1
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Clarke J, Seo Y, Gagné MR, Bender TA. Achieving Site-Selective C–O Bond Reduction for High-Value Cellulosic Valorization. ACS Catal 2022. [DOI: 10.1021/acscatal.2c04768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Joshua Clarke
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Youngran Seo
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Michel R. Gagné
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Trandon A. Bender
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia 23529, United States
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2
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Lowe JM, Seo Y, Clarke JJ, Gagné MR. Precyclization Conformer Profiles of -SiR 3+- and -Bcat +-Activated Linear Si-Protected Hexitols Explain Condensative Cyclization Selectivities. J Org Chem 2022; 87:12065-12071. [PMID: 36053236 DOI: 10.1021/acs.joc.2c01151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The condensative cyclization of sp3 C-O bonds in per-silylated hexitols is investigated by computation. Conformer searches using the Monte Carlo algorithm, followed by successively higher levels of theory (MMFF, PM3, and B3LYP), of -SiR3+- and -Bcat+-activated substrates lead to structures primed for intramolecular chemistry. Silane activation features O4 to C1 attack, while borane activation suggests boronium ions that activate O5 to C2 reactivity. This, in conjunction with Boltzmann population analysis, parallels reported reactivity for sorbitol, mannitol, and galactitol. Calculations using the meta-hybrid M06-2X functional additionally provide free-energy profiles for each cyclization event. In most of the cases presented, precyclization conformers that position a nucleophilic oxygen less than 3.0 Å from the C-O leaving group correlate to efficient experimental reactivities. Two examples of galactitol containing bridging silyl groups are analyzed computationally, and the experimental outcomes match predictions. The computational regime presented is a step closer to providing predictive power for the reduction of per-functionalized molecules.
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Affiliation(s)
- Jared M Lowe
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Youngran Seo
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Joshua J Clarke
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Michel R Gagné
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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3
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Ríos P, Rodríguez A, Conejero S. Activation of Si-H and B-H bonds by Lewis acidic transition metals and p-block elements: same, but different. Chem Sci 2022; 13:7392-7418. [PMID: 35872827 PMCID: PMC9241980 DOI: 10.1039/d2sc02324e] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 05/18/2022] [Indexed: 01/01/2023] Open
Abstract
In this Perspective we discuss the ability of transition metal complexes to activate and cleave the Si-H and B-H bonds of hydrosilanes and hydroboranes (tri- and tetra-coordinated) in an electrophilic manner, avoiding the need for the metal centre to undergo two-electron processes (oxidative addition/reductive elimination). A formal polarization of E-H bonds (E = Si, B) upon their coordination to the metal centre to form σ-EH complexes (with coordination modes η1 or η2) favors this type of bond activation that can lead to reactivities involving the formation of transient silylium and borenium/boronium cations similar to those proposed in silylation and borylation processes catalysed by boron and aluminium Lewis acids. We compare the reactivity of transition metal complexes and boron/aluminium Lewis acids through a series of catalytic reactions in which pieces of evidence suggest mechanisms involving electrophilic reaction pathways.
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Affiliation(s)
- Pablo Ríos
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica CSIC and Universidad de Sevilla, Centro de Innovación en Química Avanzada (ORFEO-CINQA) C/Américo Vespucio 49 41092 Sevilla Spain
| | - Amor Rodríguez
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica CSIC and Universidad de Sevilla, Centro de Innovación en Química Avanzada (ORFEO-CINQA) C/Américo Vespucio 49 41092 Sevilla Spain
| | - Salvador Conejero
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica CSIC and Universidad de Sevilla, Centro de Innovación en Química Avanzada (ORFEO-CINQA) C/Américo Vespucio 49 41092 Sevilla Spain
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4
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Clarke JJ, Basemann K, Romano N, Lee SJ, Gagné MR. Borane- and Silylium-Catalyzed Difunctionalization of Carbohydrates: 3,6-Anhydrosugar Enabled 1,6-Site Selectivity. Org Lett 2022; 24:4135-4139. [PMID: 35653692 DOI: 10.1021/acs.orglett.2c01243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel diastereoselective, Lewis acid catalyzed 1,6-difunctionalization of galactose and mannose derivatives has been developed in one pot, via sequential nucleophile additions. Our studies point to the formation of a 3,6-anhydrosugar intermediate as key to the 1,6-site-selectivity. Starting material-specific reactivity occurs when competitive ring-opening C-O cleavage is possible, owed to basicity and stereoelectronic stabilization differences. Lastly, Mayr nucleophilicity parameter values helped predict which reaction conditions would be most suitable for specific nucleophiles.
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Affiliation(s)
- Joshua J Clarke
- Caudill Laboratories, Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Kevin Basemann
- Caudill Laboratories, Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Neyen Romano
- Caudill Laboratories, Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Stephen J Lee
- U.S. Army Research Office, P.O. Box 12211, Research Triangle Park, North Carolina 27709, United States
| | - Michel R Gagné
- Caudill Laboratories, Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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5
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Starr HE, Gagné MR. Probing the Source of Enhanced Activity in Multiborylated Silsesquioxane Catalysts for C–O Bond Reduction. Organometallics 2022. [DOI: 10.1021/acs.organomet.1c00701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hannah E. Starr
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Michel R. Gagné
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
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6
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Suh CE, Carder HM, Wendlandt AE. Selective Transformations of Carbohydrates Inspired by Radical-Based Enzymatic Mechanisms. ACS Chem Biol 2021; 16:1814-1828. [PMID: 33988380 DOI: 10.1021/acschembio.1c00190] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Enzymes are a longstanding source of inspiration for synthetic reaction development. However, enzymatic reactivity and selectivity are frequently untenable in a synthetic context, as the principles that govern control in an enzymatic setting often do not translate to small molecule catalysis. Recent synthetic methods have revealed the viability of using small molecule catalysts to promote highly selective radical-mediated transformations of minimally protected sugar substrates. These transformations share conceptual similarities with radical SAM enzymes found in microbial carbohydrate biosynthesis and present opportunities for synthetic chemists to access microbial and unnatural carbohydrate building blocks without the need for protecting groups or lengthy synthetic sequences. Here, we highlight strategies through which radical reaction pathways can enable the site-, regio-, and diastereoselective transformation of minimally protected carbohydrates in both synthetic and enzymatic systems.
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Affiliation(s)
- Carolyn E. Suh
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Hayden M. Carder
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alison E. Wendlandt
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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7
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Seo Y, Lowe JM, Romano N, Gagné MR. Switching between X-Pyrano-, X-Furano-, and Anhydro- X-pyranoside Synthesis (X = C, N) under Lewis acid Catalyzed Conditions. Org Lett 2021; 23:5636-5640. [PMID: 34259527 DOI: 10.1021/acs.orglett.1c01713] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A variety of C-glycosides can be obtained from the fluoroarylborane (B(C6F5)3) or silylium (R3Si+) catalyzed functionalization of 1-MeO- and per-TMS-sugars with TMS-X reagents. A one-step functionalization with a change as simple as the addition order and/or Lewis acid and TMS-X enables one to afford chiral synthons that are common (C-pyranosides), have few viable synthetic methods (C-furanosides), or are virtually unknown (anhydro-C-pyranosides), which mechanistically arise from whether a direct substitution, isomerization/substitution, or substitution/isomerization occurs, respectively.
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Affiliation(s)
- Youngran Seo
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jared M Lowe
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Neyen Romano
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Michel R Gagné
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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8
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Jones CAH, Schley ND. Selective demethylation of O-aryl glycosides by iridium-catalyzed hydrosilylation. Chem Commun (Camb) 2021; 57:5953-5956. [PMID: 34019603 DOI: 10.1039/d1cc00496d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The cleavage of alkyl ethers by hydrosilylation is a powerful synthetic tool for the generation of silyl ethers. Previous attempts to apply this transformation to carbohydrate derivatives have been constrained by poor selectivity and preferential reduction of the anomeric position. O-Aryl glycosides are found to be stable under iridium- and borane-catalyzed hydrosilylation conditions, allowing for alkyl ether cleavage without loss of anomeric functionality. A cationic bis(phosphine)iridium complex catalyzes the selective 3-demethylation of a variety of 2,3,4-tri-O-methyl pyranoses, offering a unique approach to 3-hydroxy or 3-acetyl 2,4-di-O-methylpyranoses.
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Affiliation(s)
- Caleb A H Jones
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA.
| | - Nathan D Schley
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA.
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9
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Stoian C, Olaru M, Cucuiet TA, Kegyes KT, Sava A, Timoshkin AY, Raţ CI, Beckmann J. Bulky Polyfluorinated Terphenyldiphenylboranes: Water Tolerant Lewis Acids. Chemistry 2021; 27:4327-4331. [PMID: 33368648 PMCID: PMC7986919 DOI: 10.1002/chem.202005367] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Indexed: 11/23/2022]
Abstract
Protocols for the synthesis of the bulky polyfluorinated triarylboranes 2,6‐(C6F5)2C6F3B(C6F5)2 (1), 2,6‐(C6F5)2C6F3B[3,5‐(CF3)2C6H3] (2), 2,4,6‐(C6F5)3C6H2B(C6F5)2 (3), 2,4,6‐(C6F5)3C6H2B[3,5‐(CF3)2C6H3] (4) were developed. All boranes are water tolerant and according to the Gutmann‐Beckett method, 1–3 display Lewis acidities larger than that of the prominent B(C6F5)3.
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Affiliation(s)
- Corina Stoian
- Institut für Anorganische Chemie und Kristallographie, Universität Bremen, Leobener Straße 7, 28359, Bremen, Germany.,Department of Chemistry, Supramolecular Organic and Organometallic Chemistry Centre (SOOMCC), Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Arany János Steet 11, 400028, Cluj-Napoca, Romania
| | - Marian Olaru
- Institut für Anorganische Chemie und Kristallographie, Universität Bremen, Leobener Straße 7, 28359, Bremen, Germany
| | - Teodor A Cucuiet
- Department of Chemistry, Supramolecular Organic and Organometallic Chemistry Centre (SOOMCC), Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Arany János Steet 11, 400028, Cluj-Napoca, Romania
| | - Krisztina T Kegyes
- Department of Chemistry, Supramolecular Organic and Organometallic Chemistry Centre (SOOMCC), Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Arany János Steet 11, 400028, Cluj-Napoca, Romania
| | - Alexandru Sava
- Department of Chemistry, Supramolecular Organic and Organometallic Chemistry Centre (SOOMCC), Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Arany János Steet 11, 400028, Cluj-Napoca, Romania
| | - Alexey Y Timoshkin
- Institute of Chemistry, St. Petersburg State University, Universitetskaya emb. 7/9, 199034, St. Petersburg, Russia
| | - Ciprian I Raţ
- Department of Chemistry, Supramolecular Organic and Organometallic Chemistry Centre (SOOMCC), Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Arany János Steet 11, 400028, Cluj-Napoca, Romania
| | - Jens Beckmann
- Institut für Anorganische Chemie und Kristallographie, Universität Bremen, Leobener Straße 7, 28359, Bremen, Germany
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10
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Jiang H, Lu R, Luo X, Si X, Xu J, Lu F. Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals. Chemistry 2021; 27:1292-1296. [PMID: 32929787 DOI: 10.1002/chem.202003776] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Indexed: 01/05/2023]
Abstract
With the growing demand for sustainability and reducing CO2 footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.
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Affiliation(s)
- Huifang Jiang
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Dalian, 116023, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Rui Lu
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Dalian, 116023, P. R. China
| | - Xiaolin Luo
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Dalian, 116023, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Xiaoqin Si
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Dalian, 116023, P. R. China
| | - Jie Xu
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Dalian, 116023, P. R. China
| | - Fang Lu
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Dalian, 116023, P. R. China
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11
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Holmstedt S, George L, Koivuporras A, Valkonen A, Candeias NR. Deoxygenative Divergent Synthesis: En Route to Quinic Acid Chirons. Org Lett 2020; 22:8370-8375. [PMID: 33002357 DOI: 10.1021/acs.orglett.0c02995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The installation of vicinal mesylate and silyl ether groups in a quinic acid derivative generates a system prone for stereoselective borane-catalyzed hydrosilylation through a siloxonium intermediate. The diversification of the reaction conditions allowed the construction of different defunctionalized fragments foreseen as useful synthetic fragments. The selectivity of the hydrosilylation was rationalized on the basis of deuteration experiments and computational studies.
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Affiliation(s)
- Suvi Holmstedt
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33101 Tampere, Finland
| | - Lijo George
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33101 Tampere, Finland
| | - Alisa Koivuporras
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33101 Tampere, Finland
| | - Arto Valkonen
- Department of Chemistry, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
| | - Nuno R Candeias
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33101 Tampere, Finland.,LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
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12
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Bentley JN, Elgadi SA, Gaffen JR, Demay-Drouhard P, Baumgartner T, Caputo CB. Fluorescent Lewis Adducts: A Practical Guide to Relative Lewis Acidity. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00389] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jordan N. Bentley
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Seja A. Elgadi
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Joshua R. Gaffen
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Paul Demay-Drouhard
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Thomas Baumgartner
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Christopher B. Caputo
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
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13
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Lowe JM, Bowers BE, Seo Y, Gagné MR. Modulating Electrostatic Interactions in Ion Pair Intermediates To Alter Site Selectivity in the C−O Deoxygenation of Sugars. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202007415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Jared M. Lowe
- Department of Chemistry University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA
| | - Bekah E. Bowers
- Department of Chemistry University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA
| | - Youngran Seo
- Department of Chemistry University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA
| | - Michel R. Gagné
- Department of Chemistry University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA
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14
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Fang H, Oestreich M. Defunctionalisation catalysed by boron Lewis acids. Chem Sci 2020; 11:12604-12615. [PMID: 34094457 PMCID: PMC8163203 DOI: 10.1039/d0sc03712e] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 07/22/2020] [Indexed: 12/22/2022] Open
Abstract
Selective defunctionalisation of organic molecules to valuable intermediates is a fundamentally important transformation in organic synthesis. Despite the advances made in efficient and selective defunctionalisation using transition-metal catalysis, the cost, toxicity, and non-renewable properties limit its application in industrial manufacturing processes. In this regard, boron Lewis acid catalysis has emerged as a powerful tool for the cleavage of carbon-heteroatom bonds. The ground-breaking finding is that the strong boron Lewis acid B(C6F5)3 can activate Si-H bonds through η1 coordination, and this Lewis adduct is a key intermediate that enables various reduction processes. This system can be tuned by variation of the electronic and structural properties of the borane catalyst, and together with different hydride sources high chemoselectivity can be achieved. This Perspective provides a comprehensive summary of various defunctionalisation reactions such as deoxygenation, decarbonylation, desulfurisation, deamination, and dehalogenation, all of which catalysed by boron Lewis acids.
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Affiliation(s)
- Huaquan Fang
- Institut für Chemie, Technische Universität Berlin Strasse des 17. Juni 115 10623 Berlin Germany
| | - Martin Oestreich
- Institut für Chemie, Technische Universität Berlin Strasse des 17. Juni 115 10623 Berlin Germany
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15
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Lowe JM, Bowers BE, Seo Y, Gagné MR. Modulating Electrostatic Interactions in Ion Pair Intermediates To Alter Site Selectivity in the C-O Deoxygenation of Sugars. Angew Chem Int Ed Engl 2020; 59:17297-17300. [PMID: 32521102 DOI: 10.1002/anie.202007415] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Indexed: 11/09/2022]
Abstract
Controlling which products one can access from the predefined biomass-derived sugars is challenging. Changing from CH2 Cl2 to the greener alternative toluene alters which C-O bonds in a sugar are cleaved by the tris(pentafluorophenyl)borane/HSiR3 catalyst system. This increases the diversity of high-value products that can be obtained through one-step, high-yielding, catalytic transformations of the mono-, di-, and oligosaccharides. Computational methods helped identify this non-intuitive outcome in low dielectric solvents to non-isotropic electrostatic enhancements in the key ion pair intermediates, which influence the reaction coordinate in the reactivity-/selectivity-determining step. Molecular-level models for these effects have far-reaching consequences in stereoselective ion pair catalysis.
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Affiliation(s)
- Jared M Lowe
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Bekah E Bowers
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Youngran Seo
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Michel R Gagné
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
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16
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Fast CD, Jones CAH, Schley ND. Selectivity and Mechanism of Iridium-Catalyzed Cyclohexyl Methyl Ether Cleavage. ACS Catal 2020. [DOI: 10.1021/acscatal.0c01718] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Caleb D. Fast
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 27235 United States
| | - Caleb A. H. Jones
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 27235 United States
| | - Nathan D. Schley
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 27235 United States
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17
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Sandeep, Venugopalan P, Kumar A. Metal Free, Direct and Selective Deoxygenation of α-Hydroxy Carbonyl Compounds: Access to α,α-Diaryl Carbonyl Compounds. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000142] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Sandeep
- Department of Applied Sciences; University Institute of Engineering and Technology; Panjab University; 160014 Chandigarh India
- Department of Chemistry; University Institute of Engineering and Technology; Panjab University; 160014 Chandigarh India
| | - Paloth Venugopalan
- Department of Chemistry; University Institute of Engineering and Technology; Panjab University; 160014 Chandigarh India
| | - Anil Kumar
- Department of Applied Sciences; University Institute of Engineering and Technology; Panjab University; 160014 Chandigarh India
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18
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Seo Y, Gudz A, Lowe JM, Gagné MR. Selective deoxygenation of gibberellic acid with fluoroarylborane catalysts. Tetrahedron 2019; 75. [PMID: 32523234 DOI: 10.1016/j.tet.2019.130712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Reductive late-stage functionalization of gibberellic acid is reported using three fluoroarylborane Lewis acids; (B(C6F5)3, B(3,5-C6H3(CF3)2), and B(2,4,6-C6H2F3)3) in combination with a tertiary silane and a borane (HBCat) reductant. In each case, C-O bond activation occurs, and different products are obtained depending on the reductant and catalyst employed.
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Affiliation(s)
- Youngran Seo
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Anton Gudz
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Jared M Lowe
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Michel R Gagné
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
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