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Paparakis A, Turnell-Ritson RC, Sapsford JS, Ashley AE, Hulla M. Tin-catalyzed reductive coupling of amines with CO 2 and H 2. Catal Sci Technol 2023. [DOI: 10.1039/d2cy01659a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Tin-based FLPs catalyze reductive coupling reactions of amines with CO2 and H2. Water produced by the reaction is well tolerated and TONs up to 300 can be achieved.
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Affiliation(s)
- Alexandros Paparakis
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Prague 128 00, Czech Republic
| | | | - Joshua S. Sapsford
- Department of Chemistry, White City Campus, Imperial College London, London W12 0BZ, UK
| | - Andrew E. Ashley
- Department of Chemistry, White City Campus, Imperial College London, London W12 0BZ, UK
| | - Martin Hulla
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Prague 128 00, Czech Republic
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2
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Sapsford JS, Csókás D, Turnell-Ritson RC, Parkin LA, Crawford AD, Pápai I, Ashley AE. Transition Metal-Free Direct Hydrogenation of Esters via a Frustrated Lewis Pair. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01940] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
| | - Dániel Csókás
- Research Center for Natural Sciences, Institute of Organic Chemistry, Budapest H-1117, Hungary
| | | | - Liam A. Parkin
- Molecular Sciences Research Hub, Imperial College, London W12 0BZ, U.K
| | | | - Imre Pápai
- Research Center for Natural Sciences, Institute of Organic Chemistry, Budapest H-1117, Hungary
| | - Andrew E. Ashley
- Molecular Sciences Research Hub, Imperial College, London W12 0BZ, U.K
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3
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Sapsford JS, Csókás D, Scott DJ, Turnell-Ritson RC, Piascik AD, Pápai I, Ashley AE. Establishing the Role of Triflate Anions in H 2 Activation by a Cationic Triorganotin(IV) Lewis Acid. ACS Catal 2020; 10:7573-7583. [PMID: 32905389 PMCID: PMC7469243 DOI: 10.1021/acscatal.0c02023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/05/2020] [Indexed: 12/13/2022]
Abstract
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Cationic
Lewis acids (LAs) are gaining interest as targets for
frustrated Lewis pair (FLP)-mediated catalysis. Unlike neutral boranes,
which are the most prevalent LAs for FLP hydrogenations, the Lewis
acidity of cations can be tuned through modulation of the counteranion;
however, detailed studies on such anion effects are currently lacking
in the literature. Herein, we present experimental and computational
studies which probe the mechanism of H2 activation using iPr3SnOTf (1-OTf) in conjunction
with a coordinating (quinuclidine; qui) and noncoordinating (2,4,6-collidine;
col) base and compare its reactivity with {iPr3Sn·base}{Al[OC(CF3)3]4} (base = qui/col) systems which lack a coordinating anion to investigate
the active species responsible for H2 activation and hence
resolve any mechanistic roles for OTf– in the iPr3SnOTf-mediated pathway.
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Affiliation(s)
- Joshua S. Sapsford
- Molecular Sciences Research Hub, Imperial College, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
| | - Dániel Csókás
- Institute of Organic Chemistry, Research Center for Natural Sciences, Magyar tudósok körútja 2, Budapest H-1117, Hungary
| | - Daniel J. Scott
- Institute of Inorganic Chemistry, University of Regensburg, Universitätsstraße 31, Regensburg 93051, Germany
| | - Roland C. Turnell-Ritson
- Molecular Sciences Research Hub, Imperial College, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
| | - Adam D. Piascik
- Molecular Sciences Research Hub, Imperial College, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
| | - Imre Pápai
- Institute of Organic Chemistry, Research Center for Natural Sciences, Magyar tudósok körútja 2, Budapest H-1117, Hungary
| | - Andrew E. Ashley
- Molecular Sciences Research Hub, Imperial College, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
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Bennett EL, Lawrence EJ, Blagg RJ, Mullen AS, MacMillan F, Ehlers AW, Scott DJ, Sapsford JS, Ashley AE, Wildgoose GG, Slootweg JC. A New Mode of Chemical Reactivity for Metal-Free Hydrogen Activation by Lewis Acidic Boranes. Angew Chem Int Ed Engl 2019; 58:8362-8366. [PMID: 30968535 PMCID: PMC6594078 DOI: 10.1002/anie.201900861] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 04/09/2019] [Indexed: 12/13/2022]
Abstract
We herein explore whether tris(aryl)borane Lewis acids are capable of cleaving H2 outside of the usual Lewis acid/base chemistry described by the concept of frustrated Lewis pairs (FLPs). Instead of a Lewis base we use a chemical reductant to generate stable radical anions of two highly hindered boranes: tris(3,5-dinitromesityl)borane and tris(mesityl)borane. NMR spectroscopic characterization reveals that the corresponding borane radical anions activate (cleave) dihydrogen, whilst EPR spectroscopic characterization, supported by computational analysis, reveals the intermediates along the hydrogen activation pathway. This radical-based, redox pathway involves the homolytic cleavage of H2 , in contrast to conventional models of FLP chemistry, which invoke a heterolytic cleavage pathway. This represents a new mode of chemical reactivity for hydrogen activation by borane Lewis acids.
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Affiliation(s)
- Elliot L. Bennett
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Elliot J. Lawrence
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Robin J. Blagg
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Anna S. Mullen
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Fraser MacMillan
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Andreas W. Ehlers
- Van 't Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 904, PO Box 941571090 GDAmsterdamThe Netherlands
- Department of Chemistry, Science FacultyUniversity of JohannesburgPO Box 254, Auckland ParkJohannesburgSouth Africa
| | - Daniel J. Scott
- Molecular Sciences Research HubImperial College White City Campus80 Wood LaneLondonW12 0BZUK
| | - Joshua S. Sapsford
- Molecular Sciences Research HubImperial College White City Campus80 Wood LaneLondonW12 0BZUK
| | - Andrew E. Ashley
- Molecular Sciences Research HubImperial College White City Campus80 Wood LaneLondonW12 0BZUK
| | - Gregory G. Wildgoose
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - J. Chris Slootweg
- Van 't Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 904, PO Box 941571090 GDAmsterdamThe Netherlands
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5
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Bennett EL, Lawrence EJ, Blagg RJ, Mullen AS, MacMillan F, Ehlers AW, Scott DJ, Sapsford JS, Ashley AE, Wildgoose GG, Slootweg JC. A New Mode of Chemical Reactivity for Metal‐Free Hydrogen Activation by Lewis Acidic Boranes. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201900861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Elliot L. Bennett
- School of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Elliot J. Lawrence
- School of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Robin J. Blagg
- School of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Anna S. Mullen
- School of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Fraser MacMillan
- School of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Andreas W. Ehlers
- Van 't Hoff Institute for Molecular SciencesUniversity of Amsterdam Science Park 904, PO Box 94157 1090 GD Amsterdam The Netherlands
- Department of Chemistry, Science FacultyUniversity of Johannesburg PO Box 254, Auckland Park Johannesburg South Africa
| | - Daniel J. Scott
- Molecular Sciences Research HubImperial College White City Campus 80 Wood Lane London W12 0BZ UK
| | - Joshua S. Sapsford
- Molecular Sciences Research HubImperial College White City Campus 80 Wood Lane London W12 0BZ UK
| | - Andrew E. Ashley
- Molecular Sciences Research HubImperial College White City Campus 80 Wood Lane London W12 0BZ UK
| | - Gregory G. Wildgoose
- School of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - J. Chris Slootweg
- Van 't Hoff Institute for Molecular SciencesUniversity of Amsterdam Science Park 904, PO Box 94157 1090 GD Amsterdam The Netherlands
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Sapsford JS, Gates SJ, Doyle LR, Taylor RA, Díez-González S, Ashley AE. Cp*Fe(Me2PCH2CH2PMe2)(CHO): Hydride shuttle reactivity of a thermally stable formyl complex. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.01.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Turnell-Ritson RC, Sapsford JS, Cooper RT, Lee SS, Földes T, Hunt PA, Pápai I, Ashley AE. Base-induced reversible H 2 addition to a single Sn(ii) centre. Chem Sci 2018; 9:8716-8722. [PMID: 30627391 PMCID: PMC6289099 DOI: 10.1039/c8sc03110j] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/17/2018] [Indexed: 12/02/2022] Open
Abstract
A range of amines catalyse the oxidative addition (OA) of H2 to [(Me3Si)2CH]2Sn (1), forming [(Me3Si)2CH]2SnH2 (2). Experimental and computational studies point to 'frustrated Lewis pair' mechanisms in which 1 acts as a Lewis acid and involve unusual late transition states; this is supported by the observation of a kinetic isotope effect for Et3N. When DBU is used the energetics of H2 activation are altered, allowing an equilibrium between 1, 2 and adduct [1·DBU] to be established, thus demonstrating reversible oxidative addition/reductive elimination (RE) of H2 at a single main group centre.
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Affiliation(s)
| | - Joshua S Sapsford
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - Robert T Cooper
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - Stella S Lee
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - Tamás Földes
- Research Center for Natural Sciences , Hungarian Academy of Sciences , Magyar tudósok körútja 2 , H-1117 Budapest , Hungary .
| | - Patricia A Hunt
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - Imre Pápai
- Research Center for Natural Sciences , Hungarian Academy of Sciences , Magyar tudósok körútja 2 , H-1117 Budapest , Hungary .
| | - Andrew E Ashley
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
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Sapsford JS, Scott DJ, Allcock NJ, Fuchter MJ, Tighe CJ, Ashley AE. Direct Reductive Amination of Carbonyl Compounds Catalyzed by a Moisture Tolerant Tin(IV) Lewis Acid. Adv Synth Catal 2018; 360:1066-1071. [PMID: 29706853 PMCID: PMC5901005 DOI: 10.1002/adsc.201701418] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 12/14/2017] [Indexed: 12/03/2022]
Abstract
Despite the ever-broadening applications of main-group 'frustrated Lewis pair' (FLP) chemistry to both new and established reactions, their typical intolerance of water, especially at elevated temperatures (>100 °C), represents a key barrier to their mainstream adoption. Herein we report that FLPs based on the Lewis acid iPr3SnOTf are moisture tolerant in the presence of moderately strong nitrogenous bases, even under high temperature regimes, allowing them to operate as simple and effective catalysts for the reductive amination of organic carbonyls, including for challenging bulky amine and carbonyl substrate partners.
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Affiliation(s)
| | - Daniel J. Scott
- Department of ChemistryImperial College LondonLondonSW7 2AZUK
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Cooper RT, Sapsford JS, Turnell-Ritson RC, Hyon DH, White AJP, Ashley AE. Hydrogen activation using a novel tribenzyltin Lewis acid. Philos Trans A Math Phys Eng Sci 2017; 375:rsta.2017.0008. [PMID: 28739966 PMCID: PMC5540841 DOI: 10.1098/rsta.2017.0008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 04/11/2017] [Indexed: 06/07/2023]
Abstract
Over the last decade there has been an explosion in the reactivity and applications of frustrated Lewis pair (FLP) chemistry. Despite this, the Lewis acids (LAs) in these transformations are often boranes, with heavier p-block elements receiving surprisingly little attention. The novel LA Bn3SnOTf (1) has been synthesized from simple, inexpensive starting materials and has been spectroscopically and structurally characterized. Subtle modulation of the electronics at the tin centre has led to an increase in its Lewis acidity in comparison with previously reported R3SnOTf LAs, and has facilitated low temperature hydrogen activation and imine hydrogenation. Deactivation pathways of the R3Sn+ LA core have also been investigated.This article is part of the themed issue 'Frustrated Lewis pair chemistry'.
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Affiliation(s)
- Robert T Cooper
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Joshua S Sapsford
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Roland C Turnell-Ritson
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Dong-Hun Hyon
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Andrew J P White
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Andrew E Ashley
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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Scott DJ, Phillips NA, Sapsford JS, Deacy AC, Fuchter MJ, Ashley AE. Versatile Catalytic Hydrogenation Using A Simple Tin(IV) Lewis Acid. Angew Chem Int Ed Engl 2016; 55:14738-14742. [PMID: 27774711 PMCID: PMC5129554 DOI: 10.1002/anie.201606639] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/05/2016] [Indexed: 12/19/2022]
Abstract
Despite the rapid development of frustrated Lewis pair (FLP) chemistry over the last ten years, its application in catalytic hydrogenations remains dependent on a narrow family of structurally similar early main-group Lewis acids (LAs), inevitably placing limitations on reactivity, sensitivity and substrate scope. Herein we describe the FLP-mediated H2 activation and catalytic hydrogenation activity of the alternative LA iPr3 SnOTf, which acts as a surrogate for the trialkylstannylium ion iPr3 Sn+ , and is rapidly and easily prepared from simple, inexpensive starting materials. This highly thermally robust LA is found to be competent in the hydrogenation of a number of different unsaturated functional groups (which is unique to date for main-group FLP LAs not based on boron), and also displays a remarkable tolerance to moisture.
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Affiliation(s)
- Daniel J. Scott
- Department of ChemistryImperial College LondonLondonSW7 2AZUK
| | | | | | - Arron C. Deacy
- Department of ChemistryImperial College LondonLondonSW7 2AZUK
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Scott DJ, Phillips NA, Sapsford JS, Deacy AC, Fuchter MJ, Ashley AE. Versatile Catalytic Hydrogenation Using A Simple Tin(IV) Lewis Acid. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201606639] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Daniel J. Scott
- Department of Chemistry; Imperial College London; London SW7 2AZ UK
| | | | | | - Arron C. Deacy
- Department of Chemistry; Imperial College London; London SW7 2AZ UK
| | | | - Andrew E. Ashley
- Department of Chemistry; Imperial College London; London SW7 2AZ UK
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