1
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Hédouin M, Barthelemy AL, Vanthuyne N, Besrour H, Maddaluno J, Magnier E, Oulyadi H. NMR and DFT Studies with a Doubly Labelled 15 N/ 6 Li S-Trifluoromethyl Sulfoximine Reveal Why a Directed ortho-Lithiation Requires an Excess of n-BuLi. Angew Chem Int Ed Engl 2023; 62:e202214106. [PMID: 36377763 PMCID: PMC10108270 DOI: 10.1002/anie.202214106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Indexed: 11/16/2022]
Abstract
This work shows why it is imperious to use an excess of butyllithium for a directed ortho-lithiation of a trifluoromethyl sulfoximine. The analysis of mixtures of n-BuLi and sulfoximine 1 in THF-d8 using {1 H, 6 Li, 13 C, 15 N, 19 F} NMR experiments at low temperatures reveal that a first deprotonation occurs that leads to dimeric and tetrameric N-lithiated sulfoximine (93 : 7). Using an excess n-BuLi (5 equivalents), the second deprotonation on the ortho-position of the aromatic occurs. Six species were observed and characterized on the way. It includes three aggregates involving a sulfoximine: i) a [dilithiated sulfoximine/(n-BuLi)] dimer solvated by four molecules of THF (Agg2, 39 %); ii) a [dilithiated sulfoximine/(n-BuLi)3 ] tetramer solvated by six molecules of THF (Agg3, 39 %); iii) a [dilithiated sulfoximine/(n-BuOLi)3 ] tetramer solvated by four molecules of THF (Agg1, 22 %). A DFT study afforded optimized solvated structures for all these aggregates, fully consistent with the NMR data.
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Affiliation(s)
- Matthieu Hédouin
- Laboratoire COBRA (UMR 6014 & FR 3038), Normandie Université, UNIROUEN, INSA Rouen, CNRS Rue Tesniere, 76821, Mont Saint Aignan, France
| | - Anne-Laure Barthelemy
- Institut Lavoisier de Versailles (UMR 8180), Université Paris-Saclay, UVSQ, CNRS, 45 avenue des Etats-Unis, 78035, Versailles, France
| | - Nicolas Vanthuyne
- iSm2, UMR 7313, Aix Marseille Univ, CNRS, Centrale Marseille, AMUtech, 13288, Marseille, France
| | - Hend Besrour
- Laboratoire COBRA (UMR 6014 & FR 3038), Normandie Université, UNIROUEN, INSA Rouen, CNRS Rue Tesniere, 76821, Mont Saint Aignan, France
| | - Jacques Maddaluno
- Laboratoire COBRA (UMR 6014 & FR 3038), Normandie Université, UNIROUEN, INSA Rouen, CNRS Rue Tesniere, 76821, Mont Saint Aignan, France
| | - Emmanuel Magnier
- Institut Lavoisier de Versailles (UMR 8180), Université Paris-Saclay, UVSQ, CNRS, 45 avenue des Etats-Unis, 78035, Versailles, France
| | - Hassan Oulyadi
- Laboratoire COBRA (UMR 6014 & FR 3038), Normandie Université, UNIROUEN, INSA Rouen, CNRS Rue Tesniere, 76821, Mont Saint Aignan, France
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2
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Zhang GP, Huang S, Jiang YJ, Liu XY, Ding CH, Wei Y, Hou XL. Pd-catalyzed enantioselective cyclopropanation of nitriles with mono substituted allyl carbonates enabled by the bulky N-heterocyclic carbene ligand. Chem Commun (Camb) 2019; 55:6449-6452. [DOI: 10.1039/c9cc01960j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Enantioselective cyclopropanation of nitriles with allyl reagents was realized using Pd/NHC as a catalyst and the reasons for the cyclopropanation were investigated.
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Affiliation(s)
- Gao-Peng Zhang
- State Key Laboratory of Organometallic Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences (SIOC)
- China
| | - Shuai Huang
- State Key Laboratory of Organometallic Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences (SIOC)
- China
| | - Yang-Jie Jiang
- State Key Laboratory of Organometallic Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences (SIOC)
- China
| | - Xiu-Yan Liu
- State Key Laboratory of Organometallic Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences (SIOC)
- China
| | - Chang-Hua Ding
- State Key Laboratory of Organometallic Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences (SIOC)
- China
| | - Yin Wei
- State Key Laboratory of Organometallic Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences (SIOC)
- China
| | - Xue-Long Hou
- State Key Laboratory of Organometallic Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences (SIOC)
- China
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3
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Pitta BR, Steward OW, Fleming FF. Electrophile-Dependent Alkylations of Lithiated 4-Alkoxyalk-4-enenitriles. J Org Chem 2018; 83:2753-2762. [PMID: 29432696 DOI: 10.1021/acs.joc.7b03205] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alkylations of acyclic, lithiated 4-alkoxyalk-4-enenitriles are highly diastereoselective with an unusual electrophile-dependent preference. Alkyl halides, sulfur, chlorine, and acyl cyanide electrophiles intercept a series of lithiated 4-alkoxyalk-4-enenitriles to install contiguous tertiary-quaternary stereocenters with high diastereoselectivity, whereas acylations with ester and carbonate electrophiles are modestly selective. The diastereoselectivity is consistent with electrophilic attack on the most accessible face of the lithated nitrile for most electrophiles except ester and carbonate electrophiles, which likely precoordinate the lithiated nitrile before acylation. Intercepting the lithiated 4-alkoxyalk-4-enenitriles with a range of electrophiles provide insight into the criteria for otherwise challenging diastereoselective alkylations and acylations of acyclic nitriles.
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Affiliation(s)
| | - Omar W Steward
- Department of Chemistry and Biochemistry, Duquesne University , Pittsburgh, Pennsylvania 15282, United States
| | - Fraser F Fleming
- Department of Chemistry, Drexel University , Philadelphia, Pennsylvania 19104, United States
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Yang X, Fleming FF. C- and N-Metalated Nitriles: The Relationship between Structure and Selectivity. Acc Chem Res 2017; 50:2556-2568. [PMID: 28930437 DOI: 10.1021/acs.accounts.7b00329] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Metalated nitriles are exceptional nucleophiles capable of forging highly hindered stereocenters in cases where enolates are unreactive. The excellent nucleophilicity emanates from the powerful inductive stabilization of adjacent negative charge by the nitrile, which has a miniscule steric demand. Inductive stabilization is the key to understanding the reactivity of metalated nitriles because this permits a continuum of structures that range from N-metalated ketenimines to nitrile anions. Solution and solid-state analyses reveal two different metal coordination sites, the formally anionic carbon and the nitrile nitrogen, with the site of metalation depending intimately on the solvent, counterion, temperature, and ligands. The most commonly encountered structures, C- and N-metalated nitriles, have either sp3 or sp2 hybridization at the nucleophilic carbon, which essentially translates into two distinct organometallic species with similar but nonidentical stereoselectivity, regioselectivity, and reactivity preferences. The hybridization differences are particularly important in SNi displacements of cyclic nitriles because the orbital orientations create very precise trajectories that control the cyclization selectivity. Harnessing the orbital differences between C- and N-metalated nitriles allows selective cyclization to afford nitrile-containing cis- or trans-hydrindanes, decalins, or bicyclo[5.4.0]undecanes. Similar orbital constraints favor preferential SNi displacements with allylic electrophiles on sp3 centers over sp2 centers. The strategy permits stereoselective displacements on secondary centers to set contiguous tertiary and quaternary stereocenters or even contiguous vicinal quaternary centers. Stereoselective alkylations of acyclic nitriles are inherently more challenging because of the difficulty in creating steric differentiation in a dynamic system with rotatable bonds. However, judicious substituent placement of vicinal dimethyl groups and a trisubstituted alkene sufficiently constrains C- and N-metalated nitriles to install quaternary stereocenters with excellent 1,2-induction. The structural differences between C- and N-metalated nitriles permit a rare series of chemoselective alkylations with bifunctional electrophiles. C-Magnesiated nitriles preferentially react with carbonyl electrophiles, whereas N-lithiated nitriles favor SN2 displacement of alkyl halides. The chemoselective alkylations potentially provide a strategy for late-stage alkylations of polyfunctional electrophiles en route to bioactive targets. In this Account, the bonding of metalated nitriles is summarized as a prelude to the different strategies for selectively preparing C- and N-metalated nitriles. With this background, the Account then transitions to applications in which C- or N-metalated nitriles allow complementary diastereoselectivity in alkylations and arylations, and regioselective alkylations and arylations, with acyclic and cyclic nitriles. In the latter sections, a series of regiodivergent cyclizations are described that provide access to cis- and trans-hydrindanes and decalins, structural motifs embedded within a plethora of natural products. The last section describes chemoselective alkylations and acylations of C- and N-metalated nitriles that offer the tantalizing possibility of selectively manipulating functional groups in bioactive medicinal leads without recourse to protecting groups. Collectively, the unusual reactivity profiles of C- and N-metalated nitriles provide new strategies for rapidly and selectively accessing valuable synthetic precursors.
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Affiliation(s)
- Xun Yang
- Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Fraser F. Fleming
- Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, United States
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Jiao Z, Chee KW, Zhou J“S. Palladium-Catalyzed Asymmetric α-Arylation of Alkylnitriles. J Am Chem Soc 2016; 138:16240-16243. [DOI: 10.1021/jacs.6b11610] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Zhiwei Jiao
- Division of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Kwok Wei Chee
- Division of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Jianrong “Steve” Zhou
- Division of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
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6
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Večeřa M, Varga V, Císařová I, Pinkas J, Kucharczyk P, Sedlařík V, Lamač M. Group 4 Metal Complexes of Chelating Cyclopentadienyl-ketimide Ligands. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Miloš Večeřa
- J.
Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, v.v.i., Dolejškova 2155/3, 18223 Prague 8, Czech Republic
- Department
of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 12840 Prague 2, Czech Republic
| | - Vojtech Varga
- J.
Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, v.v.i., Dolejškova 2155/3, 18223 Prague 8, Czech Republic
| | - Ivana Císařová
- Department
of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 12840 Prague 2, Czech Republic
| | - Jiří Pinkas
- J.
Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, v.v.i., Dolejškova 2155/3, 18223 Prague 8, Czech Republic
| | - Pavel Kucharczyk
- Centre
of Polymer Systems, University Institute, Tomáš Bat’a University in Zlín, tř. T. Bati 5678, 76001 Zlín, Czech Republic
| | - Vladimír Sedlařík
- Centre
of Polymer Systems, University Institute, Tomáš Bat’a University in Zlín, tř. T. Bati 5678, 76001 Zlín, Czech Republic
| | - Martin Lamač
- J.
Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, v.v.i., Dolejškova 2155/3, 18223 Prague 8, Czech Republic
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7
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Qin W, Long S, Bongini A, Panunzio M. α-Alkyl-α-aryl (Trimethyltin) Nitriles: Versatile Nucleophilic Intermediates in Aldol-Like Reactions. European J Org Chem 2015. [DOI: 10.1002/ejoc.201500299] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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8
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Nath D, Skilbeck MC, Coldham I, Fleming FF. Arylthio-Metal Exchange of α-Arylthioalkanenitriles. Org Lett 2013; 16:62-5. [PMID: 24328754 DOI: 10.1021/ol403020s] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Dinesh Nath
- Department of Chemistry & Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530, United States
| | | | - Iain Coldham
- Department
of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Fraser F. Fleming
- Department of Chemistry & Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530, United States
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9
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Harrison-Marchand A, Mongin F. Mixed AggregAte (MAA): A Single Concept for All Dipolar Organometallic Aggregates. 1. Structural Data. Chem Rev 2013; 113:7470-562. [DOI: 10.1021/cr300295w] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anne Harrison-Marchand
- Laboratoire COBRA de l′Université de Rouen, INSA de Rouen, CNRS, UMR 6014 & FR 3038, IRCOF, Rue Tesnière, 76821 Mont St Aignan Cédex, France
| | - Florence Mongin
- Équipe Chimie et Photonique Moléculaires, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Bâtiment 10A, case 1003, Avenue du Général Leclerc, 35042 Rennes Cédex, France
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10
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Reich HJ. Role of Organolithium Aggregates and Mixed Aggregates in Organolithium Mechanisms. Chem Rev 2013; 113:7130-78. [DOI: 10.1021/cr400187u] [Citation(s) in RCA: 248] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Hans J. Reich
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
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11
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Chirality transfer in Brook rearrangement-mediated SE2′ solvolytic protonation and its use in estimation of the propensity for racemization of the α-lithiocarbanions of the substituents. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.05.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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12
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Purzycki M, Liu W, Hilmersson G, Fleming FF. Metalated nitriles: N- and C-coordination preferences of Li, Mg, and Cu cations. Chem Commun (Camb) 2013; 49:4700-2. [DOI: 10.1039/c3cc41703d] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Nath D, Fleming FF. Sulfinylnitriles: Sulfinyl-Metal Exchange-Alkylation Strategies. Chemistry 2012; 19:2023-9. [DOI: 10.1002/chem.201203174] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Indexed: 11/09/2022]
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14
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15
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Kagan G, Li W, Hopson R, Williard PG. 6Li diffusion-ordered NMR spectroscopy (DOSY) and applications to organometallic complexes. Org Lett 2010; 12:520-3. [PMID: 20041695 DOI: 10.1021/ol902713h] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The development of (6)Li diffusion-ordered NMR spectroscopy (DOSY) is reported. This technique is applied to (6)Li organometallic complexes. (6)Li DOSY provides a facile means of identification of peaks in the (6)Li spectrum, as well as evidence of mixed aggregates based on relative diffusion coefficients. (6)Li data is correlated to (1)H diffusion experiments through (6)Li{(1)H} HOESY and/or (1)H{(6)Li} HMBC experiments to obtain formula weight information of Li aggregates.
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Affiliation(s)
- Gerald Kagan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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16
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Fleming FF, Gudipati S. Cyclic Metalated Nitriles: Stereoselective Cyclizations to cis- and trans-Hydrindanes, Decalins, and Bicyclo[4.3.0]undecanes. European J Org Chem 2008; 2008:10.1002/ejoc.200800715. [PMID: 24260015 PMCID: PMC3831376 DOI: 10.1002/ejoc.200800715] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Indexed: 11/07/2022]
Abstract
Metalated nitriles are nucleophilic chameleons whose precise identity is determined by the nature of the metal, the solvent, the temperature, and the structure of the nitrile. The review surveys the different structural types and their cyclization trajectories to show how to selectively tune the metalated nitrile geometry for stereoselective cyclizations to a variety of cis or trans hydrindanes, decalins, and bicyclo[4.3.0]undecanes.
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Affiliation(s)
- Fraser F. Fleming
- Department of Chemistry and Biochemistry, Mellon Hall, Duquesne University, Pittsburgh PA 15282-1530, USA
| | - Subramanyham Gudipati
- Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, N.J. 07033-0530, USA Fax: +1-908-740-7441
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17
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Li D, Sun C, Williard PG. Characterization of a Chiral Enolate Aggregate and Observation of 6Li−1H Scalar Coupling. J Am Chem Soc 2008; 130:11726-36. [DOI: 10.1021/ja802114j] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Deyu Li
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
| | - Chengzao Sun
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
| | - Paul G. Williard
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
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18
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Fleming FF, Wei Y, Liu W, Zhang Z. Metalated Nitriles: Stereodivergent Cation-Controlled Cyclizations1. Tetrahedron 2008; 64:7477-7488. [PMID: 19657380 PMCID: PMC2597827 DOI: 10.1016/j.tet.2008.05.110] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Stereodivergent cyclizations of gamma-hydroxy cyclohexanecarbonitriles are controlled simply through judicious choice of cation in the alkylmetal base. Deprotonating a series of cyclic gamma-hydroxy nitriles with i-PrMgBr generates C-magnesiated nitriles that cyclize under stereoelectronic control to cis-fused hydrindanes, decalins, and bicyclo [5.4.0] undecanes. An analogous deprotonation with BuLi triggers cyclization to trans-fused hydrindanes, decalins, and bicyclo [5.4.0] undecanes consistent with a sterically controlled electrophilic attack on an equatorial nitrile anion. Using cations to control the geometry of metalated nitriles provides a versatile, stereodivergent cyclization to cis- and trans-hydrindanes, decalins, and [5. 4. 0] undecanes, and reveals the key geometric requirements for intramolecular S(N)2 and S(N)2' displacements.
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Affiliation(s)
- Fraser F. Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530,
| | - Yunjing Wei
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530,
| | - Wang Liu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530,
| | - Zhiyu Zhang
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530,
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Fleming FF, Liu W, Ghosh S, Steward OW. Metalated Nitriles: Internal 1,2-Asymmetric Induction. J Org Chem 2008; 73:2803-10. [DOI: 10.1021/jo702681e] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Fraser F. Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530
| | - Wang Liu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530
| | - Somraj Ghosh
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530
| | - Omar W. Steward
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530
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Abstract
Judicious choice of cation allows the selective cyclization of substituted gamma-hydroxynitriles to trans- or cis-decalins and trans- or cis-bicyclo[5.4.0]undecanes. The stereoselectivities are consistent with deprotonations generating two distinctly different metalated nitriles: an internally coordinated nitrile anion with BuLi, and a C-magnesiated nitrile with i-PrMgCl. Employing cations to control the geometry of metalated nitriles permits stereodivergent cyclizations with complete control over the stereochemistry of the quaternary, nitrile-bearing carbon.
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Affiliation(s)
- Fraser F Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282-1530, USA.
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21
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Braun L, Kehr G, Blömker T, Fröhlich R, Erker G. Preferred Phosphorus Ylide Formation Upon Alkylation of Lithiobis(diphenylphosphanyl)acetonitrile. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200700082] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Leonie Braun
- Universität Münster, Organisch‐Chemisches Institut, Corrensstrasse 40, 48149 Münster, Germany, Fax: +49‐251‐83‐36503
| | - Gerald Kehr
- Universität Münster, Organisch‐Chemisches Institut, Corrensstrasse 40, 48149 Münster, Germany, Fax: +49‐251‐83‐36503
| | - Tobias Blömker
- Universität Münster, Organisch‐Chemisches Institut, Corrensstrasse 40, 48149 Münster, Germany, Fax: +49‐251‐83‐36503
| | - Roland Fröhlich
- Universität Münster, Organisch‐Chemisches Institut, Corrensstrasse 40, 48149 Münster, Germany, Fax: +49‐251‐83‐36503
| | - Gerhard Erker
- Universität Münster, Organisch‐Chemisches Institut, Corrensstrasse 40, 48149 Münster, Germany, Fax: +49‐251‐83‐36503
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Fleming FF, Vu VA, Shook BC, Rahman M, Steward OW. Metalated Nitriles: Chelation-Controlled Cyclizations to cis and trans Hydrindanes and Decalins. J Org Chem 2007; 72:1431-6. [PMID: 17249734 DOI: 10.1021/jo062270r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chelation provides a powerful means of stereocontrol in alkylations of metalated nitriles. Doubly deprotonating a series of cyclic beta-hydroxynitriles triggers cyclizations that implicate metalated nitrile intermediates having configurations imposed by chelation with an adjacent, chiral lithium alkoxide. Identifying chelation as a general stereocontrol element explains several previously anomalous alkylations of metalated nitriles and provides a potential solution to the long-standing difficulty of synthesizing trans-hydrindanes. Employing chelation to control the metalated nitrile geometry permits selective cyclizations to cis and trans hydrindanes and decalins and provides key insight into the geometrical requirements of these demanding cyclizations.
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Affiliation(s)
- Fraser F Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282-1530, USA.
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Braun L, Liptau P, Kehr G, Ugolotti J, Fröhlich R, Erker G. Bis(diphenylphosphino)acetonitrile: Synthesis, ligand properties and application in catalytic carbon–carbon coupling. Dalton Trans 2007:1409-15. [PMID: 17387401 DOI: 10.1039/b616847g] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Treatment of acetonitrile (1 equiv.) with n-butyllithium (0.95 equiv.) followed by chlorodiphenylphosphine (0.95 equiv.) under optimised reaction conditions gave a ca. 60% yield of bis(diphenylphosphino)acetonitrile (dppmCN, 1). The bidentate ligand was employed in the synthesis of the four-membered chelate metal complexes (dppmCN)MCl(2) [M = Pd (6a), Pt (6b)] and (dppmCN)RuCp*(Cl) (7). A very active catalyst for bromobenzene/phenylboronic acid Suzuki-Miyaura coupling was in situ generated by treatment of Pd(OAc)(2) with bis(diphenylphosphino)acetonitrile [TOF (1 h) >600000].
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Affiliation(s)
- Leonie Braun
- Organisch-Chemisches Institut der Universität Münster, Corrensstrasse 40, 48149, Münster, Germany
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Fleming FF, Zhang Z, Wei G, Steward OW. C-metalated nitriles: electrophile-dependent alkylations and acylations. J Org Chem 2006; 71:1430-5. [PMID: 16468790 PMCID: PMC1896272 DOI: 10.1021/jo052102j] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sequential carbonyl addition-conjugate addition of Grignard reagents to 3-oxocyclohex-1-ene-1-carbonitrile generates C-magnesiated nitriles whose alkylation stereoselectivities intimately depend on the nature of the electrophile. The alkylation of these C-magnesiated nitriles with alkyl halides, sulfonates, and unstrained ketones occurs with the retention of the C-Mg configuration, whereas aldehyde and acyl cyanide acylations proceed with inversion of the stereochemistry. Mechanistic probes indicate that the stereoselectivity is controlled by stereoelectronic effects for most electrophiles, except allylic, benzylic, and cyclopropyl halides where single-electron-transfer processes intervene. Screening numerous alkylations of C-magnesiated nitriles with a diverse range of electrophiles reveals the reaction scope and delineates the fundamental stereoelectronic effects responsible for the highly unusual electrophile-dependent alkylations.
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Affiliation(s)
- Fraser F Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530, USA.
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MacDougall DJ, Kennedy AR, Noll BC, Henderson KW. Synthesis of mono- and geminal dimetalated carbanions of bis(phenylsulfonyl)methane using alkali metal bases and structural comparisons with lithiated bis(phenylsulfonyl)imides. Dalton Trans 2005:2084-91. [PMID: 15957047 DOI: 10.1039/b504730g] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The alpha,alpha'-stabilized carbanion complexes [(PhSO2)2CHLi.THF]1, [(PhSO2)2CHNa.THF]2 and [(PhSO2)2CHK]3 were prepared by the direct deprotonation of bis(phenylsulfonyl)methane I in THF with one molar equivalent of MeLi, BuNa and BnK respectively. The geminal dianionic complexes [(PhSO2)2CLi2.THF]4, [(PhSO2)2CNa2.0.55THF]5 and [(PhSO2)2CK2]6 were similarly prepared by the reaction of I with two molar equivalents of MeLi, BuNa and BnK respectively in THF. NMR and MS solution studies of 1-3 are consistent with the formation of charge-separated species in DMSO media. Solutions studies of 4-6, in conjunction with trapping experiments, indicate that the dianions deprotonate DMSO and regenerate the monoanions 1-3. Crystallographic analysis of 1 revealed a 1D chain polymer in which the metal centers are chelated by the bis(sulfonyl) ligands and connect to neighboring units through Li-O(S) interactions. An unexpected feature of 1 is that the polymeric chains are homochiral, since the chelating ligands of the backbone adopt the same relative configuration. Also, the phenyl substituents of each chelate in 1 are oriented in a cisoid manner. The sodium derivative 2 adopts a related solid-state structure, where enantiomeric pairs of chains combine to give a 1D ribbon motif. The lithium bis(phenylsulfonyl)imides [(PhSO2)2NLi.THF]9 and [(PhSO2)2NLi.Pyr2]10 were also prepared and structurally characterized. In the solid state 9 has a similar connectivity to that found for 1 but with heterochiral chains. In comparison, the more highly solvated complex 10 forms a 1D polymeric arrangement without chelation of the ligands and with the phenyl substituents oriented in a transoid fashion.
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Affiliation(s)
- Dugald J MacDougall
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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26
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Fleming FF, Gudipati S, Zhang Z, Liu W, Steward OW. Cyclic Nitriles: Diastereoselective Alkylations. J Org Chem 2005; 70:3845-9. [PMID: 15876069 DOI: 10.1021/jo0501184] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text] Diastereoselective alkylations of metalated conformationally locked 4-tert-butylcyclohexanecarbonitrile are highly diastereoselective with magnesium and copper counterions but only modestly diastereoselective with lithium as the counterion. Selective generation of diverse metalated nitriles is readily achieved through bromine-magnesium, -copper, and -lithium exchange reactions of the corresponding bromonitrile or, for lithium, by deprotonating the parent nitrile with lithium diethylamide. Collectively, high alkylation stereoselectivities correlate with the retentive alkylations of C-metalated nitriles, whereas N-lithiated nitriles alkylate with modest selectivity, reflecting minimal steric differences in the corresponding axial and equatorial electrophile trajectories.
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Affiliation(s)
- Fraser F Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530, USA.
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27
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Abstract
[reaction: see text] There have been a number of reports of the kinetic conjugate (1,4) addition of metalated arylacetonitriles to enones. Several proposals have been made to explain this behavior based on nucleophile structure or aggregation state or on the HSAB properties of the reactants. A reexamination of these studies showed that in each case the 1,4 adducts resulted from equilibration of the kinetically formed 1,2 adducts to the more stable 1,4 adducts. Thus, no conclusions about the origins of 1,4 selectivity can be drawn from these experiments. The 1,2 addition, retro-1,2 addition, 1,4 addition, and retro-1,4 addition of lithiophenylacetonitrile to benzylideneacetone were examined, and a free energy level diagram was constructed for the reaction.
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Affiliation(s)
- Hans J Reich
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
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Cainelli G, Galletti P, Giacomini D, Gualandi A, Quintavalla A. Solvation-dependent diastereofacial selectivity: addition of lithioacetonitrile to 2-phenyl propanal. Tetrahedron 2005. [DOI: 10.1016/j.tet.2004.10.062] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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30
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Sott R, Granander J, Hilmersson G. Mixed Complexes Formed by Lithioacetonitrile and Chiral Lithium Amides: Observation of 6Li,15N and 6Li,13C Couplings Due to Both C−Li and N−Li Contacts. J Am Chem Soc 2004; 126:6798-805. [PMID: 15161308 DOI: 10.1021/ja0388461] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
NMR spectroscopic studies have been performed on the mixed complexes formed by the lithium salt of acetonitrile (LiCH(2)CN) and the chiral lithium amides Li-(S)-N-(2-methoxybenzyl)-1-amino-1-phenyl-2-ethoxyethane (Li-1) and Li-(S)-N-isopropyl-2-amino-1-phenyl-3-methoxypropane (Li-2) in diethyl ether and tetrahydrofuran solvent. In diethyl ether Li-1 and LiCH(2)CN form a mixed dimeric (1:1) complex, while Li-2 and LiCH(2)CN form a mixed trimeric (2:1) complex. The dimer undergoes fast exchange between ketenimine and bridged structures. Both (1)J((15)N,(6)Li) and (1)J((13)C,(6)Li) couplings were observed for the respectively isotopically labeled compounds. In the trimeric complex the CH(2)CN anion also undergoes fast degenerate exchange between ketenimine and bridged structures, and the complex appears C(2)-symmetric on the NMR spectroscopy time scale. Both the dimer and trimer complexes have the bridged acetonitrile anion in common, as indicated by the highly shielded alpha-carbon (13)C NMR shifts (delta -6.1 and -7.4, respectively). In tetrahydrofuran only N-metalated mixed LiCH(2)CN dimers were observed for both Li-1 and Li-2 with the less shielded (13)C NMR shifts of delta -2.5 and -2.2 for the alpha-carbon of LiCH(2)CN of the complexes.
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Affiliation(s)
- Richard Sott
- Organic Chemistry, Department of Chemistry, Göteborg University, S-412 96 Göteborg, Sweden
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31
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Corset J, Castellà-Ventura M, Froment F, Strzalko T, Wartski L. Study of the lithiated phenylacetonitrile monoanions and dianions formed according to the lithiated base used (LHMDS, LDA, or n-BuLi). 1. Evidence of heterodimer ("Quadac") or dianion formation by vibrational spectroscopy. J Org Chem 2003; 68:3902-11. [PMID: 12737570 DOI: 10.1021/jo020492t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is evidenced through vibrational spectroscopy that a heterodimer or "Quadac" is formed when an excess of base (LHMDS, LDA, or n-BuLi) is added to PhCH(2)CN in THF, THF-hexane, or THF-toluene solution. The amount of heterodimer increases with the pK(H)(a) of the lithiated base. A dianionic species may be formed through decomposition of this heterodimer if the pK(H)(a) of the base is sufficiently high, as in the case of n-BuLi. With LDA, only a very small amount of dianion is observed, and with LHMDS, no dianion is detected. The predominant dianionic species observed are the linear and bridged separated ion pairs of the dilithiated dianion. The presence of the amine in the medium is of paramount importance. The PhCHCNLi monomer-dimer equilibrium is entropy driven toward the dimer solvated by the amine.
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Affiliation(s)
- Jacques Corset
- LADIR - CNRS (UMR 7075), 2 Rue Henri Dunant, BP 28, 94320 Thiais, France
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Carlier PR. Configurational stability of chiral lithiated cyclopropylnitriles: a density functional study. Chirality 2003; 15:340-7. [PMID: 12666242 DOI: 10.1002/chir.10222] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Chiral, configurationally stable lithiated nitriles would be valuable intermediates for asymmetric carbon-carbon bond-forming reactions. To gain insight into the design of such species, Walborsky's attempted enantioselective deprotonation/trapping reactions of a chiral cyclopropylnitrile were studied computationally up to the MP2(fc)/6-31+G* and B3LYP/6-31+G* levels. Investigation of cyclopropylnitrile/LiNH(2) deprotonation transition structures demonstrated a significant (20-23 kcal/mol) kinetic preference for N-lithiation, and a facile (4-6 kcal/mol barrier) "conducted tour" racemization pathway for the N-lithiated nitrile product. Addition of a model directing group (formyl) to the beta-carbon of the cyclopropyl ring is predicted to significantly favor C-lithiation over N-lithiation, both kinetically and thermodynamically. Thus, chiral beta-Lewis base substituted cyclopropylnitriles may serve as precursors to chiral, configurationally stable organolithium reagents.
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Affiliation(s)
- Paul R Carlier
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA.
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Corset J, Castellà-Ventura M, Froment F, Strzalko T, Wartski L. Structural and vibrational characterization of the mono and dilithiated species derived from phenylacetonitrile in THF by infrared and Raman spectroscopy and density functional theory calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2002; 58:1971-1986. [PMID: 12164496 DOI: 10.1016/s1386-1425(01)00648-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The structures and spectra of mono and dianionic species derived from PhCH2CN under the action of an organic base LHMDS or n-BuLi in THF solution have been investigated by vibrational spectroscopy and DFT calculations. The assignments previously proposed for the monoanion, the bridged, linear and dimeric monoanionic ion pairs compare well with the calculated ones. The addition of HMPA to a THF solution of PhCHCNLi leads to the formation of an HMPA solvated linear ion pair, distinguishable from the bridged ion pair by the wave number of the 8a v(CC) phenyl ring mode. The calculated structure of the phenylacetonitrile anion in the (PhCHCNLi, CH3Li) mixed dimer or 'Quadac' is very similar to that in the linear ion pair or in the dimer and to that observed by X-ray in (PhCHCNLi, [CH(CH9)2]2NLi) 'Quadac'. The structure of the anion is planar, indicating a charge delocalization from the benzene ring to the -CHCN group. The calculated spectra of the free, mono and dilithiated dianionic species compare well with the experimental ones of the species formed under addition of more than one equivalent of n-BuLi. The structure of the >C-C-CN2- group is very close to that of an imine. The v(CN) bands of the free, mono and dilithiated dianionic species are located at 1912, 1930 and 1890 cm(-1), respectively. The large wave number shift observed between the free monoanion and dianion (approximately 176 cm(-1)), in good accordance with the calculated one (170 cm(-1)) allows differentiating mono and dianionic species. The shifts observed for the 8a and 19a v(CC) phenyl ring modes, although much smaller, also allows discriminating the different species. These small shifts indicate a small variation of the electronic delocalization in the benzene ring in agreement with the calculations.
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34
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Carlier PR, Madura JD. Effective computational modeling of constitutional isomerism and aggregation states of explicit solvates of lithiated phenylacetonitrile. J Org Chem 2002; 67:3832-40. [PMID: 12027700 DOI: 10.1021/jo0255633] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present the first calculations which accurately account for the position of metalation and aggregation state of lithiated nitriles. Solvation is found to be a key determinant of structure. Five known solvates of lithiated phenylacetonitrile were examined computationally to determine the minimum level of theory required to reproduce the observed X-ray and multinuclear NMR structures. In all cases Hartree-Fock 3-21G energies of explicit solvates calculated at PM3 geometries correctly predict the observed N-lithiated constitutional isomer. Selected density functional theory (B3LYP/6-31+G*//PM3) energy calculations reproduce this trend. We also show that 3-21G//PM3 calculations which do not include explicit solvent molecules, or which include water as a model for diethyl ether, may lead to incorrect predictions of the preferred constitutional isomer. 3-21G//PM3 energies also adequately account for observed aggregation states of the TMEDA, diethyl ether, and THF solvates. Finally, calculations of THF-solvated monomers up to the B3LYP/6-31+G*//B3LYP/6-31+G level indicate a significant (6.8 kcal/mol) preference for N-lithiation.
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Affiliation(s)
- Paul R Carlier
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24060, USA.
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35
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Henderson KW, Kennedy AR, MacDougall DJ, Shanks D. Solid-State and Theoretical Model Structures of Monolithiated (Organosulfonyl)acetonitriles and the Characterization and Reactivity of Their Geminated Dilithio Derivatives. Organometallics 2002. [DOI: 10.1021/om0107845] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kenneth W. Henderson
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, U.K
| | - Alan R. Kennedy
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, U.K
| | - Dugald J. MacDougall
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, U.K
| | - David Shanks
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, U.K
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36
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37
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Mogali S, Darville K, Pratt LM. Ab initio analysis of lithium dimethylaminoborohydride. J Org Chem 2001; 66:2368-73. [PMID: 11281777 DOI: 10.1021/jo001600j] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ab initio calculations were used to determine the equilibrium geometries and energies of lithium dimethylaminoborohydride. Relative energies of the monomeric and dimeric species were calculated in the gas phase and for the dimethyl ether microsolvated molecules. The most stable structure was a dimer in which the lithium and boron atoms were bridged by two hydrogen atoms, similar to the three-center two-electron bonds in diborane. This hydrogen bridging was maintained in the lithium dimethylaminoborohydride bis(dimethyl ether) microsolvate.
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Affiliation(s)
- S Mogali
- Department of Chemistry, Fisk University, Nashville, Tennessee 37208, USA
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38
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Carlier PR, Lo CWS. 7Li/31P NMR Studies of Lithiated Arylacetonitriles in THF−HMPA Solution: Characterization of HMPA-Solvated Monomers, Dimers, and Separated Ion Pairs. J Am Chem Soc 2000. [DOI: 10.1021/ja002318x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Paul R. Carlier
- Contribution from the Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Cedric W.-S. Lo
- Contribution from the Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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39
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Kennedy AR, Mulvey RE, Rowlings RB. Intermetallic Lithium−Magnesium Hexamethyldisilazide: Synthesis and Structure, Discovery of an Oxygen-Centered Variant, and a Reaction with Benzonitrile That Produces a Novel Amidinate Cage Compound with a Trigonal Bipyramidal Li4MgO Core. J Am Chem Soc 1998. [DOI: 10.1021/ja980561e] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alan R. Kennedy
- Contribution from the Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, U.K
| | - Robert E. Mulvey
- Contribution from the Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, U.K
| | - René B. Rowlings
- Contribution from the Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, U.K
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40
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Strzalko T, Seyden-Penne J, Wartski L, Corset J, Castella-Ventura M, Froment F. 1,2- vs 1,4-Regioselectivity of Lithiated Phenylacetonitrile toward α,β-Unsaturated Carbonyl Compounds. 1. Monomer−Dimer Equilibrium of Lithiated Phenylacetonitrile Ion Pairs in Solution and Structure Determination of the Species by Spectroscopic Methods and ab Initio Calculations. Evidence of a Lithium Bridged Monomeric Ion Pair. J Org Chem 1998. [DOI: 10.1021/jo9614497] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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41
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Xiao Z, Timberlake JW. Cerium (III) chloride mediated nitrile aldol reactions: Enhanced diastereoselectivities using a chiral organocerium complex. Tetrahedron 1998. [DOI: 10.1016/s0040-4020(98)00122-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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42
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Enders D, Kirchhoff J, Gerdes P, Mannes D, Raabe G, Runsink J, Boche G, Marsch M, Ahlbrecht H, Sommer H. Structure and Reactivity of Lithiated α-Amino Nitriles. European J Org Chem 1998. [DOI: 10.1002/(sici)1099-0690(199801)1998:1<63::aid-ejoc63>3.0.co;2-h] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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43
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Davies RP, Raithby PR, Snaith R. Lithiierung eines einfachen Amins mitn-Butyllithium in großem Überschuß: überraschende Bildung von (Ph2NLi) · [Ph(C6H4Li)NLi]2 · (nBuLi)2 · (Et2O)4. Angew Chem Int Ed Engl 1997. [DOI: 10.1002/ange.19971091125] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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44
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Rychnovsky SD, Swenson SS. Alkylation and Reductive Decyanation of 4-Cyano-2,2-dimethyl-1,3-dioxanes (Cyanohydrin Acetonides). J Org Chem 1997. [DOI: 10.1021/jo961826f] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Scott D. Rychnovsky
- Department of Chemistry, University of California, Irvine, California, 92697-2025
| | - Sonja S. Swenson
- Department of Chemistry, University of California, Irvine, California, 92697-2025
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45
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Benzyl and heteroarylmethyl carbanions: Structure and substitutent effects. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1068-7394(96)80006-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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46
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Lucht BL, Bernstein MP, Remenar JF, Collum DB. Polydentate Amine and Ether Solvates of Lithium Hexamethyldisilazide (LiHMDS): Relationship of Ligand Structure, Relative Solvation Energy, and Aggregation State. J Am Chem Soc 1996. [DOI: 10.1021/ja9618199] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brett L. Lucht
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Max P. Bernstein
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Julius F. Remenar
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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47
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Krom JA, Streitwieser A. Cesium Ion Pair Acidities of some N,N-Dialkylacetamides and Aggregation of Their Cesium Enolates in Tetrahydrofuran. J Org Chem 1996; 61:6354-6359. [PMID: 11667477 DOI: 10.1021/jo960687z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cesium ion pair acidities are reported of some N,N-dialkylacetamides at 25 degrees C in tetrahydrofuran. The cesium enolates of alpha-arylacetamides are essentially monomeric at concentrations of about 10(-)(4) M, but small amounts of dimers are present for the enolates of N,N-dimethyl- and N,N-diethyl(4-biphenylyl)acetamide (K(dimer) is approximately 400 M(-)(1)). The cesium enolate of N,N-dimethyldiphenylacetamide forms small amounts of dimers, but the dimerization constant of <100 M(-)(1) is near the limit of detection of our methods. The enolate of N,N-diethylacetamide has an average aggregation number of 3.3, consistent with a mixture of dimers and tetramers. The cesium ion pair pKs of the alpha-arylacetamides are about 25-26, and that of N,N-diethylacetamide is greater than 33.7. The acidity data are in good agreement with measurements that have been reported in the literature for similar systems.
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Affiliation(s)
- James A. Krom
- College of Chemistry, University of California, Berkeley, California 94720-1460
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