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Tsutsui Y, Tanaka D, Manabe Y, Ikinaga Y, Yano K, Fukase K, Konishi A, Yasuda M. Synthesis of Cage‐Shaped Borates Bearing Pyrenylmethyl Groups: Efficient Lewis Acid Catalyst for Photoactivated Glycosylations Driven by Intramolecular Excimer Formation. Chemistry 2022; 28:e202202284. [DOI: 10.1002/chem.202202284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Yuya Tsutsui
- Department of Applied Chemistry Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
| | - Daiki Tanaka
- Department of Applied Chemistry Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
| | - Yoshiyuki Manabe
- Department of Chemistry Graduate School of Science Osaka University 1-1 Machikaneyama Toyonaka Osaka 560-0043 Japan
- Forefront Research Center Osaka University 1-1 Machikaneyama Toyonaka Osaka 560-0043 Japan
| | - Yuka Ikinaga
- Department of Chemistry Graduate School of Science Osaka University 1-1 Machikaneyama Toyonaka Osaka 560-0043 Japan
| | - Kumpei Yano
- Department of Chemistry Graduate School of Science Osaka University 1-1 Machikaneyama Toyonaka Osaka 560-0043 Japan
| | - Koichi Fukase
- Department of Chemistry Graduate School of Science Osaka University 1-1 Machikaneyama Toyonaka Osaka 560-0043 Japan
- Forefront Research Center Osaka University 1-1 Machikaneyama Toyonaka Osaka 560-0043 Japan
| | - Akihito Konishi
- Department of Applied Chemistry Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
- Innovative Catalysis Science Division Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI) Osaka University Suita Osaka 565-0871 Japan
- Center for Atomic and Molecular Technologies Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
| | - Makoto Yasuda
- Department of Applied Chemistry Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan
- Innovative Catalysis Science Division Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI) Osaka University Suita Osaka 565-0871 Japan
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2
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Beck AD, Haufe S, Waldvogel SR. Boron‐catalyzed electrochemical oxidative Si‐C bond formation. ChemElectroChem 2022. [DOI: 10.1002/celc.202200840] [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)
- Alexander D. Beck
- Johannes Gutenberg Universität Mainz: Johannes Gutenberg Universitat Mainz Department Chemie GERMANY
| | - Stefan Haufe
- Wacker Group: Wacker Chemie AG Consortium für Elektrochemie GERMANY
| | - Siegfried R Waldvogel
- Johannes Gutenberg-Universität Mainz Institut für Organische Chemie Duesbergweg 10-14 55128 Mainz GERMANY
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Mayer RJ, Hampel N, Ofial AR. Lewis Acidic Boranes, Lewis Bases, and Equilibrium Constants: A Reliable Scaffold for a Quantitative Lewis Acidity/Basicity Scale. Chemistry 2021; 27:4070-4080. [PMID: 33215760 PMCID: PMC7985883 DOI: 10.1002/chem.202003916] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Indexed: 12/15/2022]
Abstract
A quantitative Lewis acidity/basicity scale toward boron-centered Lewis acids has been developed based on a set of 90 experimental equilibrium constants for the reactions of triarylboranes with various O-, N-, S-, and P-centered Lewis bases in dichloromethane at 20 °C. Analysis with the linear free energy relationship log KB =LAB +LBB allows equilibrium constants, KB , to be calculated for any type of borane/Lewis base combination through the sum of two descriptors, one for Lewis acidity (LAB ) and one for Lewis basicity (LBB ). The resulting Lewis acidity/basicity scale is independent of fixed reference acids/bases and valid for various types of trivalent boron-centered Lewis acids. It is demonstrated that the newly developed Lewis acidity/basicity scale is easily extendable through linear relationships with quantum-chemically calculated or common physical-organic descriptors and known thermodynamic data (ΔHBF 3 ). Furthermore, this experimental platform can be utilized for the rational development of borane-catalyzed reactions.
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Affiliation(s)
- Robert J. Mayer
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MünchenGermany
| | - Nathalie Hampel
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MünchenGermany
| | - Armin R. Ofial
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MünchenGermany
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Krupski S, Kehr G, Daniliuc CG, Erker G. Cyclopropane formation under frustrated Lewis pair conditions. Chem Commun (Camb) 2016; 52:2695-7. [DOI: 10.1039/c5cc09585a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reaction of the –CH2OSiMe3 substituted allyldimesitylphosphane with HB(C6F5)2 resulted in a hydroboration/(C6F5)2BOSiMe3 elimination sequence to give the phosphinomethyl substituted cyclopropane derivative, probably via a phosphiranium type intermediate.
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Affiliation(s)
- Sergei Krupski
- Organisch-Chemisches Institut
- Universität Münster
- 48149 Münster
- Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut
- Universität Münster
- 48149 Münster
- Germany
| | | | - Gerhard Erker
- Organisch-Chemisches Institut
- Universität Münster
- 48149 Münster
- Germany
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5
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Yu J, Kehr G, Daniliuc CG, Erker G. Cooperative reaction chemistry derived from a borata-diene framework. Chem Commun (Camb) 2016; 52:1393-6. [DOI: 10.1039/c5cc07954c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A bifunctional frustrated BH−/B hydridoborate nucleophile/borane Lewis acid pair is prepared starting from a zwitterionic phoshonium borata-diene by a sequence of sequential protonation/hydride attachment, followed by hydroboration with Piers' borane [HB(C6F5)2]. The bifunctional product reduced carbon monoxide.
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Affiliation(s)
- Jiangang Yu
- Organisch-Chemisches Institut der Universität Münster
- 48149 Münster
- Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut der Universität Münster
- 48149 Münster
- Germany
| | | | - Gerhard Erker
- Organisch-Chemisches Institut der Universität Münster
- 48149 Münster
- Germany
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6
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Tussing S, Greb L, Tamke S, Schirmer B, Muhle-Goll C, Luy B, Paradies J. Autoinduced catalysis and inverse equilibrium isotope effect in the frustrated Lewis pair catalyzed hydrogenation of imines. Chemistry 2015; 21:8056-9. [PMID: 25877865 DOI: 10.1002/chem.201500805] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Indexed: 01/07/2023]
Abstract
The frustrated Lewis pair (FLP)-catalyzed hydrogenation and deuteration of N-benzylidene-tert-butylamine (2) was kinetically investigated by using the three boranes B(C6F5)3 (1), B(2,4,6-F3-C6H2)3 (4), and B(2,6-F2-C6H3)3 (5) and the free activation energies for the H2 activation by FLP were determined. Reactions catalyzed by the weaker Lewis acids 4 and 5 displayed autoinductive catalysis arising from a higher free activation energy (2 kcal mol(-1)) for the H2 activation by the imine compared to the amine. Surprisingly, the imine reduction using D2 proceeded with higher rates. This phenomenon is unprecedented for FLP and resulted from a primary inverse equilibrium isotope effect.
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Affiliation(s)
- Sebastian Tussing
- Institute of Organic Chemistry, University of Paderborn, Warburger Straße 100, 33098 Paderborn (Germany)
| | - Lutz Greb
- Institute of Organic Chemistry, University of Paderborn, Warburger Straße 100, 33098 Paderborn (Germany)
| | - Sergej Tamke
- Institute of Organic Chemistry, University of Paderborn, Warburger Straße 100, 33098 Paderborn (Germany)
| | - Birgitta Schirmer
- Center for Multiscale Theory and Computation (CMTC) und Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster (Germany)
| | - Claudia Muhle-Goll
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe (Germany)
| | - Burkhard Luy
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe (Germany).,Department Magnetic Resonance of the Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 (Germany)
| | - Jan Paradies
- Institute of Organic Chemistry, University of Paderborn, Warburger Straße 100, 33098 Paderborn (Germany).
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Manor BC, Ringenberg MR, Rauchfuss TB. Borane-protected cyanides as surrogates of H-bonded cyanides in [FeFe]-hydrogenase active site models. Inorg Chem 2014; 53:7241-7. [PMID: 24992155 PMCID: PMC4364604 DOI: 10.1021/ic500470z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Triarylborane Lewis acids bind [Fe2(pdt)(CO)4(CN)2](2-) [1](2-) (pdt(2-) = 1,3-propanedithiolate) and [Fe2(adt)(CO)4(CN)2](2-) [3](2-) (adt(2-) = 1,3-azadithiolate, HN(CH2S(-))2) to give the 2:1 adducts [Fe2(xdt)(CO)4(CNBAr3)2](2-). Attempts to prepare the 1:1 adducts [1(BAr3)](2-) (Ar = Ph, C6F5) were unsuccessful, but related 1:1 adducts were obtained using the bulky borane B(C6F4-o-C6F5)3 (BAr(F)*3). By virtue of the N-protection by the borane, salts of [Fe2(pdt)(CO)4(CNBAr3)2](2-) sustain protonation to give hydrides that are stable (in contrast to [H1](-)). The hydrides [H1(BAr3)2](-) are 2.5-5 pKa units more acidic than the parent [H1](-). The adducts [1(BAr3)2](2-) oxidize quasi-reversibly around -0.3 V versus Fc(0/+) in contrast to ca. -0.8 V observed for the [1](2-/-) couple. A simplified synthesis of [1](2-), [3](2-), and [Fe2(pdt)(CO)5(CN)](-) ([2](-)) was developed, entailing reaction of the diiron hexacarbonyl complexes with KCN in MeCN.
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Affiliation(s)
- Brian C. Manor
- School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801, United States
| | - Mark R. Ringenberg
- School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801, United States
| | - Thomas B. Rauchfuss
- School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801, United States
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Greb L, Daniliuc CG, Bergander K, Paradies J. Toleranz gegenüber funktionellen Gruppen bei frustrierten Lewis-Paaren: Hydrierung von Nitroolefinen und Acrylaten. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201210175] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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Greb L, Daniliuc CG, Bergander K, Paradies J. Functional-Group Tolerance in Frustrated Lewis Pairs: Hydrogenation of Nitroolefins and Acrylates. Angew Chem Int Ed Engl 2013; 52:5876-9. [DOI: 10.1002/anie.201210175] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 02/10/2013] [Indexed: 11/11/2022]
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10
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Discovery of Frustrated Lewis Pairs: Intermolecular FLPs for Activation of Small Molecules. Top Curr Chem (Cham) 2012. [DOI: 10.1007/128_2012_381] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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11
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Ashley AE, Herrington TJ, Wildgoose GG, Zaher H, Thompson AL, Rees NH, Krämer T, O'Hare D. Separating electrophilicity and Lewis acidity: the synthesis, characterization, and electrochemistry of the electron deficient tris(aryl)boranes B(C6F5)(3-n)(C6Cl5)n (n = 1-3). J Am Chem Soc 2011; 133:14727-40. [PMID: 21786772 DOI: 10.1021/ja205037t] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new family of electron-deficient tris(aryl)boranes, B(C(6)F(5))(3-n)(C(6)Cl(5))(n) (n = 1-3), has been synthesized, permitting an investigation into the steric and electronic effects resulting from the gradual replacement of C(6)F(5) with C(6)Cl(5) ligands. B(C(6)F(5))(2)(C(6)Cl(5)) (3) is accessed via C(6)Cl(5)BBr(2), itself prepared from donor-free Zn(C(6)Cl(5))(2) and BBr(3). Reaction of C(6)Cl(5)Li with BCl(3) in a Et(2)O/hexane slurry selectively produced B(C(6)Cl(5))(2)Cl, which undergoes B-Cl exchange with CuC(6)F(5) to afford B(C(6)F(5))(C(6)Cl(5))(2) (5). While 3 forms a complex with H(2)O, which can be rapidly removed under vacuum or in the presence of molecular sieves, B(C(6)Cl(5))(3) (6) is completely stable to refluxing toluene/H(2)O for several days. Compounds 3, 5, and 6 have been structurally characterized using single crystal X-ray diffraction and represent the first structure determinations for compounds featuring B-C(6)Cl(5) bonds; each exhibits a trigonal planar geometry about B, despite having different ligand sets. The spectroscopic characterization using (11)B, (19)F, and (13)C NMR indicates that the boron center becomes more electron-deficient as n increases. Optimized structures of B(C(6)F(5))(3-n)(C(6)Cl(5))(n) (n = 0-3) using density functional theory (B3LYP/TZVP) are all fully consistent with the experimental structural data. Computed (11)B shielding constants also replicate the experimental trend almost quantitatively, and the computed natural charges on the boron center increase in the order n = 0 (0.81) < n = 1 (0.89) < n = 2 (1.02) < n = 3 (1.16), supporting the hypothesis that electrophilicity increases concomitantly with substitution of C(6)F(5) for C(6)Cl(5). The direct solution cyclic voltammetry of B(C(6)F(5))(3) has been obtained for the first time and electrochemical measurements upon the entire series B(C(6)F(5))(3-n)(C(6)Cl(5))(n) (n = 0-3) corroborate the spectroscopic data, revealing C(6)Cl(5) to be a more electron-withdrawing group than C(6)F(5), with a ca. +200 mV shift observed in the reduction potential per C(6)F(5) group replaced. Conversely, use of the Guttmann-Beckett and Childs' methods to determine Lewis acidity on B(C(6)F(5))(3), 3, and 5 showed this property to diminish with increasing C(6)Cl(5) content, which is attributed to the steric effects of the bulky C(6)Cl(5) substituents. This conflict is ascribed to the minimal structural reorganization in the radical anions upon reduction during cyclic voltammetric experiments. Reduction of 6 using Na((s)) in THF results in a vivid blue paramagnetic solution of Na(+) [6](•-); the EPR signal of Na(+)[6](•-) is centered at g = 2.002 with a((11)B) 10G. Measurements of the exponential decay of the EPR signal (298 K) reveal [6](•-) to be considerably more stable than its perfluoro analogue.
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Affiliation(s)
- Andrew E Ashley
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, United Kingdom.
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Mewald M, Fröhlich R, Oestreich M. An Axially Chiral, Electron-Deficient Borane: Synthesis, Coordination Chemistry, Lewis Acidity, and Reactivity. Chemistry 2011; 17:9406-14. [DOI: 10.1002/chem.201100724] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Indexed: 11/09/2022]
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13
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Dureen MA, Brown CC, Stephan DW. Deprotonation and Addition Reactions of Frustrated Lewis Pairs with Alkynes. Organometallics 2010. [DOI: 10.1021/om1009044] [Citation(s) in RCA: 176] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Meghan A. Dureen
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada, M5S 3H6
| | - Christopher C. Brown
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada, M5S 3H6
| | - Douglas W. Stephan
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada, M5S 3H6
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Erős G, Mehdi H, Pápai I, Rokob T, Király P, Tárkányi G, Soós T. Expanding the Scope of Metal-Free Catalytic Hydrogenation through Frustrated Lewis Pair Design. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201001518] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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15
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Erős G, Mehdi H, Pápai I, Rokob T, Király P, Tárkányi G, Soós T. Expanding the Scope of Metal-Free Catalytic Hydrogenation through Frustrated Lewis Pair Design. Angew Chem Int Ed Engl 2010; 49:6559-63. [DOI: 10.1002/anie.201001518] [Citation(s) in RCA: 213] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Štefane B. Selective Addition of Organolithium Reagents to BF2-Chelates of β-Ketoesters. Org Lett 2010; 12:2900-3. [DOI: 10.1021/ol100620j] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Bogdan Štefane
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana, Slovenia
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Neu RC, Ouyang EY, Geier SJ, Zhao X, Ramos A, Stephan DW. Probing substituent effects on the activation of H2 by phosphorus and boron frustrated Lewis pairs. Dalton Trans 2010; 39:4285-94. [DOI: 10.1039/c001133a] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Stephan D, Erker G. Frustrated Lewis Pairs: Metal-free Hydrogen Activation and More. Angew Chem Int Ed Engl 2009; 49:46-76. [DOI: 10.1002/anie.200903708] [Citation(s) in RCA: 1641] [Impact Index Per Article: 109.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Stephan D, Erker G. Frustrierte Lewis-Paare: metallfreie Wasserstoffaktivierung und mehr. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200903708] [Citation(s) in RCA: 640] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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20
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Otten E, Neu RC, Stephan DW. Complexation of Nitrous Oxide by Frustrated Lewis Pairs. J Am Chem Soc 2009; 131:9918-9. [DOI: 10.1021/ja904377v] [Citation(s) in RCA: 251] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Edwin Otten
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada, M5S 3H6
| | - Rebecca C. Neu
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada, M5S 3H6
| | - Douglas W. Stephan
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada, M5S 3H6
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Rokob TA, Hamza A, Pápai I. Rationalizing the Reactivity of Frustrated Lewis Pairs: Thermodynamics of H2 Activation and the Role of Acid−Base Properties. J Am Chem Soc 2009; 131:10701-10. [DOI: 10.1021/ja903878z] [Citation(s) in RCA: 269] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tibor András Rokob
- Chemical Research Center of the Hungarian Academy of Sciences, P.O. Box 17, H-1525 Budapest, Hungary
| | - Andrea Hamza
- Chemical Research Center of the Hungarian Academy of Sciences, P.O. Box 17, H-1525 Budapest, Hungary
| | - Imre Pápai
- Chemical Research Center of the Hungarian Academy of Sciences, P.O. Box 17, H-1525 Budapest, Hungary
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Pouget E, Holgado-Garcia E, Vasilenko IV, Kostjuk SV, Campagne JM, Ganachaud F. Oligomerization of electron-deficient vinyl monomers through an ate-complex mechanism: a new role for b(c(6) f(5) )(3) lewis Acid. Macromol Rapid Commun 2009; 30:1128-32. [PMID: 21706577 DOI: 10.1002/marc.200900173] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 03/23/2009] [Indexed: 11/05/2022]
Abstract
The Lewis acid B(C(6) F(5) )(3) in combination with hydrosilanes exhibits remarkable activity in the oligomerization of sulfone- and phosphonate-based monomers. This process opens new routes to high-tech silicone-based materials, i.e., thermoplastic elastomers and heat-resistant polysiloxanes.
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Affiliation(s)
- Emmanuel Pouget
- Institut Charles Gerhardt - UMR 5253 CNRS/UM2/ENSCM/UM1, Ecole Nationale Supérieure de Chimie de Montpellier, 8 rue de l'Ecole Normale, 34296 Montpellier Cedex 5, France
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Welch GC, Prieto R, Dureen MA, Lough AJ, Labeodan OA, Höltrichter-Rössmann T, Stephan DW. Reactions of phosphines with electron deficient boranes. Dalton Trans 2009:1559-70. [DOI: 10.1039/b814486a] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wang SX, Wang MX, Wang DX, Zhu J. Chiral salen-aluminum complex as a catalyst for enantioselective alpha-addition of isocyanides to aldehydes: asymmetric synthesis of 2-(1-hydroxyalkyl)-5-aminooxazoles. Org Lett 2007; 9:3615-8. [PMID: 17685533 DOI: 10.1021/ol7014658] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the presence of a catalytic amount of (salen)Al(III)Cl complex (4e), reaction between alpha-isocyanoacetamides (1) and aldehydes (2) afforded the corresponding 5-aminooxazoles (3) in good yields and enantioselectivity.
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Affiliation(s)
- Shi-Xin Wang
- National Laboratory for Molecular Sciences, Laboratory of Chemical Biology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China
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Welch GC, Cabrera L, Chase PA, Hollink E, Masuda JD, Wei P, Stephan DW. Tuning Lewis acidity using the reactivity of “frustrated Lewis pairs”: facile formation of phosphine-boranes and cationic phosphonium-boranes. Dalton Trans 2007:3407-14. [PMID: 17664977 DOI: 10.1039/b704417h] [Citation(s) in RCA: 254] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The concept of "frustrated Lewis pairs" involves donor and acceptor sites in which steric congestion precludes Lewis acid-base adduct formation. In the case of sterically demanding phosphines and boranes, this lack of self-quenching prompts nucleophilic attack at a carbon para to B followed by fluoride transfer affording zwitterionic phosphonium borates [R(3)P(C(6)F(4))BF(C(6)F(5))(2)] and [R(2)PH(C(6)F(4))BF(C(6)F(5))(2)]. These can be easily transformed into the cationic phosphonium-boranes [R(3)P(C(6)F(4))B(C(6)F(5))(2)](+) and [R(2)PH(C(6)F(4))B(C(6)F(5))(2)](+) or into the neutral phosphino-boranes R(2)P(C(6)F(4))B(C(6)F(5))(2). This new reactivity provides a modular route to a family of boranes in which the steric features about the Lewis acidic center remains constant and yet the variation in substitution provides a facile avenue for the tuning of the Lewis acidity. Employing the Gutmann-Beckett and Childs methods for determining Lewis acid strength, it is demonstrated that the cationic boranes are much more Lewis acidic than B(C(6)F(5))(3), while the acidity of the phosphine-boranes is diminished.
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Affiliation(s)
- Gregory C Welch
- Department of Chemistry & Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B3P4
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Chase PA, Romero PE, Piers WE, Parvez M, Patrick BO. Fluorinated 9-borafluorenes vs. conventional perfluoroaryl boranes Comparative Lewis acidity. CAN J CHEM 2005. [DOI: 10.1139/v05-240] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Perfluorinated 9-phenyl-9-borafluorene, 1, is an antiaromatic analog of the well-known tris(pentafluorophenyl)borane. Spectroscopic, structural, and electrochemical studies have been performed on 1 and its Lewis base adducts with MeCN, THF, and PMe3 with a view to assessing its comparative Lewis acid strength relative to B(C6F5)3. For the sterically undemanding Lewis base MeCN, 1 and B(C6F5)3 have comparable LA strengths, while for more sterically prominent THF, 1 is clearly the stronger Lewis acid (LA) based on competition experiments. We conclude that steric factors, rather than antiaromaticity, are the most important determinants in the LA strength differences between 1 and B(C6F5)3.Key words: boranes, Lewis acids, fluorinated compounds, heterocycles.
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Yoshioka S, Oshita M, Tobisu M, Chatani N. GaCl3-Catalyzed Insertion of Isocyanides into a C−O Bond in Cyclic Ketals and Acetals. Org Lett 2005; 7:3697-9. [PMID: 16092853 DOI: 10.1021/ol0513138] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction of cyclic ketals or acetals with 2,6-dibromophenylisocyanide in the presence of a catalytic amount of GaCl(3) results in the insertion of isocyanide into the carbon-oxygen bond of cyclic ketals and acetals. [reaction: see text]
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Affiliation(s)
- Sachiko Yoshioka
- Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
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Britovsek GJP, Ugolotti J, White AJP. From B(C6F5)3 to B(OC6F5)3: Synthesis of (C6F5)2BOC6F5 and C6F5B(OC6F5)2 and Their Relative Lewis Acidity. Organometallics 2005. [DOI: 10.1021/om049091p] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
| | - Juri Ugolotti
- Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AY, U.K
| | - Andrew J. P. White
- Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AY, U.K
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Erker G. Tris(pentafluorophenyl)borane: a special boron Lewis acid for special reactions. Dalton Trans 2005:1883-90. [PMID: 15909033 DOI: 10.1039/b503688g] [Citation(s) in RCA: 304] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tris(pentafluorophenyl)borane is best known for its role as an excellent activator component in homogeneous Ziegler-Natta chemistry. However, the special properties of B(C6F5)3 have made this strong boron Lewis acid an increasingly used catalyst or stoichiometric reagent in organic and organometallic chemistry. This includes catalytic hydrometallation reactions, alkylations and catalyzed aldol-type reactions. B(C6F5)3 catalyzes tautomerizations and can sometimes stabilize less favoured tautomeric forms by adduct formation. It induces some rather unusual reactions of early metal acetylide complexes and can help in stabilizing uncommon coordination geometries of carbon. The growing number of such examples indicates an increasing application potential of the useful Lewis acid B(C6F5)3 aside from its established role in olefin polymerization catalysis.
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Affiliation(s)
- Gerhard Erker
- Organisch-Chemisches Institut der Universität Münster, Corrensstrasse 40, 48149 Münster, Germany.
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Oshita M, Yamashita K, Tobisu M, Chatani N. Catalytic [4+1] Cycloaddition of α,β-Unsaturated Carbonyl Compounds with Isocyanides. J Am Chem Soc 2004; 127:761-6. [PMID: 15643902 DOI: 10.1021/ja0450206] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The GaCl(3)-catalyzed [4+1] cycloaddition reactions of alpha,beta-unsaturated ketones with isocyanides leading to lactone derivatives are described. While some other Lewis acids also show catalytic activity, GaCl(3) was the most efficient catalyst. The reaction is significantly affected by the structure of both the isocyanides and the alpha,beta-unsaturated ketones. Aromatic isocyanides, especially sterically demanding ones and those bearing an electron-withdrawing group, can be used, but aliphatic isocyanides cannot. The bulkiness of substituents at the beta-position of acyclic alpha,beta-unsaturated ketones is an important factor for the reaction to proceed efficiently. Generally, the more the bulky substituent, the higher is the yield. The reaction of alpha,beta-unsaturated ketones bearing geminal substituents at the beta-position gave the corresponding products in high yields. In monosubstituted derivatives, the yields are relatively low. However, substrates having a bulky substituent, such as a tert-Bu group, at the beta-position give high yields. Bulkiness is also required in cyclic alpha,beta-unsaturated ketones, but the effect is small. In alkyl vinyl ketones, the reactivity decreased with the steric bulk of the alkyl group. In aryl vinyl ketones, the presence of an electron-donating group on the aromatic ring decreases the reactivity. The success of the catalysis can be attributed to the low affinity of GaCl(3) toward heteroatoms, compared with usual Lewis acids.
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Affiliation(s)
- Masayuki Oshita
- Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
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Qin Y, Cheng G, Achara O, Parab K, Jäkle F. A New Route to Organoboron Polymers via Highly Selective Polymer Modification Reactions. Macromolecules 2004. [DOI: 10.1021/ma035880r] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yang Qin
- Department of Chemistry, Rutgers UniversityNewark, 73 Warren Street, Newark, New Jersey 07102
| | - Guanglou Cheng
- Department of Chemistry, Rutgers UniversityNewark, 73 Warren Street, Newark, New Jersey 07102
| | - Obianuju Achara
- Department of Chemistry, Rutgers UniversityNewark, 73 Warren Street, Newark, New Jersey 07102
| | - Kshitij Parab
- Department of Chemistry, Rutgers UniversityNewark, 73 Warren Street, Newark, New Jersey 07102
| | - Frieder Jäkle
- Department of Chemistry, Rutgers UniversityNewark, 73 Warren Street, Newark, New Jersey 07102
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