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Abstract
Borenium ions are strong Lewis acids because of the positive charge on boron. While their high reactivity had long restricted their role in organic synthesis to stoichiometric reagents, in the past ten years the introduction of suitable supporting ligands, such as N-heterocyclic carbenes, has enabled them to function as competent catalysts for various organic transformations involving the activation of strong covalent bonds, such as H-H, Si-H, B-H, C-H and C-C bonds. This review provides an overview of the recent advances in borenium-catalysed reactions with emphasis on catalyst synthesis, methodology development and mechanistic insight.
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Affiliation(s)
- Xinyue Tan
- Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Songhu Road 2005, Shanghai, 200438, P. R. China.
| | - Huadong Wang
- Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Songhu Road 2005, Shanghai, 200438, P. R. China.
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Shih DN, Boobalan R, Liu YH, Chein RJ, Chiu CW. [B-Cl-B] + Cations: Chloroborane Masked Chiral Borenium Ions. Inorg Chem 2021; 60:16266-16272. [PMID: 34672549 DOI: 10.1021/acs.inorgchem.1c02073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A tricoordinate borenium ion has received considerable attention in recent years for its applications in Lewis acid catalysis. Over the years, asymmetric catalysis mediated by a chiral borenium ion has also been developed. To stabilize the electron-deficient boron atom, a series of chloroborane masked borenium ions featuring the symmetrical [B-Cl-B]+ linkage are prepared and utilized as the catalyst for the enantioselective Diels-Alder cycloaddition of cyclopentadiene and 2,2,2-trifluoroethyl acrylate. The presence of a Cp* ligand is critical in realizing the cyclic diboron compounds, and the stability of the resulting [B-Cl-B]+ cation is dependent on the steric bulkiness of the oxazolidinone moiety. The stereoselectivity of the Diels-Alder cycloaddition is controlled by the substituents of the chiral oxazolidinone ligand and could be further improved via the coordination of SnCl4 at the bridging chloride of the [B-Cl-B]+ cation.
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Affiliation(s)
- Ding-Nan Shih
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | | | - Yi-Hung Liu
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Rong-Jie Chein
- Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Ching-Wen Chiu
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
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Affiliation(s)
- Anna Widera
- Anorganisch‐Chemisches Institut Ruprecht‐Karls‐Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Erik Filbeck
- Anorganisch‐Chemisches Institut Ruprecht‐Karls‐Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Hans‐Jörg Himmel
- Anorganisch‐Chemisches Institut Ruprecht‐Karls‐Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
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Khoo S, Siu CK, So CW. A Base-Stabilized Silylene-Promoted C(sp3)–H Borylation and H2 Activation. Inorg Chem 2020; 59:9551-9559. [DOI: 10.1021/acs.inorgchem.0c00426] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sabrina Khoo
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Chi-Kit Siu
- Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China
| | - Cheuk-Wai So
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
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Iqbal SA, Pahl J, Yuan K, Ingleson MJ. Intramolecular (directed) electrophilic C-H borylation. Chem Soc Rev 2020; 49:4564-4591. [PMID: 32495755 DOI: 10.1039/c9cs00763f] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
The intramolecular C-H borylation of (hetero)arenes and alkenes using electrophilic boranes is a powerful transition metal free methodology for forming C-B bonds. These C-H borylation reactions are preceded by intermolecular bond (both dative and covalent) formation, with examples proceeding via initial C-B and N-B bond formation dominating this field thus both are discussed in depth herein. Less prevalent intramolecular electrophilic C-H borylation reactions that proceed by intermolecular O-B, S-B and P-B bond formation are also summarised. Mechanistic studies are presented that reveal two mechanisms for C-H borylation, (i) electrophilic aromatic substitution (prevalent with B-X electrophiles); (ii) σ-bond metathesis mediated (prevalent with B-H and B-R electrophiles). To date, intramolecular electrophilic C-H borylation is utilised mainly for accessing boron containing conjugated organic materials, however recent developments, summarized herein alongside early studies, have highlighted the applicability of this methodology for forming synthetically versatile organo-boronate esters and boron containing bioactives. The multitude of synthetic procedures reported for intramolecular electrophilic C-H borylation contain many common features and this enables key requirements for successful C-H borylation and the factors effecting regioselectivity and substrate scope to be identified, discussed and summarized.
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Affiliation(s)
- S A Iqbal
- EastCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | - J Pahl
- EastCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | - K Yuan
- EastCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | - M J Ingleson
- EastCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
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Cid J, Hermann A, Radcliffe JE, Curless LD, Braunschweig H, Ingleson MJ. Synthesis of Unsymmetrical Diboron(5) Compounds and Their Conversion to Diboron(5) Cations. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00288] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jessica Cid
- School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Alexander Hermann
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - James E. Radcliffe
- School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Liam D. Curless
- School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Michael J. Ingleson
- School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom
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Zheng J, Li ZH, Wang H. Addition of dihydrogen to a borylborenium center. Chem Sci 2018; 9:1433-1438. [PMID: 29675190 PMCID: PMC5883945 DOI: 10.1039/c7sc04987k] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 11/27/2017] [Indexed: 11/21/2022] Open
Abstract
The activation of a H-H bond, the simplest covalent bond, is a fundamentally important process. Addition of H2 to an elemental center typically occurs on low valent transition metal or main group complexes through oxidative addition to afford metal dihydride complexes. In contrast, activation of H2 on a high valent center generally results in heterolytic cleavage of the H-H bond to a proton and hydride. Here, we report experimental and computational evidence for the addition of H2 to a borenium center in an N-heterocyclic carbene (NHC) coordinated borylborenium cation, which leads to the formation of a dihydroborenium complex accompanied by the elimination of two σ-bonded substituents, namely mesityl (Mes) and pinacolboryl (Bpin) groups, as mesitylboronic ester.
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Affiliation(s)
- Junhao Zheng
- Department of Chemistry , Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials , Fudan University , Handan Road 220 , Shanghai , 200433 , China . ;
| | - Zhen Hua Li
- Department of Chemistry , Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials , Fudan University , Handan Road 220 , Shanghai , 200433 , China . ;
| | - Huadong Wang
- Department of Chemistry , Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials , Fudan University , Handan Road 220 , Shanghai , 200433 , China . ;
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Zheng J, Fan X, Zhou B, Li ZH, Wang H. Tautomerization of 2,6-lutidines in the presence of B(C6F5)3 using catecholborane as a precatalyst. Chem Commun (Camb) 2016; 52:4655-8. [DOI: 10.1039/c6cc00347h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The Lewis pair of 2,6-lutidine and B(C6F5)3 can undergo tautomerization to produce enamine B(C6F5)3 adducts when catecholborane is applied as a precatalyst.
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Affiliation(s)
- Junhao Zheng
- Collaborative Innovation Center of Chemistry for Energy Material
- Shanghai Key Laboratory of Molecular Catalysis
- Innovative Material
- Department of Chemistry
- Fudan University
| | - Xiaoting Fan
- Collaborative Innovation Center of Chemistry for Energy Material
- Shanghai Key Laboratory of Molecular Catalysis
- Innovative Material
- Department of Chemistry
- Fudan University
| | - Benyu Zhou
- Collaborative Innovation Center of Chemistry for Energy Material
- Shanghai Key Laboratory of Molecular Catalysis
- Innovative Material
- Department of Chemistry
- Fudan University
| | - Zhen Hua Li
- Collaborative Innovation Center of Chemistry for Energy Material
- Shanghai Key Laboratory of Molecular Catalysis
- Innovative Material
- Department of Chemistry
- Fudan University
| | - Huadong Wang
- Collaborative Innovation Center of Chemistry for Energy Material
- Shanghai Key Laboratory of Molecular Catalysis
- Innovative Material
- Department of Chemistry
- Fudan University
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