1
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Jiao Z, Jaunich KT, Tao T, Gottschall O, Hughes MM, Turlik A, Schuppe AW. Unified Approach to Deamination and Deoxygenation Through Isonitrile Hydrodecyanation: A Combined Experimental and Computational Investigation. Angew Chem Int Ed Engl 2024; 63:e202405779. [PMID: 38619535 DOI: 10.1002/anie.202405779] [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: 03/25/2024] [Revised: 04/13/2024] [Accepted: 04/15/2024] [Indexed: 04/16/2024]
Abstract
Herein, we describe a general hydrodefunctionalization protocol of alcohols and amines through a common isonitrile intermediate. To cleave the relatively inert C-NC bond, we leveraged dual hydrogen atom transfer (HAT) and photoredox catalysis to generate a nucleophilic boryl radical, which readily forms an imidoyl radical intermediate from the isonitrile. Rapid β-scission then accomplishes defunctionalization. This method has been applied to the hydrodefunctionalization of both amine and alcohol-containing pharmaceuticals, natural products, and biomolecules. We extended this approach to the reduction of carbonyls and olefins to their saturated counterparts, as well as the hydrodecyanation of alkyl nitriles. Both experimental and computational studies demonstrate a facile β-scission of the imidoyl radical, and reconcile differences in reactivity between nitriles and isonitriles within our protocol.
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Affiliation(s)
- Ziqi Jiao
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Ln, Nashville, TN, 37240, USA
| | - Kyle T Jaunich
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Ln, Nashville, TN, 37240, USA
| | - Thomas Tao
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY, 12866, USA
| | - Olivia Gottschall
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY, 12866, USA
| | - Maxwell M Hughes
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Ln, Nashville, TN, 37240, USA
| | - Aneta Turlik
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY, 12866, USA
| | - Alexander W Schuppe
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Ln, Nashville, TN, 37240, USA
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2
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Korotenko V, Zipse H. The stability of oxygen-centered radicals and its response to hydrogen bonding interactions. J Comput Chem 2024; 45:101-114. [PMID: 37747356 DOI: 10.1002/jcc.27221] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/10/2023] [Accepted: 08/11/2023] [Indexed: 09/26/2023]
Abstract
The stability of various alkoxy/aryloxy/peroxy radicals, as well as TEMPO and triplet dioxygen (3 O2 ) has been explored at a variety of theoretical levels. Good correlations between RSEtheor and RSEexp are found for hybrid DFT methods, for compound schemes such as G3B3-D3, and also for DLPNO-CCSD(T) calculations. The effects of hydrogen bonding interactions on the stability of oxygen-centered radicals have been probed by addition of a single solvating water molecule. While this water molecule always acts as a H-bond donor to the oxygen-centered radical itself, it can act as a H-bond donor or acceptor to the respective closed-shell parent.
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Affiliation(s)
| | - Hendrik Zipse
- Department of Chemistry, LMU Munich, Munich, Germany
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3
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Biremond T, Riomet M, Jubault P, Poisson T. Photocatalytic and Electrochemical Borylation and Silylation Reactions. CHEM REC 2023; 23:e202300172. [PMID: 37358334 DOI: 10.1002/tcr.202300172] [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: 05/10/2023] [Revised: 06/05/2023] [Indexed: 06/27/2023]
Abstract
Due to their high versatility borylated and silylated compounds are inevitable synthons for organic chemists. To escape the classical hydroboration/hydrosilylation paradigm, chemists turned their attention to more modern and green methods such as photoredox chemistry and electrosynthesis. This account focuses on novel methods for the generation of boryl and silyl radicals to forge C-B and C-Si bonds from our group.
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Affiliation(s)
- Tony Biremond
- Normandie Univ., INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000, Rouen, France
| | - Margaux Riomet
- Normandie Univ., INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000, Rouen, France
| | - Philippe Jubault
- Normandie Univ., INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000, Rouen, France
| | - Thomas Poisson
- Normandie Univ., INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000, Rouen, France
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4
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Nazish M, Legendre CM, Ding Y, Schluschaß B, Schwederski B, Herbst-Irmer R, Parvathy P, Parameswaran P, Stalke D, Kaim W, Roesky HW. A Neutral Borylene and its Conversion to a Radical by Selective Hydrogen Transfer. Inorg Chem 2023. [PMID: 37294916 DOI: 10.1021/acs.inorgchem.3c00211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A successful selective reduction of X2B-Tip (Tip = 1,3,5-iPr3-C6H2, X = I, Br) with KC8 and Mg metal, respectively, in the presence of a hybrid ligand (C6H4(PPh2)LSi) leads to a stable low-valent five-membered ring as a boryl radical [C6H4(PPh2)LSiBTip][Br] (1) and neutral borylene [C6H4(PPh2)LSiBTip] (2). Compound 2 reacts with 1,4-cyclohexadiene, resulting in hydrogen abstraction to afford the radical [C6H4(PPh2)LSiB(H)Tip] (3). Quantum chemical studies reveal that compound 1 is a B-centered radical, and compound 2 is a phosphane and silylene stabilized neutral borylene in a trigonal planar environment, whereas compound 3 is an amidinate-centered radical. Although compounds 1 and 2 are stabilized by hyperconjugation and π-conjugation, they display high H-abstraction energy and basicity, respectively.
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Affiliation(s)
- Mohd Nazish
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Christina M Legendre
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Yi Ding
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Bastian Schluschaß
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Brigitte Schwederski
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Regine Herbst-Irmer
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Parameswaran Parvathy
- Department of Chemistry, National Institute of Technology Calicut, Kerala 673601, India
| | - Pattiyil Parameswaran
- Department of Chemistry, National Institute of Technology Calicut, Kerala 673601, India
| | - Dietmar Stalke
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Wolfgang Kaim
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Herbert W Roesky
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstrasse 4, 37077 Göttingen, Germany
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5
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Breitwieser K, Bahmann H, Weiss R, Munz D. Gauging Radical Stabilization with Carbenes. Angew Chem Int Ed Engl 2022; 61:e202206390. [PMID: 35796423 PMCID: PMC9545232 DOI: 10.1002/anie.202206390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Indexed: 11/29/2022]
Abstract
Carbenes, including N‐heterocyclic carbene (NHC) ligands, are used extensively to stabilize open‐shell transition metal complexes and organic radicals. Yet, it remains unknown, which carbene stabilizes a radical well and, thus, how to design radical‐stabilizing C‐donor ligands. With the large variety of C‐donor ligands experimentally investigated and their electronic properties established, we report herein their radical‐stabilizing effect. We show that radical stabilization can be understood by a captodative frontier orbital description involving π‐donation to‐ and π‐donation from the carbenes. This picture sheds a new perspective on NHC chemistry, where π‐donor effects usually are assumed to be negligible. Further, it allows for the intuitive prediction of the thermodynamic stability of covalent radicals of main group‐ and transition metal carbene complexes, and the quantification of redox non‐innocence.
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Affiliation(s)
- Kevin Breitwieser
- Coordination Chemistry Saarland University Campus C4.1 66123 Saarbrücken Germany
| | - Hilke Bahmann
- Physical and Theoretical Chemistry Saarland University Campus B2.2 66123 Saarbrücken Germany
| | - Robert Weiss
- Organische Chemie Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg Henkestr. 42 91054 Erlangen Germany
| | - Dominik Munz
- Coordination Chemistry Saarland University Campus C4.1 66123 Saarbrücken Germany
- Inorganic and General Chemistry Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg Egerlandstr. 1 91058 Erlangen Germany
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6
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Breitwieser K, Bahmann H, Weiss R, Munz D. Gauging Radical Stabilization with Carbenes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202206390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kevin Breitwieser
- Saarland University: Universitat des Saarlandes Coordination Chemistry GERMANY
| | - Hilke Bahmann
- Saarland University: Universitat des Saarlandes Theoretical Chemistry GERMANY
| | - Robert Weiss
- FAU Erlangen Nuremberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Organic Chemistry GERMANY
| | - Dominik Munz
- Universitat des Saarlandes Inorganic Chemistry: Coordination Chemistry Campus C 4.1 66123 Saarbrücken GERMANY
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7
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Ding Z, Liu Z, Wang Z, Yu T, Xu M, Wen J, Yang K, Zhang H, Xu L, Li P. Catalysis with Diboron(4)/Pyridine: Application to the Broad-Scope [3 + 2] Cycloaddition of Cyclopropanes and Alkenes. J Am Chem Soc 2022; 144:8870-8882. [PMID: 35532758 DOI: 10.1021/jacs.2c03673] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In contrast to the extensive but non-recyclable use of tetraalkoxydiboron(4) compounds as stoichiometric reagents in diverse reactions, this article reports an atom-economical reaction using a commercial diboron(4) as the catalyst. The key to success was designing a catalytic cycle for radical [3 + 2] cycloaddition involving a pyridine cocatalyst to generate from the diboron(4) catalyst and reversibly mediate the transfer of boronyl radicals. In comparison with known [3 + 2] cycloaddition with transition metal-based catalysts, the current reaction features not only metal-free conditions, inexpensive and stable catalysts, and simple operation but also remarkably broadened substrate scope. In particular, previously unusable cyclopropyl ketones without an activating group and/or alkenes with 1,2-disubstitution and 1,1,2-trisubstitution patterns were successfully used for the first time. Consequently, challenging cyclopentane compounds with various levels of substitution (65 examples, 57 new products, up to six substituents at all five ring atoms) were readily prepared in generally high to excellent yield and diastereoselectivity. The reaction was also successfully applied in concise formal synthesis of an anti-obesity drug and building natural product-like complex bridged or spirocyclic compounds. Mechanistic experiments and computational investigation support the proposed radical relay catalysis featuring a pyridine-assisted boronyl radical catalyst. Overall, this work demonstrates the first approach to use tetraalkoxydiboron(4) compounds as catalysts and may lead to the development of new, green, and efficient transition metal-like boron-catalyzed organic reactions.
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Affiliation(s)
- Zhengwei Ding
- Department of Medicinal Chemistry, School of Pharmacy, Xi'an Jiaotong University, Xi'an 710061, China
| | - Zhi Liu
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710054, China
| | - Zhijun Wang
- School of Chemistry and Chemical Engineering/Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, Shihezi 832003, China
| | - Tao Yu
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710054, China
| | - Ming Xu
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710054, China
| | - Jingru Wen
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710054, China
| | - Kaiyan Yang
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710054, China
| | - Hailong Zhang
- Department of Medicinal Chemistry, School of Pharmacy, Xi'an Jiaotong University, Xi'an 710061, China
| | - Liang Xu
- School of Chemistry and Chemical Engineering/Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, Shihezi 832003, China
| | - Pengfei Li
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710054, China.,State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China
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8
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Dow NW, Pedersen PS, Chen TQ, Blakemore DC, Dechert-Schmitt AM, Knauber T, MacMillan DWC. Decarboxylative Borylation and Cross-Coupling of (Hetero)aryl Acids Enabled by Copper Charge Transfer Catalysis. J Am Chem Soc 2022; 144:6163-6172. [PMID: 35377627 DOI: 10.1021/jacs.2c01630] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We report a copper-catalyzed strategy for arylboronic ester synthesis that exploits photoinduced ligand-to-metal charge transfer (LMCT) to convert (hetero)aryl acids into aryl radicals amenable to ambient-temperature borylation. This near-UV process occurs under mild conditions, requires no prefunctionalization of the native acid, and operates broadly across diverse aryl, heteroaryl, and pharmaceutical substrates. We also report a one-pot procedure for decarboxylative cross-coupling that merges catalytic LMCT borylation and palladium-catalyzed Suzuki-Miyaura arylation, vinylation, or alkylation with organobromides to access a range of value-added products. The utility of these protocols is highlighted through the development of a heteroselective double-decarboxylative C(sp2)-C(sp2) coupling sequence, pairing copper-catalyzed LMCT borylation and halogenation processes of two distinct acids (including pharmaceutical substrates) with subsequent Suzuki-Miyaura cross-coupling.
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Affiliation(s)
- Nathan W Dow
- Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544, United States
| | - P Scott Pedersen
- Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544, United States
| | - Tiffany Q Chen
- Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544, United States
| | - David C Blakemore
- Worldwide Research and Development, Pfizer, Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Anne-Marie Dechert-Schmitt
- Worldwide Research and Development, Pfizer, Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Thomas Knauber
- Worldwide Research and Development, Pfizer, Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - David W C MacMillan
- Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544, United States
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9
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Zeng J, Dong S, Dai C, Zhu J. Predicting Dinitrogen Activation by Five-Electron Boron-Centered Radicals. Inorg Chem 2022; 61:2234-2241. [PMID: 35044758 DOI: 10.1021/acs.inorgchem.1c03546] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Due to the high bond dissociation energy (945 kJ mol-1) and the large highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap (10.8 eV), dinitrogen activation under mild conditions is extremely challenging. On the other hand, the conventional Haber-Bosch ammonia synthesis under harsh conditions consumes more than 1% of the world's annual energy supply. Thus, it is important and urgent to develop an alternative approach for dinitrogen activation under mild conditions. In comparison with transition metals, main group compounds are less explored for nitrogen activation. Here, we carry out density functional theory calculation to screen boron radicals for dinitrogen activation. As a result, the experimentally available seven-electron boron-centered radicals are found to be inactive to N2 activation, whereas some five-electron boron-centered radicals become favorable for dinitrogen activation, inviting experimental chemists' examination. The principal interacting spin-orbital analyses suggest that a five-electron boron-centered radical can mimic a transition metal on a synergic interaction with dinitrogen in the transition states.
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Affiliation(s)
- Jie Zeng
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Shicheng Dong
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Chenshu Dai
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Jun Zhu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
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10
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Abstract
A simple electrochemically mediated method for the conversion of alkyl carboxylic acids to their borylated congeners is presented. This protocol features an undivided cell setup with inexpensive carbon-based electrodes and exhibits a broad substrate scope and scalability in both flow and batch reactors. The use of this method in challenging contexts is exemplified with a modular formal synthesis of jawsamycin, a natural product harboring five cyclopropane rings.
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11
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A radical approach for the selective C-H borylation of azines. Nature 2021; 595:677-683. [PMID: 34015802 DOI: 10.1038/s41586-021-03637-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 05/12/2021] [Indexed: 02/04/2023]
Abstract
Boron functional groups are often introduced in place of aromatic carbon-hydrogen bonds to expedite small-molecule diversification through coupling of molecular fragments1-3. Current approaches based on transition-metal-catalysed activation of carbon-hydrogen bonds are effective for the borylation of many (hetero)aromatic derivatives4,5 but show narrow applicability to azines (nitrogen-containing aromatic heterocycles), which are key components of many pharmaceutical and agrochemical products6. Here we report an azine borylation strategy using stable and inexpensive amine-borane7 reagents. Photocatalysis converts these low-molecular-weight materials into highly reactive boryl radicals8 that undergo efficient addition to azine building blocks. This reactivity provides a mechanistically alternative tactic for sp2 carbon-boron bond assembly, where the elementary steps of transition-metal-mediated carbon-hydrogen bond activation and reductive elimination from azine-organometallic intermediates are replaced by a direct, Minisci9-style, radical addition. The strongly nucleophilic character of the amine-boryl radicals enables predictable and site-selective carbon-boron bond formation by targeting the azine's most activated position, including the challenging sites adjacent to the basic nitrogen atom. This approach enables access to aromatic sites that elude current strategies based on carbon-hydrogen bond activation, and has led to borylated materials that would otherwise be difficult to prepare. We have applied this process to the introduction of amine-borane functionalities to complex and industrially relevant products. The diversification of the borylated azine products by mainstream cross-coupling technologies establishes aromatic amino-boranes as a powerful class of building blocks for chemical synthesis.
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12
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Tian YM, Guo XN, Braunschweig H, Radius U, Marder TB. Photoinduced Borylation for the Synthesis of Organoboron Compounds. Chem Rev 2021; 121:3561-3597. [PMID: 33596057 DOI: 10.1021/acs.chemrev.0c01236] [Citation(s) in RCA: 129] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Organoboron compounds have important synthetic value and can be applied in numerous transformations. The development of practical and convenient ways to synthesize boronate esters has thus attracted significant interest. Photoinduced borylations originated from stoichiometric reactions of alkanes and arenes with well-defined metal-boryl complexes. Now, photoredox-initiated borylations, catalyzed by either transition metal or organic photocatalysts, and photochemical borylations with high efficiency have become a burgeoning area of research. In this Focus Review, we summarize research on photoinduced borylations, especially emphasizing recent developments and trends. This includes the photoinduced borylation of arenes, alkanes, aryl/alkyl halides, activated carboxylic acids, amines, alcohols, and so on based on transition metal catalysis, metal-free organocatalysis, and direct photochemical activation. We focus on reaction mechanisms involving single-electron transfer, triplet-energy transfer, and other radical processes.
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Affiliation(s)
- Ya-Ming Tian
- Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Xiao-Ning Guo
- Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Holger Braunschweig
- Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Udo Radius
- Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Todd B Marder
- Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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13
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Han J, San HH, Guo A, Wang L, Tang X. Boryl Radical‐Mediated C−H Activation of Inactivated Alkanes for the Synthesis of Internal Alkynes. Adv Synth Catal 2020. [DOI: 10.1002/adsc.202000772] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Jia‐Bin Han
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
| | - Htet Htet San
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
- Department of Industrial Chemistry Yadanabon University Amarapura Township Mandalay Region 05063 People's Republic of Myanmar
| | - Ao Guo
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
| | - Long Wang
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
| | - Xiang‐Ying Tang
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Huazhong University of Science and Technology 1037 Luoyu Road Wuhan 430074 People's Republic of China
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14
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Xia P, Song D, Ye Z, Hu Y, Xiao J, Xiang H, Chen X, Yang H. Photoinduced Single‐Electron Transfer as an Enabling Principle in the Radical Borylation of Alkenes with NHC–Borane. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201913398] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Peng‐Ju Xia
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Dan Song
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Zhi‐Peng Ye
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Yuan‐Zhuo Hu
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Jun‐An Xiao
- Guangxi Key Laboratory of Natural Polymer Chemistry and PhysicsNanning Normal University Nanning 530001 Guangxi P. R. China
| | - Hao‐Yue Xiang
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Xiao‐Qing Chen
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
- Key Laboratory of Hunan Province for Water Environment and Agriculture Product SafetyCentral South University Changsha 410083 P. R. China
| | - Hua Yang
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
- Key Laboratory of Hunan Province for Water Environment and Agriculture Product SafetyCentral South University Changsha 410083 P. R. China
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15
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Xu W, Jiang H, Leng J, Ong H, Wu J. Visible‐Light‐Induced Selective Defluoroborylation of Polyfluoroarenes,
gem
‐Difluoroalkenes, and Trifluoromethylalkenes. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201911819] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Wengang Xu
- Department of Chemistry National University of Singapore 3 Science Drive 3 Singapore 117543 Singapore
- College of New Energy, Institute of New Energy State Key Laboratory of Heavy Oil Processing China University of Petroleum (East China) Qingdao 266580 P. R. China
| | - Heming Jiang
- Laboratory of Computational Chemistry & Drug Design State Key Laboratory of Chemical Oncogenomics Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
| | - Jing Leng
- Department of Chemistry National University of Singapore 3 Science Drive 3 Singapore 117543 Singapore
- State Key Laboratory of Silicate Materials for Architectures Wuhan University of Technology 122 Luoshi Road Wuhan Hubei 430070 P. R. China
| | - Han‐Wee Ong
- Department of Chemistry National University of Singapore 3 Science Drive 3 Singapore 117543 Singapore
| | - Jie Wu
- Department of Chemistry National University of Singapore 3 Science Drive 3 Singapore 117543 Singapore
- National University of Singapore (Suzhou) Research Institute 377 Lin Quan Street, Suzhou Industrial Park Suzhou Jiangsu 215123 P. R. China
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16
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Xu W, Jiang H, Leng J, Ong HW, Wu J. Visible-Light-Induced Selective Defluoroborylation of Polyfluoroarenes, gem-Difluoroalkenes, and Trifluoromethylalkenes. Angew Chem Int Ed Engl 2020; 59:4009-4016. [PMID: 31851417 DOI: 10.1002/anie.201911819] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 12/07/2019] [Indexed: 11/10/2022]
Abstract
Fluorinated organoboranes serve as versatile synthetic precursors for the preparation of value-added fluorinated organic compounds. Recent progress has been mainly focused on the transition-metal catalyzed defluoroborylation. Herein, we report a photocatalytic defluoroborylation platform through direct B-H activation of N-heterocyclic carbene boranes, through the synergistic merger of a photoredox catalyst and a hydrogen atom transfer catalyst. This atom-economic and operationally simple protocol has enabled defluoroborylation of an extremely broad scope of multifluorinated substrates including polyfluoroarenes, gem-difluoroalkenes, and trifluoromethylalkenes in a highly selective fashion. Intriguingly, the defluoroborylation protocol can be transition-metal free, and the regioselectivity obtained is complementary to the reported transition-metal-catalysis in many cases.
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Affiliation(s)
- Wengang Xu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.,College of New Energy, Institute of New Energy, State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao, 266580, P. R. China
| | - Heming Jiang
- Laboratory of Computational Chemistry & Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China
| | - Jing Leng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.,State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Wuhan, Hubei, 430070, P. R. China
| | - Han-Wee Ong
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Jie Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.,National University of Singapore (Suzhou) Research Institute, 377 Lin Quan Street, Suzhou Industrial Park, Suzhou, Jiangsu, 215123, P. R. China
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17
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Xia PJ, Song D, Ye ZP, Hu YZ, Xiao JA, Xiang HY, Chen XQ, Yang H. Photoinduced Single-Electron Transfer as an Enabling Principle in the Radical Borylation of Alkenes with NHC-Borane. Angew Chem Int Ed Engl 2020; 59:6706-6710. [PMID: 31849140 DOI: 10.1002/anie.201913398] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 11/28/2019] [Indexed: 11/06/2022]
Abstract
A photoinduced SET process enables the direct B-H bond activation of NHC-boranes. In contrast to common hydrogen atom transfer (HAT) strategies, this photoinduced reaction simply takes advantage of the beneficial redox potentials of NHC-boranes, thus obviating the need for extra radical initiators. The resulting NHC-boryl radical was used for the borylation of a wide range of α-trifluoromethylalkenes and alkenes with diverse electronic and structural features, providing facile access to highly functionalized borylated molecules. Labeling and photoquenching experiments provide insight into the mechanism of this photoinduced SET pathway.
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Affiliation(s)
- Peng-Ju Xia
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Dan Song
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Zhi-Peng Ye
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Yuan-Zhuo Hu
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Jun-An Xiao
- Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning, 530001, Guangxi, P. R. China
| | - Hao-Yue Xiang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Xiao-Qing Chen
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China.,Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Central South University, Changsha, 410083, P. R. China
| | - Hua Yang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China.,Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Central South University, Changsha, 410083, P. R. China
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18
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Dai W, Geib SJ, Curran DP. Facile Synthesis of α-N-Heterocyclic Carbene-Boryl Ketones from N-Heterocyclic Carbene-Boranes and Alkenyl Triflates. J Am Chem Soc 2019; 141:12355-12361. [DOI: 10.1021/jacs.9b05547] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Wen Dai
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15208, United States
| | - Steven J. Geib
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15208, United States
| | - Dennis P. Curran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15208, United States
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19
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von Grotthuss E, Prey SE, Bolte M, Lerner HW, Wagner M. Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts. J Am Chem Soc 2019; 141:6082-6091. [DOI: 10.1021/jacs.9b01998] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Esther von Grotthuss
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, Frankfurt am Main D-60438, Germany
| | - Sven E. Prey
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, Frankfurt am Main D-60438, Germany
| | - Michael Bolte
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, Frankfurt am Main D-60438, Germany
| | - Hans-Wolfram Lerner
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, Frankfurt am Main D-60438, Germany
| | - Matthias Wagner
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, Frankfurt am Main D-60438, Germany
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20
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Dai W, Curran DP, Walton JC. EPR and Preparative Studies of 5- endo Cyclizations of Radicals Derived from Alkenyl NHC-Boranes Bearing tert-Butyl Ester Substituents. J Org Chem 2019; 84:2102-2111. [PMID: 30663305 DOI: 10.1021/acs.joc.8b03112] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Radical H atom abstraction from a set of N-heterocyclic carbene (NHC) complexes of alkenylboranes bearing two tert-butyl ester substituents was studied by EPR spectroscopy. The initial boraallyl radical intermediates rapidly ring closed onto the O atoms of their distal ester groups in 5- endo mode to yield 1,2-oxaborole radicals. Unexpectedly, two structural varieties of these radicals were identified from their EPR spectra. These proved to be two stable rotamers, in which the carbonyl group of the tert-butyl ester was oriented toward and away from the NHC ring. These rotamers were akin to the s- trans and s- cis rotamers of α,β-unsaturated carbonyl compounds. Their stability was attributed to the quasi-allylic interaction of their unpaired electrons with the carbonyl units of their adjacent ester groups. EPR spectroscopic evidence for two rotamers of the analogous methyl ester containing NHC-oxaborole radicals was also obtained. An improved synthetic procedure for preparing rare NHC-boralactones was developed involving treatment of the alkenyl NHC-boranes with AIBN and tert-dodecanethiol.
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Affiliation(s)
- Wen Dai
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Dennis P Curran
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - John C Walton
- EaStCHEM School of Chemistry , University of St. Andrews , St. Andrews , Fife KY16 9ST , United Kingdom
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21
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Feng R, Yang W, Wang W, Zhao Y, Tan G, Zhang L, Wang X. Isolable diboryl radicals acting as highly efficient reaction intermediates under mild conditions. Chem Commun (Camb) 2019; 55:12908-12911. [DOI: 10.1039/c9cc06514h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Activation of the B–B bond in diborane with dimesitylpyridyl boranes afforded the stable diboryl radicals in moderate yields.
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Affiliation(s)
- Rui Feng
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Wenbang Yang
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Wenqing Wang
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Gengwen Tan
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Li Zhang
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
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22
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Dai W, McFadden TR, Curran DP, Früchtl HA, Walton JC. 5- Endo Cyclizations of NHC-Boraallyl Radicals Bearing Ester Substituents: Characterization of Derived 1,2-Oxaborole Radicals and Boralactones. J Am Chem Soc 2018; 140:15868-15875. [PMID: 30369236 DOI: 10.1021/jacs.8b09288] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
EPR studies of radical hydrogen abstraction reactions of N-heterocyclic carbene (NHC) complexes of alkenylboranes bearing two ester substituents revealed not the expected boraallyl radicals but instead isomeric 1,2-oaxborole radicals. Such radicals are new, and DFT calculations show that they arise from the initially formed boraallyl radicals by a rapid, exothermic 5- endo cyclization. These spectroscopic and computational discoveries prompted a series of preparative experiments that provided access to a novel family of robust NHC-boralactones. A one-pot procedure was developed to access the boralactones directly from an NHC-borane (NHC-BH3) and dimethyl acetylenedicarboxylate.
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Affiliation(s)
- Wen Dai
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Timothy R McFadden
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Dennis P Curran
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Herbert A Früchtl
- EaStCHEM School of Chemistry , University of St. Andrews , St. Andrews , Fife KY16 9ST , United Kingdom
| | - John C Walton
- EaStCHEM School of Chemistry , University of St. Andrews , St. Andrews , Fife KY16 9ST , United Kingdom
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23
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Wu J, He L, Noble A, Aggarwal VK. Photoinduced Deaminative Borylation of Alkylamines. J Am Chem Soc 2018; 140:10700-10704. [PMID: 30091912 DOI: 10.1021/jacs.8b07103] [Citation(s) in RCA: 261] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
An operationally simple deaminative borylation reaction of primary alkylamines has been developed. The formation of electron-donor-acceptor complexes between N-alkylpyridinium salts and bis(catecholato)diboron enables photoinduced single-electron transfer and fragmentation to carbon-centered radicals, which are subsequently borylated. The mild conditions allow a diverse range of readily available alkylamines to be efficiently converted into synthetically valuable alkylboronic esters under catalyst-free conditions.
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Affiliation(s)
- Jingjing Wu
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , United Kingdom
| | - Lin He
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , United Kingdom
| | - Adam Noble
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , United Kingdom
| | - Varinder K Aggarwal
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , United Kingdom
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24
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Guo A, Han JB, Tang XY. Boryl Radicals-Triggered Selective C-H Functionalization for the Synthesis of Diverse Phenanthridine Derivatives. Org Lett 2018; 20:2351-2355. [PMID: 29584434 DOI: 10.1021/acs.orglett.8b00642] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A boryl radical-triggered C-H functionalization of aliphatic ethers/amines or DMF with isocyanides is developed to deliver diverse phenanthridine derivatives in good to excellent yields. The substrate scope is broad, and a wide range of functional groups are tolerated under the standard conditions. The rapid removal of HBPin species by 4-cyanopyridine 1-oxide provides the driving force for this reaction. This new method should make boryl radicals widely applicable in organic synthesis.
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Affiliation(s)
- Ao Guo
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica , Huazhong University of Science and Technology , 1037 Luoyu Road , Wuhan 430074 , People's Republic of China
| | - Jia-Bin Han
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica , Huazhong University of Science and Technology , 1037 Luoyu Road , Wuhan 430074 , People's Republic of China
| | - Xiang-Ying Tang
- School of Chemistry and Chemical Engineering and Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica , Huazhong University of Science and Technology , 1037 Luoyu Road , Wuhan 430074 , People's Republic of China
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25
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Soulard V, Villa G, Vollmar DP, Renaud P. Radical Deuteration with D 2O: Catalysis and Mechanistic Insights. J Am Chem Soc 2017; 140:155-158. [PMID: 29240406 DOI: 10.1021/jacs.7b12105] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Selective incorporation of deuterium atoms into molecules is of high interest for labeling purposes and for optimizing properties of drug candidates. A mild and environmentally benign method for the deuteration of alkyl iodides via radical pathway using D2O as source of deuterium has been developed. The reaction is initiated and mediated by triethylborane in the presence of dodecanethiol as a catalyst. This method is compatible with a wide range of functional groups and provides the monodeuterated products in good yields and with a high level of deuterium incorporation. It opens promising opportunities for the development of enantioselective radical reactions. Moreover, a revision of the mechanism of the deoxygenation reaction of xanthates using R3B and water (Wood deoxygenation) is presented.
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Affiliation(s)
- Valentin Soulard
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Giorgio Villa
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Denis Patrick Vollmar
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Philippe Renaud
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
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26
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Polezhaev AV, Liss CJ, Telser J, Chen C, Caulton KG. A PNNH Pincer Ligand Allows Access to Monovalent Iron. Chemistry 2017; 24:1330-1341. [DOI: 10.1002/chem.201703795] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Indexed: 12/21/2022]
Affiliation(s)
| | - Cameron J. Liss
- Department of Biological, Chemical, and Physical Sciences Roosevelt University 430 S. Michigan Ave Chicago Illinois 60605 USA
| | - Joshua Telser
- Department of Biological, Chemical, and Physical Sciences Roosevelt University 430 S. Michigan Ave Chicago Illinois 60605 USA
| | - Chun‐Hsing Chen
- Department of Chemistry Indiana University Bloomington 47405 Bloomington IN USA
| | - Kenneth G. Caulton
- Department of Chemistry Indiana University Bloomington 47405 Bloomington IN USA
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27
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Yu YJ, Zhang FL, Cheng J, Hei JH, Deng WT, Wang YF. Lewis Base–Boryl Radicals Enabled the Desulfurizative Reduction and Annulation of Thioamides. Org Lett 2017; 20:24-27. [DOI: 10.1021/acs.orglett.7b03201] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- You-Jie Yu
- Hefei National Laboratory
for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Feng-Lian Zhang
- Hefei National Laboratory
for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Jie Cheng
- Hefei National Laboratory
for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Jing-Hao Hei
- Hefei National Laboratory
for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Wei-Ting Deng
- Hefei National Laboratory
for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Yi-Feng Wang
- Hefei National Laboratory
for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
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28
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29
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Watanabe T, Geib SJ, Curran DP, Taniguchi T. N-Heterocyclic Carbene Boranes are Hydrogen Donors in Masamune-Bergman Reactions of Benzo[3,4]cyclodec-3-ene-1,5-diynes. J Org Chem 2017; 82:13034-13042. [PMID: 29120175 DOI: 10.1021/acs.joc.7b01981] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thermal reactions of benzo[3,4]cyclodec-3-ene-1,5-diyne with N-heterocyclic carbene boranes (NHC-boranes) provided mixtures of 9-borylated 1,2,3,4-tetrahydroanthracenes along with 1,2,3,4-tetrahydroanthracene. These products indicate that NHC-boranes serve as hydrogen donors to a p-benzyne intermediate formed by the Masamune-Bergman reaction. Experimental results support a radical mechanism in nonpolar solvents, but suggest that ionic mechanisms compete in the production of 1,2,3,4-tetrahydroanthracene when the reaction is performed in a polar solvent.
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Affiliation(s)
- Takashi Watanabe
- School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University , Kakuma-machi, Kanazawa 920-1192, Japan
| | - Steven J Geib
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Dennis P Curran
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Tsuyoshi Taniguchi
- School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University , Kakuma-machi, Kanazawa 920-1192, Japan
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30
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Barth F, Achrainer F, Pütz AM, Zipse H. Aminopyridine-Borane Complexes as Hydrogen Atom Donor Reagents: Reaction Mechanism and Substrate Selectivity. Chemistry 2017; 23:13455-13464. [PMID: 28699670 DOI: 10.1002/chem.201702469] [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: 05/30/2017] [Indexed: 11/12/2022]
Abstract
Lewis base-borane complexes are shown to be potent hydrogen atom donors in radical chain reduction reactions. Results obtained in 1 H, 11 B, and 13 C NMR measurements and kinetic experiments support a complex reaction mechanism involving the parent borane as well as its initial reaction products as active hydrogen atom donors. Efficient reduction reactions of iodides, bromides, and xanthates in apolar solvents rely on initiator systems generating oxygen-centered radicals under thermal conditions and pyridine-borane complexes carrying solubilizing substituents. In contrast to tin hydride reagents, the pyridine-boranes reduce xanthates faster than the corresponding iodides.
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Affiliation(s)
- Florian Barth
- Ludwig-Maximilians-Universität München, Department of Chemistry, Butenandtstr. 5-13, 81377, München, Germany
| | - Florian Achrainer
- Ludwig-Maximilians-Universität München, Department of Chemistry, Butenandtstr. 5-13, 81377, München, Germany
| | - Alexander M Pütz
- Ludwig-Maximilians-Universität München, Department of Chemistry, Butenandtstr. 5-13, 81377, München, Germany
| | - Hendrik Zipse
- Ludwig-Maximilians-Universität München, Department of Chemistry, Butenandtstr. 5-13, 81377, München, Germany
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31
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Fawcett A, Pradeilles J, Wang Y, Mutsuga T, Myers EL, Aggarwal VK. Photoinduced decarboxylative borylation of carboxylic acids. Science 2017; 357:283-286. [DOI: 10.1126/science.aan3679] [Citation(s) in RCA: 379] [Impact Index Per Article: 54.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 06/07/2017] [Indexed: 12/30/2022]
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32
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Ishida S, Ichikawa H, Iwamoto T. Coordination-induced Hydrogen Abstraction in the Reactions of a Stable Dialkylphosphinyl Radical with BH3-Lewis Base Adducts. CHEM LETT 2017. [DOI: 10.1246/cl.170248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Shintaro Ishida
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-8578
| | - Hitomi Ichikawa
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-8578
| | - Takeaki Iwamoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-8578
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33
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Watanabe T, Hirose D, Curran DP, Taniguchi T. Borylative Radical Cyclizations of Benzo[3,4]cyclodec-3-ene-1,5-diynes and N-Heterocyclic Carbene-Boranes. Chemistry 2017; 23:5404-5409. [PMID: 28205265 DOI: 10.1002/chem.201700689] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Indexed: 11/09/2022]
Abstract
Borylative radical cyclization of benzo[3,4]cyclodec-3-ene-1,5-diynes to provide 5-borylated 6,7,8,9-tetrahydrobenzo[a]azulenes has been developed. The experimental results suggest that the reaction proceeds by a radical chain mechanism, in which di-tert-butyl hyponitrite (TBHN) works as a good radical initiator to form boryl radicals from N-heterocyclic carbene-boranes (NHC-boranes). The present reaction is a rare model that illustrates addition of boryl radicals to alkynes.
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Affiliation(s)
- Takashi Watanabe
- School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | - Daisuke Hirose
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | - Dennis P Curran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Tsuyoshi Taniguchi
- School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
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34
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Wu C, Hou X, Zheng Y, Li P, Lu D. Electrophilicity and Nucleophilicity of Boryl Radicals. J Org Chem 2017; 82:2898-2905. [PMID: 28224797 DOI: 10.1021/acs.joc.6b02849] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We carried out a survey of the relative reactivity of a collection of 91 neutral boryl radicals using density functional calculations. Their reactivities were characterized by four indices, i.e., the global electrophilicity, global nucleophilicity, local electrophilicity, and local nucleophilicity. Particularly, the global electrophilicity and nucleophilicity indices span over a moderately wider range than those of carbon radicals, indicating their potentially broader reactivity. Thus, boryl radicals may be utilized in electrophilic radical reactions, while traditionally they are only considered for nucleophilic radical reactions. In contrast, the local electrophilicity and nucleophilicity indices at the boron center show a different reactivity picture than their global counterparts. The inconsistency is rooted in the low and varying spin density on boron (for most radicals, less than 50%) in different boryl radicals, which is a combinative result of radical stabilization via electron delocalization and the low electronegativity of boron (compared to carbon). In short, the boron character in boryl radicals may be weak and their reactivity is not reflected by the local indices based on boron but by the global ones.
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Affiliation(s)
- Chao Wu
- Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an 710054, China
| | - Xiufang Hou
- College of Chemistry and Chemical Engineering, Yan'an University , Yan'an 716000, China
| | - Yuheng Zheng
- Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an 710054, China
| | - Pengfei Li
- Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an 710054, China
| | - Dongmei Lu
- Department of Applied Chemistry, School of Science, Xi'an Jiaotong University , Xi'an 710049, China
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Brea O, Alkorta I, Mó O, Yáñez M, Elguero J, Corral I. Exergonic and Spontaneous Production of Radicals through Beryllium Bonds. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201603690] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Oriana Brea
- Universidad Autónoma de Madrid; Departamento de Química, Facultad de Ciencias, Módulo 13, Campus de Excelencia UAM-CSIC, Cantoblanco; 28049 Madrid Spain
| | - Ibon Alkorta
- Instituto de Química Médica (CSIC).; C/ Juan de la Cierva, 3 28006 Madrid Spain
| | - Otilia Mó
- Universidad Autónoma de Madrid; Departamento de Química, Facultad de Ciencias, Módulo 13, Campus de Excelencia UAM-CSIC, Cantoblanco; 28049 Madrid Spain
| | - Manuel Yáñez
- Universidad Autónoma de Madrid; Departamento de Química, Facultad de Ciencias, Módulo 13, Campus de Excelencia UAM-CSIC, Cantoblanco; 28049 Madrid Spain
| | - José Elguero
- Instituto de Química Médica (CSIC).; C/ Juan de la Cierva, 3 28006 Madrid Spain
| | - Inés Corral
- Universidad Autónoma de Madrid; Departamento de Química, Facultad de Ciencias, Módulo 13, Campus de Excelencia UAM-CSIC, Cantoblanco; 28049 Madrid Spain
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Brea O, Alkorta I, Mó O, Yáñez M, Elguero J, Corral I. Exergonic and Spontaneous Production of Radicals through Beryllium Bonds. Angew Chem Int Ed Engl 2016; 55:8736-9. [DOI: 10.1002/anie.201603690] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Indexed: 12/15/2022]
Affiliation(s)
- Oriana Brea
- Universidad Autónoma de Madrid; Departamento de Química, Facultad de Ciencias, Módulo 13, Campus de Excelencia UAM-CSIC, Cantoblanco; 28049 Madrid Spain
| | - Ibon Alkorta
- Instituto de Química Médica (CSIC).; C/ Juan de la Cierva, 3 28006 Madrid Spain
| | - Otilia Mó
- Universidad Autónoma de Madrid; Departamento de Química, Facultad de Ciencias, Módulo 13, Campus de Excelencia UAM-CSIC, Cantoblanco; 28049 Madrid Spain
| | - Manuel Yáñez
- Universidad Autónoma de Madrid; Departamento de Química, Facultad de Ciencias, Módulo 13, Campus de Excelencia UAM-CSIC, Cantoblanco; 28049 Madrid Spain
| | - José Elguero
- Instituto de Química Médica (CSIC).; C/ Juan de la Cierva, 3 28006 Madrid Spain
| | - Inés Corral
- Universidad Autónoma de Madrid; Departamento de Química, Facultad de Ciencias, Módulo 13, Campus de Excelencia UAM-CSIC, Cantoblanco; 28049 Madrid Spain
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Ledet AD, Hudnall TW. Reduction of a diamidocarbene-supported borenium cation: isolation of a neutral boryl-substituted radical and a carbene-stabilized aminoborylene. Dalton Trans 2016; 45:9820-6. [DOI: 10.1039/c6dt00300a] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have synthesized the first diamidocarbene (DAC)-supported borenium salt which was found to readily undergo two sequential 1-electron reductions to give a boryl-substituted DAC-centred radical and a DAC-supported aminoborylene.
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Affiliation(s)
- Anthony D. Ledet
- Department of Chemistry and Biochemistry
- Texas State University
- San Marcos
- USA
| | - Todd W. Hudnall
- Department of Chemistry and Biochemistry
- Texas State University
- San Marcos
- USA
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Telitel S, Vallet AL, Flanigan DM, Graff B, Morlet-Savary F, Rovis T, Lalevée J, Lacôte E. Influence of Electronic Effects on the Reactivity of Triazolylidene-Boryl Radicals: Consequences for the use of N-Heterocyclic Carbene Boranes in Organic and Polymer Synthesis. Chemistry 2015; 21:13772-7. [PMID: 26239157 PMCID: PMC4986694 DOI: 10.1002/chem.201500499] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Indexed: 11/07/2022]
Abstract
A small library of triazolylidene-boranes that differ only in the nature of the aryl group on the external nitrogen atom was prepared. Their reactivity as hydrogen-atom donors, as well as that of the corresponding N-heterocyclic carbene (NHC)-boryl radicals toward methyl acrylate and oxygen, was investigated by laser flash photolysis, molecular orbital calculations, and ESR spin-trapping experiments, and benchmarked relative to the already known dimethyltriazolylidene-borane. The new NHC-boranes were also used as co-initiators for the Type I photopolymerization of acrylates. This allowed a structure-reactivity relationship with regard to the substitution pattern of the NHC to be established and the role of electronic effects in the reactivity of NHC-boryl radicals to be probed. Although their rate of addition to methyl acrylate depends on their electronegativity, the radicals are all nucleophilic and good initiators for photopolymerization reactions.
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Affiliation(s)
- Sofia Telitel
- Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361, Université de Haute-Alsace, 15 rue Jean Starcky, 68057 Mulhouse Cedex (France), Fax: (+33) 3-89-33-60-69
| | - Anne-Laure Vallet
- ICSN CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex (France)
| | - Darrin M Flanigan
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523 (USA)
| | - Bernadette Graff
- Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361, Université de Haute-Alsace, 15 rue Jean Starcky, 68057 Mulhouse Cedex (France), Fax: (+33) 3-89-33-60-69
| | - Fabrice Morlet-Savary
- Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361, Université de Haute-Alsace, 15 rue Jean Starcky, 68057 Mulhouse Cedex (France), Fax: (+33) 3-89-33-60-69
| | - Tomislav Rovis
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523 (USA)
| | - Jacques Lalevée
- Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361, Université de Haute-Alsace, 15 rue Jean Starcky, 68057 Mulhouse Cedex (France), Fax: (+33) 3-89-33-60-69.
| | - Emmanuel Lacôte
- ICSN CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex (France).
- Université de Lyon, Institut de chimie de Lyon, UMR 5265 CNRS-Université Lyon I-ESCPE Lyon, 43 Bd du 11 novembre 1918, 69616 Villeurbanne Cedex (France), Fax: (+33) 4-72-43-17-95.
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Damodaran K, Li X, Pan X, Curran DP. Dynamic Behavior of N-Heterocyclic Carbene Boranes: Boron–Carbene Bonds in B,B-Disubstituted N,N-Dimethylimidazol-2-ylidene Boranes Have Substantial Rotation Barriers. J Org Chem 2015; 80:4465-9. [DOI: 10.1021/acs.joc.5b00324] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Krishnan Damodaran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Xiben Li
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Xiangcheng Pan
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Dennis P. Curran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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Abstract
In this study, density functional theory calculations, using the M06-2X functional, were performed to investigate the efficiencies of various carbenes in inducing hydrogen abstraction in BH3 through the formation of a Lewis acid–base pair with BH3. The density functional theory results indicate that diamidocarbenes are more efficient in reducing the B–H bond energy of BH3 than diaminocarbenes. Natural bond orbital and combined charge and bond energy analyses were performed to investigate the Lewis acid–base pair formed by BH3 and the title carbenes.
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Isolation of a Neutral Boron‐Containing Radical Stabilized by a Cyclic (Alkyl)(Amino)Carbene. Angew Chem Int Ed Engl 2014; 53:7360-3. [DOI: 10.1002/anie.201403514] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/06/2014] [Indexed: 11/07/2022]
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Bissinger P, Braunschweig H, Damme A, Krummenacher I, Phukan AK, Radacki K, Sugawara S. Isolierung eines neutralen, Bor‐haltigen Radikals, stabilisiert durch ein cyclisches (Alkyl)(amino)carben. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201403514] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Philipp Bissinger
- Institut für Anorganische Chemie, Julius‐Maximilians‐Universität Würzburg, Am Hubland, 97074 Würzburg (Deutschland)
| | - Holger Braunschweig
- Institut für Anorganische Chemie, Julius‐Maximilians‐Universität Würzburg, Am Hubland, 97074 Würzburg (Deutschland)
| | - Alexander Damme
- Institut für Anorganische Chemie, Julius‐Maximilians‐Universität Würzburg, Am Hubland, 97074 Würzburg (Deutschland)
| | - Ivo Krummenacher
- Institut für Anorganische Chemie, Julius‐Maximilians‐Universität Würzburg, Am Hubland, 97074 Würzburg (Deutschland)
| | | | - Krzysztof Radacki
- Institut für Anorganische Chemie, Julius‐Maximilians‐Universität Würzburg, Am Hubland, 97074 Würzburg (Deutschland)
| | - Shun Sugawara
- Department of Chemistry, Graduate School of Science, Hiroshima University (Japan)
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Martín-Sómer A, Mó O, Yáñez M. Are Boryl Radicals from Amine-Boranes and Phosphine-Boranes the Most Stable Radicals? Chemphyschem 2014; 15:2288-94. [DOI: 10.1002/cphc.201402060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Indexed: 11/08/2022]
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Tehfe MA, Schweizer S, Chany AC, Ysacco C, Clément JL, Gigmes D, Morlet-Savary F, Fouassier JP, Neuburger M, Tschamber T, Blanchard N, Lalevée J. On the Synthesis, Characterization and Reactivity of N-Heteroaryl-Boryl Radicals, a New Radical Class Based on Five-Membered Ring Ligands. Chemistry 2014; 20:5054-63. [DOI: 10.1002/chem.201400197] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Indexed: 11/06/2022]
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Lu D, Wu C, Li P. Synergistic Effects of Lewis Bases and Substituents on the Electronic Structure and Reactivity of Boryl Radicals. Chemistry 2014; 20:1630-7. [DOI: 10.1002/chem.201303705] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 11/22/2013] [Indexed: 11/12/2022]
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Affiliation(s)
- Fabrice Dénès
- Laboratoire CEISAM UMR CNRS 6230 - UFR des Sciences et Techniques, Université de Nantes , 2 rue de la Houssinière, BP 92208 - 44322 Nantes Cedex 3, France
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Li X, Curran DP. Insertion of reactive rhodium carbenes into boron-hydrogen bonds of stable N-heterocyclic carbene boranes. J Am Chem Soc 2013; 135:12076-81. [PMID: 23865527 DOI: 10.1021/ja4056245] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Readily available rhodium(II) salts catalyze reactions between NHC-boranes (NHC-BH3) and diazocarbonyl compounds (N2CRCOR'). Stable α-NHC-boryl carbonyl compounds (NHC-BH2-CHRCOR') are isolated in good yields. The reaction is a reliable way to make boron-carbon bonds with good tolerance for variation in both the NHC-borane and diazocarbonyl components. It presumably occurs by insertion of a transient rhodium carbene into a boron-hydrogen bond of the NHC-borane. Competitive experiments show that a typical NHC-borane is highly reactive toward rhodium carbenes.
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Affiliation(s)
- Xiben Li
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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Pan X, Vallet AL, Schweizer S, Dahbi K, Delpech B, Blanchard N, Graff B, Geib SJ, Curran DP, Lalevée J, Lacôte E. Mechanistic and preparative studies of radical chain homolytic substitution reactions of N-heterocyclic carbene boranes and disulfides. J Am Chem Soc 2013; 135:10484-91. [PMID: 23718209 DOI: 10.1021/ja403627k] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Reactions of 1,3-dimethylimidazol-2-ylidene-borane (diMe-Imd-BH3) and related NHC-boranes with diaryl and diheteroaryl disulfides provide diverse NHC-boryl monosulfides (diMe-Imd-BH2SAr) and NHC-boryl disulfides (diMe-Imd-BH(SAr)2). Heating in the dark with 1 equiv of disulfide favors monosulfide formation, while irradiation with 2 equiv disulfide favors disulfide formation. With heteroaryl disulfides, the NHC-borane in the primary NHC-boryl sulfide product migrates from sulfur to nitrogen to give new products with a thioamide substructure. Most substitution reactions are thought to proceed through radical chains in which homolytic substitution of a disulfide by an NHC-boryl radical is a key step. However, with electrophilic disulfides under dark conditions, a competing ionic path may also be possible.
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Affiliation(s)
- Xiangcheng Pan
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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Bissinger P, Braunschweig H, Damme A, Kupfer T, Radacki K. An Electron-Precise, Tetrahedral μ3Boride Complex. Angew Chem Int Ed Engl 2013; 52:7038-41. [DOI: 10.1002/anie.201302828] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Indexed: 11/11/2022]
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