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Jansen-van Vuuren RD, Liu S, Miah MAJ, Cerkovnik J, Košmrlj J, Snieckus V. The Versatile and Strategic O-Carbamate Directed Metalation Group in the Synthesis of Aromatic Molecules: An Update. Chem Rev 2024; 124:7731-7828. [PMID: 38864673 PMCID: PMC11212060 DOI: 10.1021/acs.chemrev.3c00923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 04/26/2024] [Accepted: 05/08/2024] [Indexed: 06/13/2024]
Abstract
The aryl O-carbamate (ArOAm) group is among the strongest of the directed metalation groups (DMGs) in directed ortho metalation (DoM) chemistry, especially in the form Ar-OCONEt2. Since the last comprehensive review of metalation chemistry involving ArOAms (published more than 30 years ago), the field has expanded significantly. For example, it now encompasses new substrates, solvent systems, and metalating agents, while conditions have been developed enabling metalation of ArOAm to be conducted in a green and sustainable manner. The ArOAm group has also proven to be effective in the anionic ortho-Fries (AoF) rearrangement, Directed remote metalation (DreM), iterative DoM sequences, and DoM-halogen dance (HalD) synthetic strategies and has been transformed into a diverse range of functionalities and coupled with various groups through a range of cross-coupling (CC) strategies. Of ultimate value, the ArOAm group has demonstrated utility in the synthesis of a diverse range of bioactive and polycyclic aromatic compounds for various applications.
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Affiliation(s)
- Ross D. Jansen-van Vuuren
- Department
of Chemistry, Queen’s University, Chernoff Hall, 9 Bader Lane, Kingston, Ontario K7K 2N1, Canada
- Faculty
of Chemistry and Chemical Technology, University
of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Susana Liu
- Department
of Chemistry, Queen’s University, Chernoff Hall, 9 Bader Lane, Kingston, Ontario K7K 2N1, Canada
| | - M. A. Jalil Miah
- Department
of Chemistry, Rajshahi University, Rajshahi-6205, Bangladesh
| | - Janez Cerkovnik
- Faculty
of Chemistry and Chemical Technology, University
of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Janez Košmrlj
- Faculty
of Chemistry and Chemical Technology, University
of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Victor Snieckus
- Department
of Chemistry, Queen’s University, Chernoff Hall, 9 Bader Lane, Kingston, Ontario K7K 2N1, Canada
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2
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Belmonte-Sánchez E, García-López J, Navarro Y, Iglesias MJ, Fernández I, López-Ortiz F. Crystal, Solution, and Computational Study of the Structure of Ortho-Lithium N,N-Diisopropyl-P,P-Diphenylphosphinothioic Amide. Chemistry 2024; 30:e202303785. [PMID: 38134366 DOI: 10.1002/chem.202303785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 12/24/2023]
Abstract
The first crystal structure of an ortho-lithium phosphinothioic amide complexed with tetramethylethylenediamine 12 is reported. The complex consists of a spirane in which the spiro-lithium is N,N- and C,S-chelated by the diamine and organophosphorus ligands, respectively. The analogous ortho anion 14 obtained by Sn(IV)/Li transmetallation in THF has also been synthesized. Nuclear magnetic resonance study of both anions showed that they exist as monomers in solution and are involved in dynamic processes including the restricted rotation around the P-N bond. 14 is converted at room temperature by nucleophilic cyclization to the dearomatized anion 15, which evolves after a few hours to the benzophosphindole sulfide 16. Density functional theory calculations supported the aggregation state in solution and were used to explore the conformational space of anion 12, the mechanism of ortho-lithiation directed by P(X)-N (X=O, S) groups, and the mechanism of formation of 15.
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Affiliation(s)
- Eva Belmonte-Sánchez
- Área de Química Orgánica, Centro de Investigación CIAIMBITAL, Universidad de Almería, 04120, Almería, Spain
| | - Jesús García-López
- Área de Química Orgánica, Centro de Investigación CIAIMBITAL, Universidad de Almería, 04120, Almería, Spain
| | - Yolanda Navarro
- Área de Química Orgánica, Centro de Investigación CIAIMBITAL, Universidad de Almería, 04120, Almería, Spain
| | - María José Iglesias
- Área de Química Orgánica, Centro de Investigación CIAIMBITAL, Universidad de Almería, 04120, Almería, Spain
| | - Ignacio Fernández
- Área de Química Orgánica, Centro de Investigación CIAIMBITAL, Universidad de Almería, 04120, Almería, Spain
| | - Fernando López-Ortiz
- Área de Química Orgánica, Centro de Investigación CIAIMBITAL, Universidad de Almería, 04120, Almería, Spain
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3
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Malik M, Senatore R, Langer T, Holzer W, Pace V. Base-mediated homologative rearrangement of nitrogen-oxygen bonds of N-methyl- N-oxyamides. Chem Sci 2023; 14:10140-10146. [PMID: 37772102 PMCID: PMC10530184 DOI: 10.1039/d3sc03216g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 08/26/2023] [Indexed: 09/30/2023] Open
Abstract
Due to the well known reactivity of C(O)-N functionalities towards canonical C1-homologating agents (e.g. carbenoids, diazomethane, ylides), resulting in the extrusion of the N-centered fragment en route to carbonyl compounds, formal C1-insertions within N-O bonds still remain obscure. Herein, we document the homologative transformation of N-methyl-N-oxyamides - with high tolerance for diverse O-substituents - into N-acyl-N,O-acetals. Under controlled basic conditions, the N-methyl group of the same starting materials acts as a competent precursor of the methylene synthon required for the homologation. The logic is levered on the formation of an electrophilic iminium ion (via N-O heterolysis) susceptible to nucleophilic attack by the alkoxide previously expulsed. The procedure documents genuine chemocontrol and flexibility, as judged by the diversity of substituents placed on both amide and nitrogen linchpins. The mechanistic rationale was validated through experiments conducted on D-labeled materials which unambiguously attributed the origin of the methylene fragment to the N-methyl group of the starting compounds.
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Affiliation(s)
- Monika Malik
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Raffaele Senatore
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Thierry Langer
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Wolfgang Holzer
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Vittorio Pace
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
- Department of Chemistry, University of Turin Via Giuria 7 10125 Turin Italy
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4
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Woltornist RA, Collum DB. Aggregation and Solvation of Sodium Hexamethyldisilazide: Across the Solvent Spectrum. J Org Chem 2021; 86:2406-2422. [PMID: 33471993 PMCID: PMC8011853 DOI: 10.1021/acs.joc.0c02546] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report solution structures of sodium hexamethyldisilazide (NaHMDS) solvated by >30 standard solvents (ligands). These include: toluene, benzene, and styrene; triethylamine and related trialkylamines; pyrrolidine as a representative dialkylamine; dialkylethers including THF, tert-butylmethyl ether, and diethyl ether; dipolar ligands such as DMF, HMPA, DMSO, and DMPU; a bifunctional dipolar ligand nonamethylimidodiphosphoramide (NIPA); polyamines N,N,N',N'-tetramethylenediamine (TMEDA), N,N,N',N″,N″-pentamethyldiethylenetriamine (PMDTA), N,N,N',N'-tetramethylcyclohexanediamine (TMCDA), and 2,2'-bipyridine; polyethers 12-crown-4, 15-crown-5, 18-crown-6, and diglyme; 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane ([2.2.2] cryptand); and tris[2-(2-methoxyethoxy)ethyl]amine (TDA-1). Combinations of 1H, 13C, 15N, and 29Si NMR spectroscopies, the method of continuous variations, X-ray crystallography, and density functional theory (DFT) computations reveal ligand-modulated aggregation to give mixtures of dimers, monomers, triple ions, and ion pairs. 15N-29Si coupling constants distinguish dimers and monomers. Solvation numbers are determined by a combination of solvent titrations, observed free and bound solvent in the slow exchange limit, and DFT computations. The relative abilities of solvents to compete in binary mixtures often match that predicted by conventional wisdom but with some exceptions and evidence of both competitive and cooperative (mixed) solvation. Crystal structures of a NaHMDS cryptate ion pair and a 15-crown-5-solvated monomer are included. Results are compared with those for lithium hexamethyldisilazide, lithium diisopropylamide, and sodium diisopropylamide.
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Affiliation(s)
- Ryan A Woltornist
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - David B Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
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5
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Abstract
Solution characterizations and ligand binding constants were determined for n-butyllithium in hydrocarbon and ethereal solvents using diffusion-ordered NMR. In hydrocarbon solvents, n-butyllithium exists primarily as an octamer at -40 °C and deaggregates to a hexamer when the temperature is increased. In the presence of THF or diethyl ether, n-butyllithium exists predominantly as a tetra-solvated tetramer and deaggregates to a tetra-solvated dimer in the presence of a large excess or neat THF. The ligand binding constants for the tetra-solvated tetramers were measured using 1H NMR/DOSY titration.
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Affiliation(s)
- Onkei Tai
- Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States
| | - Russell Hopson
- Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States
| | - Paul G Williard
- Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States
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6
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Tai O, Hopson R, Williard PG. Ligand Binding Constants to Lithium Hexamethyldisilazide Determined by Diffusion-Ordered NMR Spectroscopy. J Org Chem 2017; 82:6223-6231. [PMID: 28562035 DOI: 10.1021/acs.joc.7b00800] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the direct measurement of ligand-binding constants of organolithium complexes using a 1H NMR/diffusion-ordered NMR spectroscopy (DOSY) titration technique. Lithium hexamethyldisilazide complexes with ethereal and ester donor ligands (THF, diethyl ether, MTBE, THP, tert-butyl acetate) are characterized using 1H NMR and X-ray crystallography. Their aggregation and solvation states are confirmed using diffusion coefficient-formula weight correlation analysis, and the 1H NMR/DOSY titration technique is applied to obtain their binding constants. Our work suggests that steric hindrance of ethereal ligands plays an important role in the aggregation, solvation, and reactivity of these complexes. It is noteworthy that diffusion methodology is utilized to obtain binding constants.
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Affiliation(s)
- Onkei Tai
- Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States
| | - Russell Hopson
- Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States
| | - Paul G Williard
- Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States
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7
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Ojeda-Amador AI, Martínez-Martínez AJ, Kennedy AR, Armstrong DR, O'Hara CT. Monodentate coordination of the normally chelating chiral diamine (R,R)-TMCDA. Chem Commun (Camb) 2016; 53:324-327. [PMID: 27958607 DOI: 10.1039/c6cc07190b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
After isolating an unusual binuclear, but monosolvated NaHMDS complex [{(R,R)-TMCDA}·(NaHMDS)2]∞ which polymerises via intermolecular electrostatic NaMeHMDS interactions, further (R,R)-TMCDA was added to produce the discrete binuclear amide [{κ2-(R,R)-TMCDA}·(NaHMDS)2{κ1-(R,R)-TMCDA}], whose salient feature is the unique monodentate coordination of one of the chiral diamine ligands.
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Affiliation(s)
- Ana I Ojeda-Amador
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
| | - Antonio J Martínez-Martínez
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
| | - Alan R Kennedy
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
| | - David R Armstrong
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
| | - Charles T O'Hara
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
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8
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Cicco L, Addante V, Temperini A, Donau CA, Karaghiosoff K, Perna FM, Capriati V. Toward Customized Tetrahydropyran Derivatives through Regioselective α-Lithiation and Functionalization of 2-Phenyltetrahydropyran. European J Org Chem 2016. [DOI: 10.1002/ejoc.201600365] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Luciana Cicco
- Dipartimento di Farmacia-Scienze del Farmaco; Università di Bari “Aldo Moro”; Consorzio C.I.N.M.P.I.S.; Via E. Orabona 4 70125 Bari Italy
| | - Valeria Addante
- Dipartimento di Farmacia-Scienze del Farmaco; Università di Bari “Aldo Moro”; Consorzio C.I.N.M.P.I.S.; Via E. Orabona 4 70125 Bari Italy
| | - Andrea Temperini
- Dipartimento di Scienze Farmaceutiche; Università di Perugia; Via del Liceo 1 06123 Perugia Italy
| | - Carsten Adam Donau
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13, Haus F 81377 München Germany
| | - Konstantin Karaghiosoff
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13, Haus F 81377 München Germany
| | - Filippo Maria Perna
- Dipartimento di Farmacia-Scienze del Farmaco; Università di Bari “Aldo Moro”; Consorzio C.I.N.M.P.I.S.; Via E. Orabona 4 70125 Bari Italy
| | - Vito Capriati
- Dipartimento di Farmacia-Scienze del Farmaco; Università di Bari “Aldo Moro”; Consorzio C.I.N.M.P.I.S.; Via E. Orabona 4 70125 Bari Italy
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9
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Bruneau A, Liou L, Collum DB. Solution structures of lithium amino alkoxides used in highly enantioselective 1,2-additions. J Am Chem Soc 2014; 136:2885-91. [PMID: 24471766 PMCID: PMC3985715 DOI: 10.1021/ja412210d] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Indexed: 01/25/2023]
Abstract
Lithium ephedrates and norcarane-derived lithium amino alkoxides used to effect highly enantioselective 1,2-additions on large scales have been characterized in toluene and tetrahydrofuran. The method of continuous variations in conjunction with (6)Li NMR spectroscopy reveals that the lithium amino alkoxides are tetrameric. In each case, low-temperature (6)Li NMR spectra show stereoisomerically pure homoaggregates displaying resonances consistent with an S4-symmetric cubic core rather than the alternative D2d core. These assignments are supported by density functional theory computations and conform to X-ray crystal structures. Slow aggregate exchanges are discussed in the context of amino alkoxides as chiral auxiliaries.
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Affiliation(s)
- Angela
M. Bruneau
- Department of Chemistry and
Chemical Biology Baker Laboratory, Cornell
University, Ithaca, New York 14853-1301, United States
| | - Lara Liou
- Department of Chemistry and
Chemical Biology Baker Laboratory, Cornell
University, Ithaca, New York 14853-1301, United States
| | - David B. Collum
- Department of Chemistry and
Chemical Biology Baker Laboratory, Cornell
University, Ithaca, New York 14853-1301, United States
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10
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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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11
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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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12
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Tomasevich LL, Collum DB. Structure determination using the method of continuous variation: lithium phenolates solvated by protic and dipolar aprotic ligands. J Org Chem 2013; 78:7498-507. [PMID: 23806055 PMCID: PMC3759316 DOI: 10.1021/jo401080n] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The method of continuous variation (MCV) was used in conjunction with (6)Li NMR spectroscopy to characterize four lithium phenolates solvated by a range of solvents, including N,N,N',N'-tetramethylethylenediamine, Et2O, pyridine, protic amines, alcohols, and highly dipolar aprotic solvents. Dimers, trimers, and tetramers were observed, depending on the precise lithium phenolate-solvent combinations. Competition experiments (solvent swaps) provide insights into the relative propensities toward mixed solvation.
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Affiliation(s)
- Laura L. Tomasevich
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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13
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Su C, Hopson R, Williard PG. Characterization of Hexameric and Octameric
sec
‐Butyllithium/
sec
‐Butoxide Mixed Aggregates. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201300749] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Chicheung Su
- Department of Chemistry, Brown University, 324 Brook Street, Providence, RI 02912, USA
| | - Russell Hopson
- Department of Chemistry, Brown University, 324 Brook Street, Providence, RI 02912, USA
| | - Paul G. Williard
- Department of Chemistry, Brown University, 324 Brook Street, Providence, RI 02912, USA
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14
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Mechanism of the Deprotonation Reaction of Alkyl Benzyl Ethers withn-Butyllithium. Chemistry 2013; 19:9677-85. [DOI: 10.1002/chem.201204467] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 04/15/2013] [Indexed: 11/07/2022]
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15
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De Vries TS, Bruneau AM, Liou LR, Subramanian H, Collum DB. Azaaldol condensation of a lithium enolate solvated by N,N,N',N'-tetramethylethylenediamine: dimer-based 1,2-addition to imines. J Am Chem Soc 2013; 135:4103-9. [PMID: 23413774 PMCID: PMC3715612 DOI: 10.1021/ja400345c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The lithium enolate of tert-amylacetate solvated by N,N,N',N'-tetramethylethylenediamine (TMEDA) is shown to be a doubly chelated dimer. Adding the dimeric enolate to 4-fluorobenzaldehyde-N-phenylimine affords an N-lithiated β-amino ester shown to be monomeric using (6)Li and (15)N NMR spectroscopies. Rate studies using (19)F NMR spectroscopy reveal reaction orders consistent with a transition structure of stoichiometry [(ROLi)2(TMEDA)2(imine)](‡). Density functional theory computations explore several possible dimer-based transition structures with monodentate and bidentate coordination of TMEDA. Supporting rate studies using trans-N,N,N',N'-1,2-tetramethylcyclohexanediamine showing analogous rates and rate law suggest that TMEDA is fully chelated.
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Affiliation(s)
- Timothy S. De Vries
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Angela M. Bruneau
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Lara R. Liou
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | | | - David B. Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
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16
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Casimiro M, Oña-Burgos P, Meyer J, Styra S, Kuzu I, Breher F, Fernández I. On the Solution Behaviour of Benzyllithium⋅(−)-Sparteine Adducts and Related Lithium Organyls - A Case Study on Applying7Li,15N{1H} HMQC and Further NMR Methods, Including Some Investigation into Asymmetric Synthesis. Chemistry 2012. [DOI: 10.1002/chem.201202346] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Heuclin H, Le Goff XF, Mézailles N. Mixed (PS/PO)-Stabilized Geminal Dianion: Facile Diastereoselective Intramolecular CH Activations by a Related Ruthenium-Carbene Complex. Chemistry 2012; 18:16136-44. [DOI: 10.1002/chem.201202680] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Indexed: 11/07/2022]
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18
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Ertürk E, Tezeren MA, Atalar T, Tilki T. Regioselective ring-opening of epoxides with ortho-lithioanisoles catalyzed by BF3·OEt2. Tetrahedron 2012. [DOI: 10.1016/j.tet.2012.05.116] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Praz J, Guénée L, Aziz S, Berkessel A, Alexakis A. Evaluation of the Chiral DIANANE Backbone as Ligand for Organolithium Reagents. Adv Synth Catal 2012. [DOI: 10.1002/adsc.201101016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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Borowska E, Durka K, Luliński S, Serwatowski J, Woźniak K. On the Directing Effect of Boronate Groups in the Lithiation of Boronated Thiophenes. European J Org Chem 2012. [DOI: 10.1002/ejoc.201101764] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Popescu AR, Musteti AD, Ferrer-Ugalde A, Viñas C, Núñez R, Teixidor F. Influential Role of Ethereal Solvent on Organolithium Compounds: The Case of Carboranyllithium. Chemistry 2012; 18:3174-84. [DOI: 10.1002/chem.201102626] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Indexed: 01/27/2023]
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22
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el Hajjouji H, Belmonte E, García-López J, Fernández I, Iglesias MJ, Roces L, García-Granda S, El Laghdach A, López Ortiz F. Transformations of diphenylphosphinothioic acid tertiary amides mediated by directed ortho metallation. Org Biomol Chem 2012; 10:5647-58. [DOI: 10.1039/c2ob25395j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Scholz R, Hellmann G, Rohs S, Özdemir D, Raabe G, Vermeeren C, Gais HJ. Enantioselective Synthesis, Configurational Stability, and Reactivity of Lithium α-tert-Butylsulfonyl Carbanion Salts. European J Org Chem 2010. [DOI: 10.1002/ejoc.201000410] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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24
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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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25
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Kizirian J. Mechanism and Stereochemical Features in Asymmetric Deprotonation Using RLi/(–)‐Sparteine Bases. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/9783906390628.ch6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Postigo L, Bellarosa L, Sánchez-Nieves J, Royo P, Lledós A, Mosquera MEG. Dinuclear Dicyclopentadienyl Titanium Complexes with Bridging Cyclopentadienylsiloxo Ligands. Organometallics 2010. [DOI: 10.1021/om900938m] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lorena Postigo
- Departamento de Química Inorgánica, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares (Madrid), Spain
| | - Luca Bellarosa
- Departament de Química, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Spain
| | - Javier Sánchez-Nieves
- Departamento de Química Inorgánica, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares (Madrid), Spain
| | - Pascual Royo
- Departamento de Química Inorgánica, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares (Madrid), Spain
| | - Agustí Lledós
- Departament de Química, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Spain
| | - Marta E. G. Mosquera
- Departamento de Química Inorgánica, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares (Madrid), Spain
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27
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De Vries TS, Goswami A, Liou LR, Gruver JM, Jayne E, Collum DB. Lithium phenolates solvated by tetrahydrofuran and 1,2-dimethoxyethane: structure determination using the method of continuous variation. J Am Chem Soc 2009; 131:13142-54. [PMID: 19702308 PMCID: PMC2752606 DOI: 10.1021/ja9047784] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The method of continuous variation in conjunction with (6)Li NMR spectroscopy was used to characterize lithium phenolates solvated by tetrahydrofuran and 1,2-dimethoxyethane. The strategy relies on the formation of ensembles of homo- and heteroaggregated phenolates. The symmetries and concentration dependencies of the heteroaggregates attest to the aggregation numbers of the homoaggregates. The structurally diverse phenols afford substrate- and solvent-dependent combinations of lithium phenolate monomers, dimers, trimers, tetramers, and pentamers. We discuss the refinement of protocols for characterizing O-lithiated species. Computational studies examine further the substituent and solvent dependencies of aggregation.
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Affiliation(s)
- Timothy S De Vries
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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28
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29
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Würthwein EU, Hoppe D. Enantiotopos-Differentiating (−)-Sparteine-Mediated γ-Deprotonation of 1-Alkenyl Carbamates: DFT Calculations Verify the Observed Stereoselectivity. J Org Chem 2008; 73:9055-60. [DOI: 10.1021/jo8018158] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ernst-Ulrich Würthwein
- Organisch-Chemisches Institut der Westfälischen Wilhelms-Universität Münster, Corrensstraβe 40, D-48149 Münster, Germany
| | - Dieter Hoppe
- Organisch-Chemisches Institut der Westfälischen Wilhelms-Universität Münster, Corrensstraβe 40, D-48149 Münster, Germany
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30
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Gessner VH, Strohmann C. Lithiation of TMEDA and its Higher Homologous TEEDA: Understanding Observed α- and β-Deprotonation. J Am Chem Soc 2008; 130:14412-3. [DOI: 10.1021/ja8058205] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Viktoria H. Gessner
- Anorganische Chemie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227 Dortmund, Germany
| | - Carsten Strohmann
- Anorganische Chemie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227 Dortmund, Germany
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31
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Strohmann C, Gessner VH. Crystal structures of n-BuLi adducts with (R,R)-TMCDA and the consequences for the deprotonation of benzene. J Am Chem Soc 2008; 130:11719-25. [PMID: 18686951 DOI: 10.1021/ja8017187] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Combinations of organolithium compounds and diamine bases have become a powerful tool in synthetic chemistry. Because of the structure-reactivity relationship, the elucidation of reaction mechanisms of these reagents is strongly connected with the structural determination of intermediate species. In mixtures of the diamine TMCDA (N,N,N',N'-tetramethylcyclohexane-1,2-diamine) and n-butyllithium, two different structures, the dimeric [n-BuLi x (R,R)-TMCDA]2 and the aggregate [(n-BuLi)2 x (R,R)-TMCDA]2, can be isolated, depending on the n-BuLi/TMCDA ratio. Thereby, [(n-BuLi)2 x (R,R)-TMCDA]2 is a rare example of an organolithium compound with a ladder arrangement of the central four-membered Li-C-Li-C rings. Two isomers of the ladder structure are formed in the crystal by changing from the enantiomerically pure to racemic TMCDA. As n-BuLi/TMCDA mixtures are also able to deprotonate benzene, these structures give hint to possible mechanisms. Supported by theoretical studies, transition states based on the dimer, the ladder structure, and a hypothetical monomer are discussed.
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Affiliation(s)
- Carsten Strohmann
- Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
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32
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Liou LR, McNeil AJ, Ramirez A, Toombes GES, Gruver JM, Collum DB. Lithium enolates of simple ketones: structure determination using the method of continuous variation. J Am Chem Soc 2008; 130:4859-68. [PMID: 18336025 PMCID: PMC2636850 DOI: 10.1021/ja7100642] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The method of continuous variation in conjunction with 6Li NMR spectroscopy was used to characterize lithium enolates derived from 1-indanone, cyclohexanone, and cyclopentanone in solution. The strategy relies on forming ensembles of homo- and heteroaggregated enolates. The enolates form exclusively chelated dimers in N,N,N',N'-tetramethylethylenediamine and cubic tetramers in tetrahydrofuran and 1,2-dimethoxyethane.
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Affiliation(s)
- Lara R Liou
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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33
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Riggs JC, Ramirez A, Cremeens ME, Bashore CG, Candler J, Wirtz MC, Coe JW, Collum DB. Structural and Rate Studies of the Formation of Substituted Benzynes. J Am Chem Soc 2008; 130:3406-12. [DOI: 10.1021/ja0754655] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jason C. Riggs
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, and Pfizer Global Research and Development, Groton Laboratories, Pfizer, Inc., Groton, Connecticut 06340
| | - Antonio Ramirez
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, and Pfizer Global Research and Development, Groton Laboratories, Pfizer, Inc., Groton, Connecticut 06340
| | - Matthew E. Cremeens
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, and Pfizer Global Research and Development, Groton Laboratories, Pfizer, Inc., Groton, Connecticut 06340
| | - Crystal G. Bashore
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, and Pfizer Global Research and Development, Groton Laboratories, Pfizer, Inc., Groton, Connecticut 06340
| | - John Candler
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, and Pfizer Global Research and Development, Groton Laboratories, Pfizer, Inc., Groton, Connecticut 06340
| | - Michael C. Wirtz
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, and Pfizer Global Research and Development, Groton Laboratories, Pfizer, Inc., Groton, Connecticut 06340
| | - Jotham W. Coe
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, and Pfizer Global Research and Development, Groton Laboratories, Pfizer, Inc., Groton, Connecticut 06340
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, and Pfizer Global Research and Development, Groton Laboratories, Pfizer, Inc., Groton, Connecticut 06340
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34
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Godenschwager PF, Collum DB. Lithium Hexamethyldisilazide-Mediated Enolizations: Influence of Chelating Ligands and Hydrocarbon Cosolvents on the Rates and Mechanisms. J Am Chem Soc 2007; 129:12023-31. [PMID: 17850084 DOI: 10.1021/ja074018m] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enolizations of 2-methylcyclohexanone by lithium hexamethyldisilazide (LiHMDS) in the presence of three chelating ligands--trans-N,N,N',N'-tetramethylcyclohexanediamine, N,N,N',N'-tetramethylethylenediamine, and dimethoxyethane--reveal an approximate 40-fold range of rates. NMR spectroscopic analyses and rate studies reveal isostructural transition structures based on monomeric LiHMDS for the diamines. Rate studies of LiHMDS/dimethoxyethane-mediated enolizations implicate a substantial number of monomer- and dimer-based mechanisms. The rate laws vary for the three ligands because of ligand-dependent structural differences in both the reactants and the transition structures. The importance of LiHMDS-ketone complexes and the role of hydrocarbon cosolvents are discussed.
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Affiliation(s)
- Peter F Godenschwager
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University Ithaca, New York 14853-1301, USA
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35
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Strohmann C, Gessner VH. Crystal Structures of the Chiral Diamine (R,R)-TMCDA with the Commonly Used Alkyllithium Bases Methyllithium, iso-Propyllithium, and sec-Butyllithium. J Am Chem Soc 2007; 129:8952-3. [PMID: 17595089 DOI: 10.1021/ja072970t] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carsten Strohmann
- Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
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36
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Pratt LM, Truhlar DG, Cramer CJ, Kass SR, Thompson JD, Xidos JD. Aggregation of Alkyllithiums in Tetrahydrofuran. J Org Chem 2007; 72:2962-6. [PMID: 17358078 DOI: 10.1021/jo062557o] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Density functional theory was used to examine the solvation number and aggregation state of several alkyllithium compounds in clusters with tetrahydrofuran molecules coordinated to each lithium atom. We then made the microsolvation approximation and approximated the bulk free energy of solvation by the free energy of clustering with solvent molecules in the gas phase. The trends in the computed results are in reasonable agreement with the available experimental data.
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Affiliation(s)
- Lawrence M Pratt
- Department of Chemistry, Fisk University, Nashville, Tennessee 37208, USA.
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37
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38
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Chadwick ST, Ramirez A, Gupta L, Collum DB. n-Butyllithium/N,N,N‘,N‘-Tetramethylethylenediamine-Mediated Ortholithiations of Aryl Oxazolines: Substrate-Dependent Mechanisms. J Am Chem Soc 2007; 129:2259-68. [PMID: 17269777 DOI: 10.1021/ja068057u] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
n-Butyllithium/N,N,N',N'-tetramethylethylenediamine-mediated ortholithiations of aryloxazolines are described. Methyl substituents on the aryloxazoline and substituents at the meta position of the arenes (methoxy, oxazolinyl, and fluoro) influence the rates and the mechanisms. Monomer- and dimer-based reactions are implicated. Density functional calculations probe details of the mechanism and suggest the origins of cooperative effects in meta-substituted aryl oxazolines.
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Affiliation(s)
- Scott T Chadwick
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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39
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Sott R, Håkansson M, Hilmersson G. Studies of Complexes between Phenyllithium and (−)-Sparteine in Ether Solutions. Organometallics 2006. [DOI: 10.1021/om050872f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Richard Sott
- Department of Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden
| | - Mikael Håkansson
- Department of Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden
| | - Göran Hilmersson
- Department of Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden
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40
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Singh KJ, Collum DB. Lithium Diisopropylamide-Mediated Ortholithiation and Anionic Fries Rearrangement of Aryl Carbamates: Role of Aggregates and Mixed Aggregates. J Am Chem Soc 2006; 128:13753-60. [PMID: 17044703 DOI: 10.1021/ja064655x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Structural and mechanistic studies of the lithium diisopropylamide (LDA)-mediated anionic Fries rearrangements of aryl carbamates are described. Substituents at the meta position of the arene (H, OMe, F) and the dialkylamino moiety of the carbamate (Me(2)N, Et(2)N, and i-Pr(2)N) markedly influence the relative rates of ortholithiation and subsequent Fries rearrangement. Structural studies using (6)Li and (15)N NMR spectroscopies on samples derived from [(6)Li,(15)N]LDA reveal an LDA dimer, LDA dimer-arene complexes, an aryllithium monomer, LDA-aryllithium mixed dimers, an LDA-lithium phenolate mixed dimer, and homoaggregated lithium phenolates. The highly insoluble phenolate was characterized as a dimer by X-ray crystallography. Rate studies show monomer- and dimer-based ortholithiations as well as monomer- and mixed dimer-based Fries rearrangements. Density functional theory computational studies probe experimentally elusive structural and mechanistic details.
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Affiliation(s)
- Kanwal Jit Singh
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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41
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Goldfuss B, Steigelmann M, Löschmann T, Schilling G, Rominger F. A dispensable methoxy group? Phenyl fencholate as a chiral modifier of n-butyllithium. Chemistry 2006; 11:4019-23. [PMID: 15861473 DOI: 10.1002/chem.200500158] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Phenyl fenchol forms a 3:1 aggregate with n-butyllithium (3-BuLi), showing unique lithium-HC agostic interactions both in toluene solution (1H,7Li-HOESY) and in the solid state (X-ray analysis). Although methoxy-lithium coordination is characteristic for many mixed aggregates of anisyl fencholates with n-butyllithium, endo-methyl coordination to lithium ions compensates for the missing methoxy groups in 3-BuLi. This gives rise to a different orientation of the fenchane moiety, encapsulating and chirally modifying the butylide unit.
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Affiliation(s)
- B Goldfuss
- Institut für Organische Chemie, Universität zu Köln, Greinstrasse 4, 50939 Köln, Germany.
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42
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Ramirez A, Sun X, Collum DB. Lithium Diisopropylamide-Mediated Enolization: Catalysis by Hemilabile Ligands. J Am Chem Soc 2006; 128:10326-36. [PMID: 16881665 DOI: 10.1021/ja062147h] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Structural, kinetic, and computational studies reveal the mechanistic complexities of a lithium diisopropylamide (LDA)-mediated ester enolization. Hemilabile amino ether MeOCH2CH2NMe2, binding as an eta1 (ether-bound) ligand in the reactant and as an eta2 (chelating) ligand in the transition structure, accelerates the enolization 10,000-fold compared with n-BuOMe. At the onset of the reaction, a dimer-based enolization prevails. As the reaction proceeds, significantly less reactive LDA-enolate mixed dimers appear and divert the reaction through monomer- and mixed dimer-based pathways. The mechanistic and computational investigations lead to a proof-of-principle ligand-catalyzed enolization in which an ancillary ligand allows the catalytic ligand to re-enter the catalytic cycle.
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Affiliation(s)
- Antonio Ramirez
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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43
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Qu B, Collum DB. Structure of n-Butyllithium in Mixtures of Ethers and Diamines: Influence of Mixed Solvation on 1,2-Additions to Imines. J Am Chem Soc 2006; 128:9355-60. [PMID: 16848470 DOI: 10.1021/ja0609654] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
n-BuLi in diamine/dialkyl ether mixtures forms ensembles of hetero- and homosolvated dimers. Solutions in TMEDA/THF (TMEDA = N,N,N',N'-tetramethylethylenediamine) are not amenable to detailed investigation because of rapid ligand exchange. TMCDA/THF mixtures (TMCDA = trans-N,N,N',N'-tetramethylcyclohexanediamine) afford clean assignments for a mixture of homo- and heterosolvated dimers but demonstrate poor control over structure. TMCDA/tetrahydropyran (THP) mixtures and TMEDA/Et2O mixtures afford clean structural assignments as well as excellent structural control. Rate studies of the 1,2-addition of n-BuLi using TMCDA/THP mixtures reveal cooperative solvation in which both THP and TMCDA coordinate to lithium at the monomer- and dimer-based transition structures. The two mechanisms are affiliated with markedly different stereochemistries of the 1,2-addition to imines. The results show strong parallels with previous investigations of 1,2-additions in TMEDA/Et2O mixtures.
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Affiliation(s)
- Bo Qu
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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44
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Qu B, Collum DB. Addition of n-Butyllithium to an Aldimine: Role of Chelation, Aggregation, and Cooperative Solvation. J Am Chem Soc 2005; 127:10820-1. [PMID: 16076174 DOI: 10.1021/ja0519987] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rate studies of the addition of n-BuLi in the presence of TMEDA to potentially chelating aldimines are consistent with a combination of monomer- and dimer-based mechanisms. Using mixtures of TMEDA and Et2O reveals cooperative solvation in which both Et2O and TMEDA coordinate to lithium at the monomer- and dimer-based transition structures. The four discrete mechanisms are affiliated with markedly different stereochemistries of the 1,2-addition.
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Affiliation(s)
- Bo Qu
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA
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45
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Ma Y, Lobkovsky E, Collum DB. BF3-mediated additions of organolithiums to ketimines: X-ray crystal structures of BF3-ketimine complexes. J Org Chem 2005; 70:2335-7. [PMID: 15760225 DOI: 10.1021/jo0480895] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text] Additions of lithium acetylides and n-BuLi to N-alkyl ketimines mediated by BF(3)-Et(2)O in THF afford hindered tert-alkylamines in moderate to good yields. Stereochemical results and crystal structures of three BF(3)-imine complexes suggest that allylic strain strongly influences conformation and may be an important determinant of reactivity and selectivity.
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Affiliation(s)
- Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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46
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Ramírez A, Candler J, Bashore CG, Wirtz MC, Coe JW, Collum DB. Formation of Benzynes from 2,6-Dihaloaryllithiums: Mechanistic Basis of the Regioselectivity. J Am Chem Soc 2004; 126:14700-1. [PMID: 15535677 DOI: 10.1021/ja044899m] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The key elimination step for the formation of 3-chloro- and 3-fluorobenzyne from 2-chloro-6-fluorophenyllithium displays a pronounced solvent-dependent regioselectivity. 6Li and 13C NMR spectroscopic studies on 2-chloro-6-fluorophenyllithium reveal a single monomeric aryllithium, suggested by DFT computational studies to be a trisolvate. Rate studies indicate that the elimination of LiCl and LiF proceeds via trisolvated and disolvated monomers, respectively.
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Affiliation(s)
- Antonio Ramírez
- Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
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47
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O'Brien P, Wiberg KB, Bailey WF, Hermet JPR, McGrath MJ. An Experimental and Computational Study of the Enantioselective Lithiation of N-Boc-pyrrolidine Using Sparteine-like Chiral Diamines. J Am Chem Soc 2004; 126:15480-9. [PMID: 15563176 DOI: 10.1021/ja046834p] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The enantioselective lithiation of N-Boc-pyrrolidine using sec-butyllithium and isopropyllithium in the presence of sparteine-like diamines has been studied experimentally and computationally at various theoretical levels through to B3P86/6-31G*. Of the (-)-cytisine-derived diamines (N-Me, N-Et, N-(n)Bu, N-CH(2)(t)Bu, N-(i)Pr) studied experimentally, the highest enantioselectivity (er 95:5) was observed with the least sterically hindered N-Me-substituted diamine, leading to preferential removal of the pro-R proton i.e., opposite enantioselectivity to (-)-sparteine. The experimental result with the N-Me-substituted diamine correlated well with the computational results: at the B3P86/6-31G* level, the sense of induction was correctly predicted; the lowest energy complex of isopropyllithium/diamine/N-Boc-pyrrolidine also had the lowest activation energy (DeltaH++ = 11.1 kcal/mol, DeltaG++= 11.5 kcal/mol) for proton transfer. The computational results with the N-(i)Pr-substituted diamine identified a transition state for proton transfer with activation energies of DeltaH++= 11.7 kcal/mol and DeltaG++= 11.8 kcal/mol (at the B3P86/6-31G* level). Although comparable to (-)-sparteine and the N-Me-substituted diamine, these DeltaH++ and DeltaG++ values are at odds with the experimental observation that use of the N-(i)Pr-substituted diamine gave no product. It is suggested that steric crowding inhibits formation of the prelithiation complex rather than increasing the activation enthalpy for proton transfer in the transition state. Three other ligands (N-H and O-substituted as well as a five-membered ring analogue) were studied solely using computational methods, and the results predict that the observed enantioselectivity would be modest at best.
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Affiliation(s)
- Peter O'Brien
- Departments of Chemistry, University of York, Heslington, York YO10 5DD, U.K
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48
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Abstract
Computational methods were used to determine the structure of dilithiodiamines and the effects of solvation by ethereal solvents. Solvation was examined by the use of microsolvation with explicit dimethyl ether or THF ligands and by the combined use of microsolvation and the IEFPCM continuum solvent model. It was determined that each of the compounds studied exists exclusively as a bridged intramolecular dimer, both in the gas phase and in solution. Thermodynamic properties were calculated at 200 and 298 K to estimate the effect of temperature on the cyclization energies. Infrared spectroscopy was used to confirm the proposed intramolecular dimer structures.
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Affiliation(s)
- Lawrence M Pratt
- Department of Chemistry, Fisk University, Nashville, Tennessee 37209, USA.
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49
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Young Lee K, GowriSankar S, Nyoung Kim J. N , N , N ′ , N ′ -Tetramethyl-1,3-propanediamine as the catalyst of choice for the Baylis–Hillman reaction of cycloalkenone: rate acceleration by stabilizing the zwitterionic intermediate via the ion–dipole interaction. Tetrahedron Lett 2004. [DOI: 10.1016/j.tetlet.2004.05.064] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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50
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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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