP splits dihydrogen and serves as a metal-free hydrogenation catalyst. It adds carbon dioxide. It serves as a PH/B template for the reduction of carbon monoxide by the HB(C6F5)2 borane to the formyl stage. The resulting six membered P/B/O containing heterocycle is opened upon treatment with pyridine and it reacts with benzaldehyde in a boron mediated Claisen-Tishchenko reaction.
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Affiliation(s)
- Qiu Sun
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany.
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany.
| | - Gerald Kehr
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany.
| | - Gerhard Erker
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany.
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15
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Zhang J, Xie Z. Tri-insertion with dearomatization of terminal arylalkynes using a carborane based frustrated Lewis pair template. Chem Sci 2020; 12:1745-1749. [PMID: 34163934 PMCID: PMC8179331 DOI: 10.1039/d0sc05755j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 11/27/2020] [Indexed: 01/12/2023] Open
Abstract
Intramolecular vicinal Frustrated Lewis Pairs (FLPs) have played a significant role in the activation of small molecules, and their stabilities and reactivities are found to strongly depend on the nature of the bridging units. This work reports a new carborane based FLP, 1-PPh2-2-BPh2-1,2-C2B10H10 (2), which reacts with an equimolar amount of p-R2NC6H4C[triple bond, length as m-dash]CH (R = Me, Et, Ph) at room temperature to give C[triple bond, length as m-dash]C triple bond addition products 1,2-[PPh2C(R2NC6H4)[double bond, length as m-dash]CHBPh2]-1,2-C2B10H10 (3) in high yields. Compounds 3 react further with two equiv. of p-R2NC6H4C[triple bond, length as m-dash]CH (R = Me, Et) at 60-70 °C to give unprecedented stereoselective tri-insertion products, 3,3a,6,6a-tetrahydronaphtho[1,8a-b]borole tricycles (4), in which one of the aryl rings from arylacetylene moieties has been dearomatized with the formation of four stereocenters including one quaternary carbon center. It is noted that the phosphine unit functions as a catalyst during the reactions. After trapping and structural characterization of a key intermediate, a reaction mechanism is proposed, involving sequential alkyne insertion and 1,2-boryl migration.
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Affiliation(s)
- Jian Zhang
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong Shatin New Territories Hong Kong China
| | - Zuowei Xie
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong Shatin New Territories Hong Kong China
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16
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Dasgupta A, Richards E, Melen RL. Frustrated Radical Pairs: Insights from EPR Spectroscopy. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202010633] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Ayan Dasgupta
- School of Chemistry Cardiff Catalysis Institute Cardiff University Main Building, Park Place Cardiff CF10 3AT UK
| | - Emma Richards
- School of Chemistry Cardiff Catalysis Institute Cardiff University Main Building, Park Place Cardiff CF10 3AT UK
| | - Rebecca L. Melen
- School of Chemistry Cardiff Catalysis Institute Cardiff University Main Building, Park Place Cardiff CF10 3AT UK
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17
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Affiliation(s)
- Nan Li
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University Beijing 100871 China
- Henan Key Laboratory of Function‐Oriented Porous Materials, College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang Henan 471934 China
| | - Wen‐Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University Beijing 100871 China
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18
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Lichtenberg C. Main-Group Metal Complexes in Selective Bond Formations Through Radical Pathways. Chemistry 2020; 26:9674-9687. [PMID: 32048770 PMCID: PMC7496981 DOI: 10.1002/chem.202000194] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/10/2020] [Indexed: 12/21/2022]
Abstract
Recent years have witnessed remarkable advances in radical reactions involving main-group metal complexes. This includes the isolation and detailed characterization of main-group metal radical compounds, but also the generation of highly reactive persistent or transient radical species. A rich arsenal of methods has been established that allows control over and exploitation of their unusual reactivity patterns. Thus, main-group metal compounds have entered the field of selective bond formations in controlled radical reactions. Transformations that used to be the domain of late transition-metal compounds have been realized, and unusual selectivities, high activities, as well as remarkable functional-group tolerances have been reported. Recent findings demonstrate the potential of main-group metal compounds to become standard tools of synthetic chemistry, catalysis, and materials science, when operating through radical pathways.
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Affiliation(s)
- Crispin Lichtenberg
- Institute of Inorganic ChemistryJulius-Maximilians-University WürzburgAm Hubland97074WürzburgGermany
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19
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Andrews RJ, Stephan DW. Isolable Anionic, Neutral and Cationic Radicals from Reactions of N,N'-Dimesityldiamidocarbene and Lewis Acids. Chemistry 2020; 26:7194-7198. [PMID: 32149432 DOI: 10.1002/chem.202001191] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Indexed: 01/04/2023]
Abstract
B(C6 F5 )3 undergoes nucleophilic attack by N,N'-dimesityldiamidocarbene (DAC) with fluoride transfer to the boron center, resulting in a new zwitterion (1). This B-F fluoride can be replaced or abstracted to give the corresponding hydride (2) or triflate (3) derivatives or the corresponding cation (4). These species are reduced with KC8 or Cp2 Co to give isolable anionic and neutral radicals (5-8). Similarly, the [Ph3 C] cation undergoes nucleophilic attack by DAC resulting in the spontaneous formation of the radical cation (9).
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Affiliation(s)
- Ryan J Andrews
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON, M5S 3H4, Canada
| | - Douglas W Stephan
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON, M5S 3H4, Canada
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20
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Li J, Mück-Lichtenfeld C, Daniliuc CG, Kehr G, Erker G. Using the Secondary PH/BH Functional Groups of an Active Geminal Frustrated Lewis Pair for Carbon Monoxide Reduction and Reactions with Nitriles and Isonitriles. Angew Chem Int Ed Engl 2020; 59:12477-12483. [PMID: 31994804 DOI: 10.1002/anie.202000612] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Indexed: 11/10/2022]
Abstract
Reaction of the secondary alkynyl(Mes*)PH phosphane 2 with (Fmes)BH2 ⋅SMe2 gives the geminal PH/BH frustrated Lewis pair (FLP) 3. The PH and the BH functions are jointly used in the reduction of carbon monoxide under mild reaction conditions to give the [P]-CH2 -O-[B] product. A subsequent cycloaddition sequence results in the liberation of formaldehyde. The FLP 3 reacts with benzonitrile to give a P-benzamidine, and it couples two isonitriles at the FLP framework.
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Affiliation(s)
- Jun Li
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Christian Mück-Lichtenfeld
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Gerhard Erker
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany
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21
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Li J, Mück‐Lichtenfeld C, Daniliuc CG, Kehr G, Erker G. Using the Secondary PH/BH Functional Groups of an Active Geminal Frustrated Lewis Pair for Carbon Monoxide Reduction and Reactions with Nitriles and Isonitriles. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000612] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Jun Li
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Christian Mück‐Lichtenfeld
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Constantin G. Daniliuc
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Gerhard Erker
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
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22
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Affiliation(s)
- Wei Meng
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences Beijing 100049 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Xiangqing Feng
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences Beijing 100049 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Haifeng Du
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences Beijing 100049 China
- University of Chinese Academy of Sciences Beijing 100049 China
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23
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Knitsch R, Brinkkötter M, Wiegand T, Kehr G, Erker G, Hansen MR, Eckert H. Solid-State NMR Techniques for the Structural Characterization of Cyclic Aggregates Based on Borane-Phosphane Frustrated Lewis Pairs. Molecules 2020; 25:E1400. [PMID: 32204399 PMCID: PMC7144405 DOI: 10.3390/molecules25061400] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/15/2020] [Accepted: 03/17/2020] [Indexed: 12/17/2022] Open
Abstract
Modern solid-state NMR techniques offer a wide range of opportunities for the structural characterization of frustrated Lewis pairs (FLPs), their aggregates, and the products of cooperative addition reactions at their two Lewis centers. This information is extremely valuable for materials that elude structural characterization by X-ray diffraction because of their nanocrystalline or amorphous character, (pseudo-)polymorphism, or other types of disordering phenomena inherent in the solid state. Aside from simple chemical shift measurements using single-pulse or cross-polarization/magic-angle spinning NMR detection techniques, the availability of advanced multidimensional and double-resonance NMR methods greatly deepened the informational content of these experiments. In particular, methods quantifying the magnetic dipole-dipole interaction strengths and indirect spin-spin interactions prove useful for the measurement of intermolecular association, connectivity, assessment of FLP-ligand distributions, and the stereochemistry of adducts. The present review illustrates several important solid-state NMR methods with some insightful applications to open questions in FLP chemistry, with a particular focus on supramolecular associates.
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Affiliation(s)
- Robert Knitsch
- Institut für Physikalische Chemie, WWU Münster, 48149 Münster, Germany; (R.K.); (M.B.); (M.R.H.)
| | - Melanie Brinkkötter
- Institut für Physikalische Chemie, WWU Münster, 48149 Münster, Germany; (R.K.); (M.B.); (M.R.H.)
| | - Thomas Wiegand
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland;
| | - Gerald Kehr
- Organisch-Chemisches Institut, WWU Münster, 48149 Münster, Germany; (G.K.); (G.E.)
| | - Gerhard Erker
- Organisch-Chemisches Institut, WWU Münster, 48149 Münster, Germany; (G.K.); (G.E.)
| | - Michael Ryan Hansen
- Institut für Physikalische Chemie, WWU Münster, 48149 Münster, Germany; (R.K.); (M.B.); (M.R.H.)
| | - Hellmut Eckert
- Institut für Physikalische Chemie, WWU Münster, 48149 Münster, Germany; (R.K.); (M.B.); (M.R.H.)
- Instituto de Física de Sao Carlos, Universidad de Sao Paulo, Sao Carlos SP 13566-590, Brazil
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24
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Hong M, Wu S, Li J, Wang J, Wei L, Li K. Aerobic oxidation of 5-(hydroxymethyl)furfural into 2,5-diformylfuran catalyzed by starch supported aluminum nitrate. CATAL COMMUN 2020. [DOI: 10.1016/j.catcom.2019.105909] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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25
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Jie X, Sun Q, Daniliuc CG, Knitsch R, Hansen MR, Eckert H, Kehr G, Erker G. Cycloaddition Reactions of an Active Cyclic Phosphane/Borane Pair with Alkenes, Alkynes, and Carbon Dioxide. Chemistry 2020; 26:1269-1273. [DOI: 10.1002/chem.201905171] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Indexed: 11/05/2022]
Affiliation(s)
- Xiaoming Jie
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Qiu Sun
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Constantin G. Daniliuc
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Robert Knitsch
- Institut für Physikalische ChemieWestfälische Wilhelms-Universität, Münster Corrensstraße 28 48149 Münster Germany
| | - Michael Ryan Hansen
- Institut für Physikalische ChemieWestfälische Wilhelms-Universität, Münster Corrensstraße 28 48149 Münster Germany
| | - Hellmut Eckert
- Institut für Physikalische ChemieWestfälische Wilhelms-Universität, Münster Corrensstraße 28 48149 Münster Germany
- Instituto de Fisica, Sáo CarlosUniversidade de São Paulo CP 369 13566-590 São Carlos S. P. Brazil
| | - Gerald Kehr
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Gerhard Erker
- Organisch-Chemisches InstitutWestfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
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26
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Cao LL, Zhou J, Qu Z, Stephan DW. Single Electron Transfer to Diazomethane-Borane Adducts Prompts C-H Bond Activations. Angew Chem Int Ed Engl 2019; 58:18487-18491. [PMID: 31589360 PMCID: PMC6972512 DOI: 10.1002/anie.201912338] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Indexed: 12/31/2022]
Abstract
While (Ph2 CN2 )B(C6 F5 )3 is unstable, single electron transfer from Cp*2 Co affords the isolation of stable products [Cp*2 Co][Ph2 CNNHB(C6 F5 )3 ] 1 and [Cp*Co(C5 Me4 CH2 B(C6 F5 )3 )] 2. The analogous combination of Ph2 CN2 and BPh3 showed no evidence of adduct formation and yet single electron transfer from Cp*2 Cr affords the species [Cp*2 Cr][PhC(C6 H4 )NNBPh3 ] 3 and [Cp*2 Cr][Ph2 CNNHBPh3 ] 4. Computations showed both reactions proceed via transient radical anions of the diphenyldiazomethane-borane adducts to effect C-H bond activations.
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Affiliation(s)
- Levy L. Cao
- Department of ChemistryUniversity of Toronto80 St. George St.TorontoOntarioM5S3H6Canada
| | - Jiliang Zhou
- Department of ChemistryUniversity of Toronto80 St. George St.TorontoOntarioM5S3H6Canada
| | - Zheng‐Wang Qu
- Mulliken Center for Theoretical ChemistryInstitut für Physikalische und Theoretische ChemieRheinische Friedrich-Wilhelms-Universität BonnBeringstrasse 453115BonnGermany
| | - Douglas W. Stephan
- Department of ChemistryUniversity of Toronto80 St. George St.TorontoOntarioM5S3H6Canada
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27
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Cao LL, Zhou J, Qu Z, Stephan DW. Single Electron Transfer to Diazomethane–Borane Adducts Prompts C−H Bond Activations. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201912338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Levy L. Cao
- Department of ChemistryUniversity of Toronto 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Jiliang Zhou
- Department of ChemistryUniversity of Toronto 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Zheng‐Wang Qu
- Mulliken Center for Theoretical ChemistryInstitut für Physikalische und Theoretische ChemieRheinische Friedrich-Wilhelms-Universität Bonn Beringstrasse 4 53115 Bonn Germany
| | - Douglas W. Stephan
- Department of ChemistryUniversity of Toronto 80 St. George St. Toronto Ontario M5S3H6 Canada
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28
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Kim Y, Bielawski CW, Lee E. Oxygen atom transfer: a mild and efficient method for generating iminyl radicals. Chem Commun (Camb) 2019; 55:7061-7064. [PMID: 31143894 DOI: 10.1039/c9cc03521d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Treating iminoxyl species with oxygen acceptors such as PPh3 resulted in oxygen atom transfer and afforded the corresponding iminyl radicals. DFT and other calculations revealed that association between the oxygen atom acceptors and the iminoxyl species results in the formation of key intermediates during the reaction. Subsequent dissociation is accompanied with homolytic cleavage of the N-O bond and generates iminyl radicals with spin densities that are localized on exocyclic nitrogen atoms.
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Affiliation(s)
- Youngsuk Kim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea. and Center for Self-assembly and Complexity (CSC), Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea
| | - Christopher W Bielawski
- Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS), Ulsan, 44919, Republic of Korea and Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea and Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Eunsung Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea. and Center for Self-assembly and Complexity (CSC), Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea and Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
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29
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Hong M, Min J, Wu S, Cui H, Zhao Y, Li J, Wang S. Metal Nitrate Catalysis for Selective Oxidation of 5-Hydroxymethylfurfural into 2,5-Diformylfuran under Oxygen Atmosphere. ACS OMEGA 2019; 4:7054-7060. [PMID: 31459816 PMCID: PMC6648045 DOI: 10.1021/acsomega.9b00391] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/11/2019] [Indexed: 05/26/2023]
Abstract
Selective synthesis of various versatile compounds from biomass is of great importance to displace traditional fossil fuel resources. Here, homogeneous metal nitrate (M(NO3) x )/(2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) and M(NO3) x /TEMPO/NaNO2 catalyst systems in glacial acetic acid and acetonitrile, respectively, have been found to be highly active and practically sustainable for selective oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF) using pure O2 or even O2 in air as the oxidant. The catalytic methods enable full HMF conversion with a nearly 100% DFF selectivity at 50 °C under atmospheric pressure using a very simple reaction setup and workup. Mechanistic aspects are discussed. The influences of reaction conditions such as different metal catalysts, catalyst loading, solvents, and reaction temperature on the promotion effect were studied. Meanwhile, the catalyst systems had also good performance for aerobic oxidation of other alcohols.
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Affiliation(s)
- Mei Hong
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization
of Forest Resources and College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People’s Republic of China
| | - Jie Min
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization
of Forest Resources and College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People’s Republic of China
| | - Shuangyan Wu
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization
of Forest Resources and College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People’s Republic of China
| | - Huangui Cui
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization
of Forest Resources and College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People’s Republic of China
| | - Yuxin Zhao
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization
of Forest Resources and College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People’s Republic of China
| | - Jiatong Li
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization
of Forest Resources and College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People’s Republic of China
| | - Shifa Wang
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization
of Forest Resources and College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People’s Republic of China
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30
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Kinder TA, Pior R, Blomeyer S, Neumann B, Stammler H, Mitzel NW. A Neutral Germanium/Phosphorus Frustrated Lewis Pair and Its Contrasting Reactivity Compared to Its Silicon Analogue. Chemistry 2019; 25:5899-5903. [PMID: 30843630 DOI: 10.1002/chem.201901068] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Indexed: 11/06/2022]
Affiliation(s)
- Timo A. Kinder
- Lehrstuhl für Anorganische Chemie und Strukturchemie und Centrum für, Molekulare Materialien CM2Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - René Pior
- Lehrstuhl für Anorganische Chemie und Strukturchemie und Centrum für, Molekulare Materialien CM2Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Sebastian Blomeyer
- Lehrstuhl für Anorganische Chemie und Strukturchemie und Centrum für, Molekulare Materialien CM2Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Beate Neumann
- Lehrstuhl für Anorganische Chemie und Strukturchemie und Centrum für, Molekulare Materialien CM2Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Hans‐Georg Stammler
- Lehrstuhl für Anorganische Chemie und Strukturchemie und Centrum für, Molekulare Materialien CM2Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Norbert W. Mitzel
- Lehrstuhl für Anorganische Chemie und Strukturchemie und Centrum für, Molekulare Materialien CM2Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
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31
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Abstract
While conventional approaches to stabilizing main group radicals have involved the use of Lewis acids or bases, this tutorial review focuses on new avenues to main group radicals derived from combinations of donor and acceptor molecules.
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Affiliation(s)
- Liu Leo Liu
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
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32
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Krachko T, Nicolas E, Ehlers AW, Nieger M, Slootweg JC. Ring-opening of Epoxides Mediated by Frustrated Lewis Pairs. Chemistry 2018; 24:12669-12677. [DOI: 10.1002/chem.201801909] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 06/06/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Tetiana Krachko
- Van 't Hoff Institute for Molecular Sciences; University of Amsterdam; Science Park 904, P.O. Box 94157 1090 GD Amsterdam The Netherlands
| | - Emmanuel Nicolas
- Van 't Hoff Institute for Molecular Sciences; University of Amsterdam; Science Park 904, P.O. Box 94157 1090 GD Amsterdam The Netherlands
- Current address: NIMBE, CEA, CNRS; Université Paris-Saclay, CEA Saclay; 91191 Gif sur Yvette Cedex France
| | - Andreas W. Ehlers
- Van 't Hoff Institute for Molecular Sciences; University of Amsterdam; Science Park 904, P.O. Box 94157 1090 GD Amsterdam The Netherlands
- Department of Chemistry, Science Faculty; University of Johannesburg; P.O. Box 254 Auckland Park Johannesburg South Africa
| | - Martin Nieger
- Department of Chemistry; University of Helsinki; A. I. Virtasen aukio 1, P.O. Box 55 Helsinki Finland
| | - J. Chris Slootweg
- Van 't Hoff Institute for Molecular Sciences; University of Amsterdam; Science Park 904, P.O. Box 94157 1090 GD Amsterdam The Netherlands
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33
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Wang L, Kehr G, Daniliuc CG, Brinkkötter M, Wiegand T, Wübker AL, Eckert H, Liu L, Brandenburg JG, Grimme S, Erker G. Solid state frustrated Lewis pair chemistry. Chem Sci 2018; 9:4859-4865. [PMID: 29910938 PMCID: PMC5982199 DOI: 10.1039/c8sc01089g] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/20/2018] [Indexed: 11/29/2022] Open
Abstract
In solution the PCy3/B(C6F5)3 pair is rapidly deactivated by nucleophilic aromatic substitution. In the solid state deactivation is effectively suppressed and the active frustrated phosphane/borane Lewis pair splits dihydrogen or adds to sulfur dioxide. A variety of phosphane/B(C6F5)3 pairs have been used to carry out active FLP reactions in the solid state. The reactions were analyzed by DFT calculations and by solid state NMR spectroscopy. The solid state dihydrogen splitting reaction was also carried out under near to ambient conditions with suspensions of the non-quenched phosphane/borane mixtures in the fluorous liquid perfluoromethylcyclohexane.
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Affiliation(s)
- Long Wang
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany .
| | - Gerald Kehr
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany .
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany .
| | - Melanie Brinkkötter
- Institut für Physikalische Chemie , Graduate School of Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 30 , 48149 Münster , Germany .
| | - Thomas Wiegand
- Laboratorium für Physikalische Chemie , ETH Zürich , Vladimir-Prelog-Weg 2 , 8093 Zürich , Switzerland
| | - Anna-Lena Wübker
- Institut für Physikalische Chemie , Graduate School of Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 30 , 48149 Münster , Germany .
| | - Hellmut Eckert
- Institut für Physikalische Chemie , Graduate School of Chemistry , Westfälische Wilhelms-Universität Münster , Corrensstraße 30 , 48149 Münster , Germany .
- Institute of Physics in Sao Carlos , University of Sao Paulo , CEP 369 , Sao Carlos SP 13566-590 , Brazil
| | - Lei Liu
- Mulliken Center for Theoretical Chemistry , Institut für Physikalische und Theoretische Chemie , Universität Bonn , Beringstraße 4 , 53115 Bonn , Germany .
| | - Jan Gerit Brandenburg
- London Centre for Nanotechnology , University College London , 17-19 Gordon Street , London , WC1H 0AH , UK
- Mulliken Center for Theoretical Chemistry , Institut für Physikalische und Theoretische Chemie , Universität Bonn , Beringstraße 4 , 53115 Bonn , Germany .
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry , Institut für Physikalische und Theoretische Chemie , Universität Bonn , Beringstraße 4 , 53115 Bonn , Germany .
| | - Gerhard Erker
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany .
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34
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Liu LL, Cao LL, Zhu D, Zhou J, Stephan DW. Homolytic cleavage of peroxide bonds via a single electron transfer of a frustrated Lewis pair. Chem Commun (Camb) 2018; 54:7431-7434. [PMID: 29781011 DOI: 10.1039/c8cc03522a] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Single electron transfer (SET) reactions are effected by the combination of a Mes3P/B(C6F5)3 frustrated Lewis pair with benzoyl peroxide derivatives. The resulting homolytic cleavage of the peroxide bonds affords the radical salts [Mes3P˙]+[RCOOB(C6F5)3]- (R = Ph 1, p-BrC6H42, p-MeC6H43). These species react with Ph3SnH to give [Mes3PH]+[RCOOB(C6F5)3]- (R = Ph 10, p-BrC6H411, p-MeC6H412) and (Ph3Sn)2. The mechanism of these SET reactions is discussed in light of control experiments and DFT calculations.
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Affiliation(s)
- Liu Leo Liu
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada.
| | - Levy L Cao
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada.
| | - Diya Zhu
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada.
| | - Jiliang Zhou
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada.
| | - Douglas W Stephan
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada.
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35
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Nie Y, Zhi X, Du H, Yang J. Zn(OAc)₂-Catalyzing Ring-Opening Polymerization of N-Carboxyanhydrides for the Synthesis of Well-Defined Polypeptides. Molecules 2018; 23:E760. [PMID: 29587473 PMCID: PMC6017970 DOI: 10.3390/molecules23040760] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 03/23/2018] [Accepted: 03/23/2018] [Indexed: 11/16/2022] Open
Abstract
Despite notable progress, the fabrication of well-defined polypeptides via controlled ring-opening polymerization (ROP) of α-amino acid N-carboxyanhydrides (NCAs) using convenient catalysts under mild conditions in a relatively short polymerization time is still challenging. Herein, an easily obtained catalyst system composed of zinc acetate and aniline was explored to mediate the fast ROP of γ-benzyl-l-glutamate-N-carboxyanhydride (BLG-NCA) monomer, to produce poly(γ-benzyl-l-glutamates) (PBLGs) with controllable molecular weights and narrow dispersity. Considering the excellent cooperative action of zinc acetate and a broad scope of aniline derivatives with different functional groups to control ROP of BLG-NCA, this method may offer a useful platform enabling the rapid generation of end-functionalized PBLG and block copolymers for numerous biomedical applications.
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Affiliation(s)
- Yanzhao Nie
- State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Xinmei Zhi
- State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Haifeng Du
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Jing Yang
- State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
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36
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Zhang H, Nie Y, Zhi X, Du H, Yang J. Controlled ring-opening polymerization of α-amino acid N-carboxy-anhydride by frustrated amine/borane Lewis pairs. Chem Commun (Camb) 2018; 53:5155-5158. [PMID: 28439585 DOI: 10.1039/c7cc01440f] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In this communication, we presented a novel strategy to control the ROP of α-amino acid N-carboxy-anhydrides using the concept of frustrated Lewis pairs (FLPs). An FLP intermediate containing an interaction between the bulky borane Lewis acid and the amine groups of the propagation chain end is essential to accomplish the polypeptide synthesis with well-defined structures under mild conditions.
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Affiliation(s)
- Hongyuan Zhang
- State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
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37
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Wang L, Dong S, Daniliuc CG, Liu L, Grimme S, Knitsch R, Eckert H, Hansen MR, Kehr G, Erker G. Formation of macrocyclic ring systems by carbonylation of trifunctional P/B/B frustrated Lewis pairs. Chem Sci 2018; 9:1544-1550. [PMID: 29675199 PMCID: PMC5890323 DOI: 10.1039/c7sc04394e] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 12/13/2017] [Indexed: 12/26/2022] Open
Abstract
The trifunctional P/B/B frustrated Lewis pairs 11a-c featuring bulky aryl groups at phosphorus [Dmesp (a), Tipp (b), Mes* (c)] react with H2 by heterolytic hydrogen splitting followed by cleavage of HB(C6F5)2 to give the zwitterionic six-membered heterocyclic PH phosphonium/borate products 14a-c. Compounds 11a,b react with carbon monoxide by means of a Lewis acid induced CO insertion/rearrangement sequence that eventually results in the formation of the macrocyclic dimers 17a,b. The respective carbonylation reaction of the Mes*P/B/B FLP gives the macrocyclic trimer 18c. The new products were characterized spectroscopically and by X-ray diffraction and the reaction mechanism was analyzed by DFT calculations.
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Affiliation(s)
- Long Wang
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstr. 40 , 48149 Münster , Germany .
| | - Shunxi Dong
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstr. 40 , 48149 Münster , Germany .
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstr. 40 , 48149 Münster , Germany .
| | - Lei Liu
- Mulliken Center for Theoretical Chemistry , Institut für Physikalische und Theoretische Chemie , Universität Bonn , Beringstr. 4 , 53115 Bonn , Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry , Institut für Physikalische und Theoretische Chemie , Universität Bonn , Beringstr. 4 , 53115 Bonn , Germany
| | - Robert Knitsch
- Institut für Physikalische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstr. 28/30 , 48149 Münster , Germany
| | - Hellmut Eckert
- Institut für Physikalische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstr. 28/30 , 48149 Münster , Germany
- Institute of Physics in Sao Carlos , University of Sao Paulo , CEP 369 , Sao Carlos , SP 13566-590 , Brazil
| | - Michael Ryan Hansen
- Institut für Physikalische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstr. 28/30 , 48149 Münster , Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstr. 40 , 48149 Münster , Germany .
| | - Gerhard Erker
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstr. 40 , 48149 Münster , Germany .
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38
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Hou L, Liang Y, Wang Q, Zhang Y, Dong D, Zhang N. Lewis Pair-Mediated Surface-Initiated Polymerization. ACS Macro Lett 2018; 7:65-69. [PMID: 35610918 DOI: 10.1021/acsmacrolett.7b00903] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present the first example of surface-initiated polymerization mediated by Lewis pairs for the synthesis of polymer brushes on planar substrates. The method enables the rapid grafting polymerization from the self-assembled monolayer or surface-attached macroinitiators, furnishing linear polymer brushes and bottle-brush brushes. Both homopolyester and block copolyester brushes can be synthesized via this versatile approach. This work not only opens up new opportunities for the application of Lewis pair-mediated polymerization but also enriches the surface-initiated polymerization on different surfaces.
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Affiliation(s)
- Liman Hou
- Key
Laboratory of Synthetic Rubber, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of the Chinese Academy of Sciences, Beijing 100864, China
| | - Yongjiu Liang
- Key
Laboratory of Synthetic Rubber, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Qianyi Wang
- State
Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, China
| | - Yuetao Zhang
- State
Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, China
| | - Dewen Dong
- Key
Laboratory of Synthetic Rubber, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Ning Zhang
- Key
Laboratory of Synthetic Rubber, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
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39
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Nie Y, Wang P, Du H, Meng W, Yang J. An efficient strategy for achieving controlled ring-opening polymerization of O-carboxyanhydrides via amine initiation in collaboration with metal-alkoxide catalysis. Polym Chem 2018. [DOI: 10.1039/c8py01090k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Amines and Zn(C6F5)2 for polymerization initiation and functionality transfer from Zn(C6F5)2 to a metal-alkoxide species for promoting chain propagation to achieve well controlled ring-opening polymerization of O-carboxyanhydrides.
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Affiliation(s)
- Yanzhao Nie
- State Key Laboratory of Chemical Resource Engineering
- Beijing Key Laboratory of Bioprocess
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing 100029
| | - Pei Wang
- State Key Laboratory of Chemical Resource Engineering
- Beijing Key Laboratory of Bioprocess
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing 100029
| | - Haifeng Du
- Beijing National Laboratory for Molecular Sciences
- CAS Key Laboratory of Molecular Recognition and Function
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
| | - Wei Meng
- Beijing National Laboratory for Molecular Sciences
- CAS Key Laboratory of Molecular Recognition and Function
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
| | - Jing Yang
- State Key Laboratory of Chemical Resource Engineering
- Beijing Key Laboratory of Bioprocess
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing 100029
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40
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Schneider C, LaFortune JHW, Melen RL, Stephan DW. Lewis and Brønsted basicity of phosphine-diazomethane derivatives. Dalton Trans 2018; 47:12742-12749. [DOI: 10.1039/c8dt02420k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The compounds EtOC(O)CHNN(PR3) (R = Ph 1, Cy 2, tBu 3) were prepared via the reactions of the diazomethane and a phosphine and their reactivity has been explored.
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41
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Szkop KM, Zhu D, Longobardi LE, Heck J, Stephan DW. Interception of intermediates in phosphine oxidation by mesityl nitrile-N-oxide using frustrated Lewis pairs. Dalton Trans 2018; 47:8933-8939. [DOI: 10.1039/c8dt01717d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
While phosphine oxidation by MesCNO is rapid, FLPs can be used to intercept 1,3-addition intermediates. These species react with tBuOK or [Bu4N]F permitting the oxidation to proceed.
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Affiliation(s)
- Kevin M. Szkop
- Department of Chemistry
- University of Toronto
- Toronto
- Canada M5S 3H6
| | - Diya Zhu
- Department of Chemistry
- University of Toronto
- Toronto
- Canada M5S 3H6
| | | | - Julian Heck
- Department of Chemistry
- University of Toronto
- Toronto
- Canada M5S 3H6
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42
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Perrin FG, Bobbink FD, Păunescu E, Fei Z, Scopelliti R, Laurenczy G, Katsyuba S, Dyson PJ. Towards a frustrated Lewis pair-ionic liquid system. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.07.045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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43
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Kim Y, Lee E. An air-stable N-heterocyclic carbene iminoxyl borate radical zwitterion. Chem Commun (Camb) 2018; 54:6824-6827. [DOI: 10.1039/c8cc01399c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The presented N-heterocyclic carbene iminoxyl borate radical zwitterion shows remarkable stability toward air, moisture, and silica gel.
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Affiliation(s)
- Youngsuk Kim
- Center for Self–assembly and Complexity
- Institute for Basic Science (IBS)
- Pohang
- Republic of Korea
- Department of Chemistry
| | - Eunsung Lee
- Center for Self–assembly and Complexity
- Institute for Basic Science (IBS)
- Pohang
- Republic of Korea
- Department of Chemistry
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44
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Jiang B, Zhang Q, Dang L. Theoretical studies on bridged frustrated Lewis pair (FLP) mediated H2 activation and CO2 hydrogenation. Org Chem Front 2018. [DOI: 10.1039/c8qo00192h] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DFT calculations show that H2 and CO2 activation by bridged phosphane/borane frustrated Lewis pairs (FLPs) experiences a one-step concerted mechanism with small reaction barriers.
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Affiliation(s)
- Beilei Jiang
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province
- Shantou University
- P. R. China
- Department of Chemistry
- Southern University of Science and Technology
| | - Qi Zhang
- Department of Chemistry
- Southern University of Science and Technology
- Guangdong
- P. R. China
| | - Li Dang
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province
- Shantou University
- P. R. China
- Department of Chemistry
- Southern University of Science and Technology
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45
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Tang C, Liang Q, Jupp AR, Johnstone TC, Neu RC, Song D, Grimme S, Stephan DW. 1,1-Hydroboration and a Borane Adduct of Diphenyldiazomethane: A Potential Prelude to FLP-N2
Chemistry. Angew Chem Int Ed Engl 2017; 56:16588-16592. [DOI: 10.1002/anie.201710337] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 10/31/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Connie Tang
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Quiming Liang
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Andrew R. Jupp
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Timothy C. Johnstone
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Rebecca C. Neu
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Datong Song
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry; Institut fuer Physikalische und Theoretische Chemie; Universitaet Bonn; Beringstrasse 4 53115 Bonn Germany
| | - Douglas W. Stephan
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
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46
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Tang C, Liang Q, Jupp AR, Johnstone TC, Neu RC, Song D, Grimme S, Stephan DW. 1,1-Hydroboration and a Borane Adduct of Diphenyldiazomethane: A Potential Prelude to FLP-N2
Chemistry. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201710337] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Connie Tang
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Quiming Liang
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Andrew R. Jupp
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Timothy C. Johnstone
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Rebecca C. Neu
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Datong Song
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry; Institut fuer Physikalische und Theoretische Chemie; Universitaet Bonn; Beringstrasse 4 53115 Bonn Germany
| | - Douglas W. Stephan
- Department of Chemistry; University of Toronto; 80 St. George St. Toronto Ontario M5S3H6 Canada
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47
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Abstract
The revelation that combinations of Lewis acids and bases for which dative bonding is impeded can activate dihydrogen led to the concept of "frustrated Lewis pairs" (FLPs). Over the past decade, a range of FLP systems and substrate molecules have precipitated a paradigm change in main-group chemistry and metal-free catalysis. The FLP motif has also found application in a growing body of chemical problems in organic synthesis, transition metal and free radical chemistry, materials, enzymatic models, and surface chemistry. The current state of FLP chemistry is assessed herein, and the outlook for the future considered.
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Affiliation(s)
- Douglas W Stephan
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S3H6, Canada
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48
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Eckert H. Advanced Magnetic Resonance Techniques for the Structural Characterization of Aminoxyl Radicals and Their Inorganic-Organic Nanocomposite Systems. Chemistry 2017; 23:5893-5914. [PMID: 27862449 DOI: 10.1002/chem.201604685] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Indexed: 11/10/2022]
Abstract
Electron and nuclear spins are extremely sensitive probes of their local structural and dynamic surroundings. Their Zeeman energy levels are modified by different types of local magnetic and electric fields created by their structural environment, which influence their magnetic resonance condition. For this reason, electron spin resonance (ESR) and nuclear magnetic resonance (NMR) spectroscopies have become extremely powerful tools of structural analysis, which are being widely used for the structural characterization of complex solids. Following a brief introduction into the basic theoretical foundations the most commonly used techniques and their application towards the structural characterization of paramagnetic solids based on aminoxyl radicals and their inorganic-organic nanocomposites will be described. Both ESR and NMR observables are useful for monitoring intermolecular interactions between unpaired electron spins, which are particularly important for the design of organically based ferromagnetic systems. ESR and NMR methods based on this effect can be used for monitoring the synthesis of polynitroxides and for evaluating the catalytic function of aminoxyl intercalation compounds. Finally, the sensitivity of ESR signals to motional dynamics can be exploited for characterizing molecule-surface interactions in nanocomposite systems. In the context of the latter work recently developed signal enhancement strategies are described, using polarization transfer from electron spins to nuclear spins for NMR spectroscopic detection.
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Affiliation(s)
- Hellmut Eckert
- Institut für Physikalische Chemie, WWU Münster, Corrensstraße 30, 48149, Münster, Germany.,Instituto de Física São Carlos, Universidade de São Paulo, CP 369, 13560-970, São Carlos, S.P., Brasil
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49
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Kehr G, Erker G. Frustrated Lewis Pair Chemistry: Searching for New Reactions. CHEM REC 2017; 17:803-815. [DOI: 10.1002/tcr.201700010] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Indexed: 01/26/2023]
Affiliation(s)
- Gerald Kehr
- Organisch-Chemisches Institut; Westfälische Wilhelms-Universität; 48149 Münster Corrensstr. 40 Germany
| | - Gerhard Erker
- Organisch-Chemisches Institut; Westfälische Wilhelms-Universität; 48149 Münster Corrensstr. 40 Germany
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50
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Wang T, Wang L, Daniliuc CG, Samigullin K, Wagner M, Kehr G, Erker G. CO/CO and NO/NO coupling at a hidden frustrated Lewis pair template. Chem Sci 2017; 8:2457-2463. [PMID: 28451352 PMCID: PMC5369402 DOI: 10.1039/c6sc04459j] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 12/26/2016] [Indexed: 01/21/2023] Open
Abstract
N-Allyltetramethylpiperidine is readily isomerized to the corresponding enamine by treatment with catalytic amounts of B(C6F5)3. It adds HB(C6F5)2 at the nucleophilic enamine carbon atom to form a C/B Lewis adduct. This reacts with two molar equivalents of carbon monoxide by selective head to tail coupling to give a five-membered C2O2B heterocycle. In contrast the enamine/HB(C6F5)2 Lewis pair reacts with two molar equiv. of nitric oxide by head to head coupling. This reaction probably proceeds via equilibrium with the corresponding vicinal N/B Lewis pair. Most products were characterized by X-ray diffraction.
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Affiliation(s)
- Tongdao Wang
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany .
| | - Long Wang
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany .
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany .
| | - Kamil Samigullin
- Institut für Anorganische und Analytische Chemie , Goethe-Universität Frankfurt , Max-von-Laue-Straße 7 , 60438 Frankfurt am Main , Germany
| | - Matthias Wagner
- Institut für Anorganische und Analytische Chemie , Goethe-Universität Frankfurt , Max-von-Laue-Straße 7 , 60438 Frankfurt am Main , Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany .
| | - Gerhard Erker
- Organisch-Chemisches Institut , Westfälische Wilhelms-Universität Münster , Corrensstraße 40 , 48149 Münster , Germany .
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