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Baird SR, Vogels CM, Geier SJ, Watanabe LK, Binder JF, Macdonald CLB, Westcott SA. The phosphinoboration of thiosemicarbazones. CAN J CHEM 2022. [DOI: 10.1139/cjc-2022-0088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This study reports on the exploration of the phosphinoboration reaction with several thiosemicarbazones (R5R4NC(S)NR3N=CR1R2). Reactions between either Ph2PBpin (pin = 1,2-O2C2Me4) or Ph2PBcat (cat = 1,2-O2C6H4) with thiosemicarbazones containing a terminal primary or secondary amine afforded boron-containing heterocyclic 1,3,4-thiadiazoline products in excellent yield. The addition of Ph2PBpin to thiosemicarbazones containing an NMe2 group in the terminal position generated novel five-membered heterocycles in moderate yield, which included boron, sulfur, and nitrogen atoms. Heterocyclization of the thiosemicarbazones occurs preferentially in the presence of functional groups such as acetyl and pyridyl groups.
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Affiliation(s)
- Samuel R. Baird
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB E4L 1G8, Canada
| | - Christopher M. Vogels
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB E4L 1G8, Canada
| | - Stephen J. Geier
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB E4L 1G8, Canada
| | - Lara K. Watanabe
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada
| | - Justin F. Binder
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada
| | | | - Stephen A. Westcott
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB E4L 1G8, Canada
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2
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Grygorenko OO, Moskvina VS, Kleban I, Hryshchyk OV. Synthesis of saturated and partially saturated heterocyclic boronic derivatives. Tetrahedron 2022. [DOI: 10.1016/j.tet.2021.132605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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3
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Dale HJA, Leach AG, Lloyd-Jones GC. Heavy-Atom Kinetic Isotope Effects: Primary Interest or Zero Point? J Am Chem Soc 2021; 143:21079-21099. [PMID: 34870970 DOI: 10.1021/jacs.1c07351] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Chemists have many options for elucidating reaction mechanisms. Global kinetic analysis and classic transition-state probes (e.g., LFERs, Eyring) inevitably form the cornerstone of any strategy, yet their application to increasingly sophisticated synthetic methodologies often leads to a wide range of indistinguishable mechanistic proposals. Computational chemistry provides powerful tools for narrowing the field in such cases, yet wholly simulated mechanisms must be interpreted with great caution. Heavy-atom kinetic isotope effects (KIEs) offer an exquisite but underutilized method for reconciling the two approaches, anchoring the theoretician in the world of calculable observables and providing the experimentalist with atomistic insights. This Perspective provides a personal outlook on this synergy. It surveys the computation of heavy-atom KIEs and their measurement by NMR spectroscopy, discusses recent case studies, highlights the intellectual reward that lies in alignment of experiment and theory, and reflects on the changes required in chemical education in the area.
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Affiliation(s)
- Harvey J A Dale
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
| | - Andrew G Leach
- School of Health Sciences, The University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, U.K
| | - Guy C Lloyd-Jones
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
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4
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Kaplan JA, Issaian A, Stang M, Gorial D, Blum SA. Repurposing π Electrophilic Cyclization/Dealkylation for Group Transfer. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202112351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Joseph A. Kaplan
- Department of Chemistry University of California, Irvine Irvine CA 02697 USA
| | - Adena Issaian
- Department of Chemistry University of California, Irvine Irvine CA 02697 USA
| | - Martin Stang
- Department of Chemistry University of California, Irvine Irvine CA 02697 USA
| | - David Gorial
- Department of Chemistry University of California, Irvine Irvine CA 02697 USA
| | - Suzanne A. Blum
- Department of Chemistry University of California, Irvine Irvine CA 02697 USA
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5
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Kaplan JA, Issaian A, Stang M, Gorial D, Blum SA. Repurposing π Electrophilic Cyclization/Dealkylation for Group Transfer. Angew Chem Int Ed Engl 2021; 60:25776-25780. [PMID: 34585500 DOI: 10.1002/anie.202112351] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Indexed: 01/31/2023]
Abstract
A metal-free regio- and stereocontrolled group-transfer route toward the synthesis of trisubstituted alkenes is described. In this route, an electrophilic heterocyclization is followed by ring-opening group transfer. Specifically, a thioboration reaction transforms readily available alkynyl sulfide precursors into alkenyl boronates and alkenyl sulfides with defined regio- and stereochemistry in one synthetic step using commercially available B-chlorocatecholborane (ClBcat). Mechanistic studies identified the likely pathway as proceeding through zwitterionic rather than haloborated intermediates. The regio- and stereochemistry set in the initial cyclization step is preserved in the final acyclic alkene product, producing alkenes with up to four modifiable substituents with predictable regio- and stereochemistry. Downstream functionalization reactions showcase the versatility of the substitutions of the resulting alkenes. The mechanistic concept maps onto future reaction designs, given the abundance of known electrophiles and nucleophiles for electrophilic heterocyclization/dealkylation sequences.
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Affiliation(s)
- Joseph A Kaplan
- Department of Chemistry, University of California, Irvine, Irvine, CA, 02697, USA
| | - Adena Issaian
- Department of Chemistry, University of California, Irvine, Irvine, CA, 02697, USA
| | - Martin Stang
- Department of Chemistry, University of California, Irvine, Irvine, CA, 02697, USA
| | - David Gorial
- Department of Chemistry, University of California, Irvine, Irvine, CA, 02697, USA
| | - Suzanne A Blum
- Department of Chemistry, University of California, Irvine, Irvine, CA, 02697, USA
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6
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Volochnyuk DM, Gorlova AO, Grygorenko OO. Saturated Boronic Acids, Boronates, and Trifluoroborates: An Update on Their Synthetic and Medicinal Chemistry. Chemistry 2021; 27:15277-15326. [PMID: 34499378 DOI: 10.1002/chem.202102108] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Indexed: 12/13/2022]
Abstract
This review discusses recent advances in the chemistry of saturated boronic acids, boronates, and trifluoroborates. Applications of the title compounds in the design of boron-containing drugs are surveyed, with special emphasis on α-amino boronic derivatives. A general overview of saturated boronic compounds as modern tools to construct C(sp3 )-C and C(sp3 )-heteroatom bonds is given, including recent developments in the Suzuki-Miyaura and Chan-Lam cross-couplings, single-electron-transfer processes including metallo- and organocatalytic photoredox reactions, and transformations of boron "ate" complexes. Finally, an attempt to summarize the current state of the art in the synthesis of saturated boronic acids, boronates, and trifluoroborates is made, with a brief mention of the "classical" methods (transmetallation of organolithium/magnesium reagents with boron species, anti-Markovnikov hydroboration of alkenes, and the modification of alkenyl boron compounds) and a special focus on recent methodologies (boronation of alkyl (pseudo)halides, derivatives of carboxylic acids, alcohols, and primary amines, boronative C-H activation, novel approaches to alkene hydroboration, and 1,2-metallate-type rearrangements).
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Affiliation(s)
- Dmitriy M Volochnyuk
- Enamine Ltd. (www.enamine.net), Chervonotkatska 78, Kyiv, 02094, Ukraine.,Taras Shevchenko National University of Kyiv, Volodymyrska Street 60, Kyiv, 01601, Ukraine.,Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Murmanska Street 5, Kyiv, 02094, Ukraine
| | - Alina O Gorlova
- Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Murmanska Street 5, Kyiv, 02094, Ukraine
| | - Oleksandr O Grygorenko
- Enamine Ltd. (www.enamine.net), Chervonotkatska 78, Kyiv, 02094, Ukraine.,Taras Shevchenko National University of Kyiv, Volodymyrska Street 60, Kyiv, 01601, Ukraine
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7
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Gao C, Blum SA. Main-group metalated heterocycles through Lewis acid cyclization. TRENDS IN CHEMISTRY 2021. [DOI: 10.1016/j.trechm.2021.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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8
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Yang S, Alix A, Bour C, Gandon V. Alkynophilicity of Group 13 MX 3 Salts: A Theoretical Study. Inorg Chem 2021; 60:5507-5522. [PMID: 33769800 DOI: 10.1021/acs.inorgchem.0c03302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The concept of alkynophilicity is revisited with group 13 MX3 metal salts (M = In, Ga, Al, B; X = Cl, OTf) using M06-2X/6-31+G(d,p) calculations. This study aims at answering why some of these salts show reactivity toward enynes that is similar to that observed with late-transition-metal complexes, notably Au(I) species, and why some of them are inactive. For this purpose, the mechanism of the skeletal reorganization of 1,6-enynes into 1-vinylcyclopentenes has been computed, including monomeric ("standard") and dimeric (superelectrophilic) activation. Those results are confronted with deactivation pathways based on the dissociation of the M-X bond. The role of the X ligand in the stabilization of the intermediate nonclassical carbocation is revealed, and the whole features required to make a good π-Lewis acid are discussed.
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Affiliation(s)
- Shengwen Yang
- Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), CNRS UMR 8182, Université Paris-Saclay, Bâtiment 420, 91405 Orsay Cedex, France.,Laboratoire de Chimie Moléculaire (LCM), CNRS UMR 9168, Ecole Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91128 Palaiseau Cedex, France
| | - Aurélien Alix
- Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), CNRS UMR 8182, Université Paris-Saclay, Bâtiment 420, 91405 Orsay Cedex, France
| | - Christophe Bour
- Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), CNRS UMR 8182, Université Paris-Saclay, Bâtiment 420, 91405 Orsay Cedex, France
| | - Vincent Gandon
- Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), CNRS UMR 8182, Université Paris-Saclay, Bâtiment 420, 91405 Orsay Cedex, France.,Laboratoire de Chimie Moléculaire (LCM), CNRS UMR 9168, Ecole Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91128 Palaiseau Cedex, France
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9
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Desrosiers V, Garcia CZ, Fontaine FG. Boron Recycling in the Metal-Free Transfer C–H Borylation of Terminal Alkynes and Heteroarenes. ACS Catal 2020. [DOI: 10.1021/acscatal.0c02682] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vincent Desrosiers
- Département de Chimie, Université Laval, 1045 Avenue de la Médecine, Quebec City, Quebec G1V 0A6, Canada
| | | | - Frédéric-Georges Fontaine
- Département de Chimie, Université Laval, 1045 Avenue de la Médecine, Quebec City, Quebec G1V 0A6, Canada
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10
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Abstract
In contrast to previously reported borylative heterocyclization methods, a reaction here proceeds without air-free techniques to access synthetically useful borylated thiophenes, benzothiophenes, and isocoumarins. A comparison of stability/decomposition rates in air of several catecholboronic ester (Bcat) compounds derived from different heterocycle cores showed a strong dependence on the heterocycle structure. Lessons learned from this comparison were then harnessed for the development of borylative heterocyclization reactions under ambient-atmosphere conditions and with wet solvent. In contrast to literature reports suggesting general moisture sensitivity, a subset of Bcat products resulting from this technique were chromatography-stable and directly isolable, obviating the requirement for an extra synthetic transformation into more stable boron species, such as pinacolboronic esters (Bpin), for isolation. The isolated Bcat products were amenable to various downstream functionalization reactions, including reactions that were not accessible with their better-known Bpin counterparts, showing the complementarity of Bcat reaction partners and expanding their known chemistry. These results suggest the value of conceptual revisitation of substitution and solvent influence on stability and isolability of organo-Bcat compound classes and lay the groundwork for development of additional practical borylative methods in air.
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Affiliation(s)
- Chao Gao
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Shuichi Nakao
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Suzanne A Blum
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
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11
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Spokoyny AM, Chiu CW, Bosley BD, Schubert DM. “Mr. Boron”, an Inorganic Chemistry Icon, Turns 90. Inorg Chem 2019; 58:5369-5374. [DOI: 10.1021/acs.inorgchem.9b00913] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alexander M. Spokoyny
- Department of Chemistry and Biochemistry and California Nanosystems Institute, University of California, Los Angeles (UCLA), 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Ching-Wen Chiu
- Department of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Beth D. Bosley
- Boron Specialties LLC, 2301 Duss Avenue, Building 9, Ambridge, Pennsylvania 15003, United States
| | - David M. Schubert
- Chemistry Department, Metropolitan State University of Denver, P.O. Box 173362, Campus Box 52, Denver, Colorado 80217, United States
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12
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Schroeder S, Strauch C, Gaelings N, Niggemann M. Vinyl Triflimides-A Case of Assisted Vinyl Cation Formation. Angew Chem Int Ed Engl 2019; 58:5119-5123. [PMID: 30694004 DOI: 10.1002/anie.201810916] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/28/2018] [Indexed: 12/31/2022]
Abstract
A new concept for selectivity control in carbocation-driven reactions has been identified which allows for the chemo-, regio-, and stereoselective addition of nucleophiles to alkynes-assisted vinyl cation formation-enabled by a Li+ -based supramolecular framework. Mechanistic analysis of a model complex (Li2 NTf2 + ⋅3 H2 O) confirms that solely the formation of a complex between the incoming nucleophile and the transition state of the alkyne protonation is responsible for the resulting selective N addition to the vinyl cation. Into the bargain, a general, operationally simple synthetic procedure to previously inaccessible vinyl triflimides is provided.
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Affiliation(s)
- Sebastian Schroeder
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52072, Aachen, Germany
| | - Christina Strauch
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52072, Aachen, Germany
| | - Niklas Gaelings
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52072, Aachen, Germany
| | - Meike Niggemann
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52072, Aachen, Germany
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13
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Schroeder S, Strauch C, Gaelings N, Niggemann M. Vinyltriflimide – ein Fall von assistierter Vinylkationenbildung. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201810916] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Sebastian Schroeder
- Institute of Organic ChemistryRWTH Aachen Landoltweg 1 52072 Aachen Deutschland
| | - Christina Strauch
- Institute of Organic ChemistryRWTH Aachen Landoltweg 1 52072 Aachen Deutschland
| | - Niklas Gaelings
- Institute of Organic ChemistryRWTH Aachen Landoltweg 1 52072 Aachen Deutschland
| | - Meike Niggemann
- Institute of Organic ChemistryRWTH Aachen Landoltweg 1 52072 Aachen Deutschland
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15
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Liu W, Zeng R, Han Y, Wang Y, Tao H, Chen Y, Liu F, Liang Y. Computational and experimental investigation on the BCl3 promoted intramolecular amination of alkenes and alkynes. Org Biomol Chem 2019; 17:2776-2783. [DOI: 10.1039/c9ob00264b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The BCl3 promoted aminoboration of alkenes and alkynes was investigated both computationally and experimentally, leading to the discovery of a metal-free hydroamination of alkynes.
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Affiliation(s)
- Wei Liu
- State Key Laboratory of Coordination Chemistry
- Jiangsu Key Laboratory of Advanced Organic Materials
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
| | - Ruxin Zeng
- State Key Laboratory of Coordination Chemistry
- Jiangsu Key Laboratory of Advanced Organic Materials
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
| | - Yingbin Han
- State Key Laboratory of Coordination Chemistry
- Jiangsu Key Laboratory of Advanced Organic Materials
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
| | - Yajun Wang
- State Key Laboratory of Coordination Chemistry
- Jiangsu Key Laboratory of Advanced Organic Materials
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
| | - Huimin Tao
- State Key Laboratory of Coordination Chemistry
- Jiangsu Key Laboratory of Advanced Organic Materials
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
| | - Yu Chen
- State Key Laboratory of Coordination Chemistry
- Jiangsu Key Laboratory of Advanced Organic Materials
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
| | - Fang Liu
- College of Sciences
- Nanjing Agricultural University
- Nanjing 210095
- China
| | - Yong Liang
- State Key Laboratory of Coordination Chemistry
- Jiangsu Key Laboratory of Advanced Organic Materials
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
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16
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Bel Abed H, Blum SA. Transition-Metal-Free Synthesis of Borylated Thiophenes via Formal Thioboration. Org Lett 2018; 20:6673-6677. [DOI: 10.1021/acs.orglett.8b02727] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Hassen Bel Abed
- Department of Chemistry, University of California—Irvine, Irvine, California 92617-2025, United States
| | - Suzanne A. Blum
- Department of Chemistry, University of California—Irvine, Irvine, California 92617-2025, United States
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17
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Kita Y, Yata T, Nishimoto Y, Chiba K, Yasuda M. Selective oxymetalation of terminal alkynes via 6- endo cyclization: mechanistic investigation and application to the efficient synthesis of 4-substituted isocoumarins. Chem Sci 2018; 9:6041-6052. [PMID: 30079217 PMCID: PMC6053900 DOI: 10.1039/c8sc01537f] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 06/13/2018] [Indexed: 01/05/2023] Open
Abstract
The cyclization of heteroatom-containing alkynes with π acidic metal salts is an attractive method to prepare heterocycles because the starting materials are readily available and the organometallic compounds are useful synthetic intermediates. A new organometallic species in the heterocyclization provides an opportunity to synthesize heterocycles that are difficult to obtain. Herein, we describe a novel cyclic oxymetalation of 2-alkynylbenzoate with indium or gallium salts that proceeds with an unusual regioselectivity to give isocoumarins bearing a carbon-metal bond at the 4-position. This new type of metalated isocoumarin provided 3-unsubstituted isocoumarins that have seldom been investigated despite their important pharmacological properties. Indium and gallium salts showed high performance in the selective 6-endo cyclization of terminal alkynes while boron or other metals such as Al, Au, and Ag caused 5-exo cyclization or decomposition of terminal alkynes, respectively. The metalated isocoumarin and its reaction intermediate were unambiguously identified by X-ray crystallographic analysis. The theoretical calculation of potential energy profiles showed that oxyindation could proceed via 6-endo cyclization under thermodynamic control while previously reported oxyboration would give a 5-membered ring under kinetic control. The investigation of electrostatic potential maps suggested that the differences in the atomic characters of indium, boron and their ligands would contribute to such a regioselective switch. The metalated isocoumarins were applied to organic synthetic reactions. The halogenation of metalated isocoumarins proceeded to afford 4-halogenated isocoumarins bearing various functional groups. The palladium-catalyzed cross coupling of organometallic species with organic halides gave various 4-substituted isocoumarins. A formal total synthesis of oosponol, which exhibits strong antifungal activity, was accomplished.
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Affiliation(s)
- Yuji Kita
- Department of Applied Chemistry , Graduate School of Engineering , Osaka University , 2-1 Yamadaoka, Suita , Osaka 565-0871 , Japan .
| | - Tetsuji Yata
- Department of Applied Chemistry , Graduate School of Engineering , Osaka University , 2-1 Yamadaoka, Suita , Osaka 565-0871 , Japan .
| | - Yoshihiro Nishimoto
- Frontier Research Base for Global Young Researchers Center for Open Innovation Research and Education (COiRE) , Graduate School of Engineering , Osaka University , 2-1 Yamadaoka, Suita , Osaka 565-0871 , Japan .
| | - Kouji Chiba
- Material Science Division , MOLSIS Inc. , 1-28-38 Shinkawa, Chuo-ku , Tokyo 104-0033 , Japan
| | - Makoto Yasuda
- Department of Applied Chemistry , Graduate School of Engineering , Osaka University , 2-1 Yamadaoka, Suita , Osaka 565-0871 , Japan .
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18
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Tu KN, Gao C, Blum SA. An Oxyboration Route to a Single Regioisomer of Borylated Dihydrofurans and Isochromenes. J Org Chem 2018; 83:11204-11217. [DOI: 10.1021/acs.joc.8b01790] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Kim N. Tu
- Department of Chemistry, University of California, Irvine, Irvine, California 92697−2025, United States
| | - Chao Gao
- Department of Chemistry, University of California, Irvine, Irvine, California 92697−2025, United States
| | - Suzanne A. Blum
- Department of Chemistry, University of California, Irvine, Irvine, California 92697−2025, United States
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19
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Tanaka S, Saito Y, Yamamoto T, Hattori T. Electrophilic Borylation of Terminal Alkenes with BBr 3/2,6-Disubstituted Pyridines. Org Lett 2018. [PMID: 29527895 DOI: 10.1021/acs.orglett.8b00335] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A variety of terminal alkenes, as well as heteroaromatic compounds, are borylated by the combined use of BBr3/2,6-dichloropyridine (B3) or BBr3/2,6-lutidine (B5). α,α-Diarylalkenes prefer the former reagent combination, while other alkenes prefer the latter. Mechanistic considerations strongly suggest that the former and latter reactions proceed through electrophilic substitution reactions with BBr3 and [BBr2·B5]+BBr4-, respectively.
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Affiliation(s)
- Shinya Tanaka
- Department of Biomolecular Engineering, Graduate School of Engineering , Tohoku University , 6-6-11 Aramaki-Aoba , Aoba-ku , Sendai 980-8579 , Japan
| | - Yuki Saito
- Department of Biomolecular Engineering, Graduate School of Engineering , Tohoku University , 6-6-11 Aramaki-Aoba , Aoba-ku , Sendai 980-8579 , Japan
| | - Takaya Yamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering , Tohoku University , 6-6-11 Aramaki-Aoba , Aoba-ku , Sendai 980-8579 , Japan
| | - Tetsutaro Hattori
- Department of Biomolecular Engineering, Graduate School of Engineering , Tohoku University , 6-6-11 Aramaki-Aoba , Aoba-ku , Sendai 980-8579 , Japan
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20
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Issaian A, Tu KN, Blum SA. Boron-Heteroatom Addition Reactions via Borylative Heterocyclization: Oxyboration, Aminoboration, and Thioboration. Acc Chem Res 2017; 50:2598-2609. [PMID: 28933550 DOI: 10.1021/acs.accounts.7b00365] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Organoboron compounds and heterocycles are powerful building blocks and precursors for organic synthesis, including for drug discovery and agrochemical and material synthesis. The common strategy for the synthesis of borylated heterocycles involves two separate synthetic steps: first, synthesis of the heterocyclic core, and second, borylation of the core through established methods such as transition-metal-catalyzed C-H or C-X activation/borylation or lithiation/borylation. In this Account, we describe our laboratory's development of borylative heterocyclization reactions that access the heterocyclic core and install boron in one synthetic step. These methods provide complementary bond disconnections, regiochemistry, and functional-group compatibility to current methods. We describe our methods with two categories: a direct borylation method that refers to addition reactions starting from a preformed B-element σ bond, which is essential in the mechanistic route to product formation, and a formal borylation method that refers to addition reactions that do not require formation of a B-element bond but instead proceed through carbon-carbon π-bond activation by an electrophilic boron source followed by dealkylation or deacylation. Through electrophilic activation of the alkyne rather than activation of the B-element bond, formal borylation provides a complementary strategy toward neutral organoboron reagents. We first studied direct oxyboration toward the formation of borylated benzofurans, where a preformed boron-oxygen σ bond is added across an alkyne activated by a carbophilic gold catalyst. We describe detailed mechanistic and kinetic studies of this class of reactions. Application of the knowledge gained from these studies aided in the future development of additional direct borylation reactions involving boron-nitrogen and boron-oxygen σ bonds to form borylared indoles and isoxazoles, respectively. Formal addition of boron/oxygen equivalents to effect oxyboration to form borylated lactones from o-alkynyl esters is then described. This class of reactions takes advantage of bifunctional ClBcat as a carbophilic carbon-carbon π-bond activator and eventual dealkylating agent. We describe our motivation in developing this new class of catalyst-free borylation reactions and subsequently applying the formal borylation strategy to the thioboration of o-alkynylthioanisole substrates to form borylated benzothiophenes. We then proceed to describe our investigations into the details of the mechanism of the formal thioboration reaction. These collaborative mechanistic studies included experimental and computational findings that elucidated the rate-determining step and intermediates of the reaction. These studies further compared different boron sources as electrophiles, including those used in other known reactions, providing fundamental knowledge about the capabilities of commercially available boron reagents toward borylative heterocyclization. Our findings provide guiding principles for reaction design and information leading toward the design of a diverse set of boron-heteroatom addition reactions and their formal equivalents that proceed through borylative heterocyclization.
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Affiliation(s)
- Adena Issaian
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Kim N. Tu
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Suzanne A. Blum
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
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