1
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Evans R. The interpretation of small molecule diffusion coefficients: Quantitative use of diffusion-ordered NMR spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 117:33-69. [PMID: 32471534 DOI: 10.1016/j.pnmrs.2019.11.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 11/20/2019] [Accepted: 11/20/2019] [Indexed: 06/11/2023]
Abstract
Measuring accurate molecular self-diffusion coefficients, D, by nuclear magnetic resonance (NMR) techniques has become routine as hardware, software and experimental methodologies have all improved. However, the quantitative interpretation of such data remains difficult, particularly for small molecules. This review article first provides a description of, and explanation for, the failure of the Stokes-Einstein equation to accurately predict small molecule diffusion coefficients, before moving on to three broadly complementary methods for their quantitative interpretation. Two are based on power laws, but differ in the nature of the reference molecules used. The third addresses the uncertainties in the Stokes-Einstein equation directly. For all three methods, a wide range of examples are used to show the range of chemistry to which diffusion NMR can be applied, and how best to implement the different methods to obtain quantitative information from the chemical systems studied.
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Affiliation(s)
- Robert Evans
- Aston Institute of Materials Research, School of Engineering and Applied Science, Aston University, Birmingham B4 7ET, United Kingdom.
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2
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Abstract
The solution structures, stabilities, physical properties, and reactivities of sodium diisopropylamide (NaDA) in a variety of coordinating solvents are described. NaDA is stable for months as a solid or as a 1.0 M solution in N,N-dimethylethylamine (DMEA) at -20 °C. A combination of NMR spectroscopic and computational studies show that NaDA is a disolvated symmetric dimer in DMEA, N,N-dimethyl-n-butylamine, and N-methylpyrrolidine. Tetrahydrofuran (THF) readily displaces DMEA, affording a tetrasolvated cyclic dimer at all THF concentrations. Dimethoxyethane (DME) and N,N,N',N'-tetramethylethylenediamine quantitatively displace DMEA, affording doubly chelated symmetric dimers. The trifunctional ligands N,N,N',N″,N″-pentamethyldiethylenetriamine and diglyme bind the dimer as bidentate rather than tridentate ligands. Relative rates of solvent decompositions are reported, and rate studies for the decomposition of THF and DME are consistent with monomer-based mechanisms.
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Affiliation(s)
- Russell F. Algera
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301, United States,
| | - Yun Ma
- 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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3
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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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4
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Yu K, Lu P, Jackson JJ, Nguyen TAD, Alvarado J, Stivala CE, Ma Y, Mack KA, Hayton TW, Collum DB, Zakarian A. Lithium Enolates in the Enantioselective Construction of Tetrasubstituted Carbon Centers with Chiral Lithium Amides as Noncovalent Stereodirecting Auxiliaries. J Am Chem Soc 2017; 139:527-533. [PMID: 27997174 PMCID: PMC6097510 DOI: 10.1021/jacs.6b11673] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lithium enolates derived from carboxylic acids are ubiquitous intermediates in organic synthesis. Asymmetric transformations with these intermediates, a central goal of organic synthesis, are typically carried out with covalently attached chiral auxiliaries. An alternative approach is to utilize chiral reagents that form discrete, well-defined aggregates with lithium enolates, providing a chiral environment conducive of asymmetric bond formation. These reagents effectively act as noncovalent, or traceless, chiral auxiliaries. Lithium amides are an obvious choice for such reagents as they are known to form mixed aggregates with lithium enolates. We demonstrate here that mixed aggregates can effect highly enantioselective transformations of lithium enolates in several classes of reactions, most notably in transformations forming tetrasubstituted and quaternary carbon centers. Easy recovery of the chiral reagent by aqueous extraction is another practical advantage of this one-step protocol. Crystallographic, spectroscopic, and computational studies of the central reactive aggregate, which provide insight into the origins of selectivity, are also reported.
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Affiliation(s)
- Kai Yu
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
| | - Ping Lu
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
| | - Jeffrey J Jackson
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
| | - Thuy-Ai D Nguyen
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
| | - Joseph Alvarado
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
| | - Craig E Stivala
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
| | - Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
| | - Kyle A Mack
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
| | - Trevor W Hayton
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
| | - David B Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
| | - Armen Zakarian
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
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5
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Harrison-Marchand A, Barozzino-Consiglio G, Maddaluno J. Chiral Lithium Amides: Tuning Asymmetric Synthesis on the Basis of Structural Parameters. CHEM REC 2016; 17:622-639. [PMID: 27996185 DOI: 10.1002/tcr.201600115] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Indexed: 11/06/2022]
Abstract
An overview on the structural arrangements adopted by Chiral Lithium Amides (CLAs), alone or in mixed complexes, is presented. These species are important reagents for asymmetric synthesis and understanding their organization is essential to improve their design and the reaction conditions.
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Affiliation(s)
- Anne Harrison-Marchand
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA, UMR 6014 & FR 3038), 76000, Rouen, France
| | | | - Jacques Maddaluno
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA, UMR 6014 & FR 3038), 76000, Rouen, France
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6
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Yang Y, Wu R, Huang S, Bai Z. Silica sol assisted chromatographic NMR spectroscopy for resolution of trans- and cis-isomers. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 265:210-214. [PMID: 26942864 DOI: 10.1016/j.jmr.2016.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 02/19/2016] [Accepted: 02/21/2016] [Indexed: 06/05/2023]
Abstract
Chromatographic NMR spectroscopy can separate the mixtures of species with significantly different molecular size, but generally fails for isomeric species. Herein, we reported the resolution of trans- and cis-isomers and their structural analogue, which are different in molecular shapes, but similar in mass, were greatly enhanced in the presence of silica sol. The mixtures of maleic acid, fumaric acid and succinic acid, and the mixtures of trans- and cis-1,2-cyclohexanedicarboxylic acids, were distinguished by virtue of their different degrees of interaction with silica sol. Moreover, we found mixed solvents could improve the spectral resolution of DOSY spectra of mixtures.
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Affiliation(s)
- Ying Yang
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, 266101 Qingdao, China
| | - Rui Wu
- School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, 693 Xiongchu Avenue, 430073 Wuhan, China
| | - Shaohua Huang
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, 266101 Qingdao, China.
| | - Zhengwu Bai
- School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, 693 Xiongchu Avenue, 430073 Wuhan, China
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7
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Orr SA, Kennedy AR, Liggat JJ, McLellan R, Mulvey RE, Robertson SD. Accessible heavier s-block dihydropyridines: structural elucidation and reactivity of isolable molecular hydride sources. Dalton Trans 2016; 45:6234-40. [DOI: 10.1039/c5dt04224k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Transmetallation of lithiodihydropyridines with Group 1 alkoxides provides facile access to reactive MH (M = Na, K) sources, which show significant structural diversity due in part to the distinct ways that Na/K engage with the σ (green) and π (red) donor systems of the DHP ligands.
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Affiliation(s)
- Samantha A. Orr
- WestCHEM
- Department of Pure and Applied Chemistry
- University of Strathclyde
- Glasgow
- UK
| | - Alan R. Kennedy
- WestCHEM
- Department of Pure and Applied Chemistry
- University of Strathclyde
- Glasgow
- UK
| | - John J. Liggat
- WestCHEM
- Department of Pure and Applied Chemistry
- University of Strathclyde
- Glasgow
- UK
| | - Ross McLellan
- WestCHEM
- Department of Pure and Applied Chemistry
- University of Strathclyde
- Glasgow
- UK
| | - Robert E. Mulvey
- WestCHEM
- Department of Pure and Applied Chemistry
- University of Strathclyde
- Glasgow
- UK
| | - Stuart D. Robertson
- WestCHEM
- Department of Pure and Applied Chemistry
- University of Strathclyde
- Glasgow
- UK
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8
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Zhang Y, Wei J, Zhang WX, Xi Z. Lithium Aluminate Complexes and Alumoles from 1,4-Dilithio-1,3-Butadienes and AlEt2Cl. Inorg Chem 2015; 54:10695-700. [DOI: 10.1021/acs.inorgchem.5b01551] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yongliang Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory
of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry, Peking University, Beijing 100871, China
| | - Junnian Wei
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory
of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry, Peking University, Beijing 100871, China
| | - Wen-Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory
of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry, Peking University, Beijing 100871, China
| | - Zhenfeng Xi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory
of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry, Peking University, Beijing 100871, China
- State Key Laboratory of Organometallic
Chemistry, Shanghai Institute of Organic Chemistry (SIOC), Chinese Academy of Sciences, Shanghai 200032, China
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9
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Guang J, Hopson R, Williard PG. Diffusion Coefficient-Formula Weight (D-FW) Analysis of 2H Diffusion-Ordered NMR Spectroscopy (DOSY). J Org Chem 2015; 80:9102-7. [DOI: 10.1021/acs.joc.5b01457] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jie Guang
- 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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10
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Armstrong DR, Harris CMM, Kennedy AR, Liggat JJ, McLellan R, Mulvey RE, Urquhart MDT, Robertson SD. Developing Lithium Chemistry of 1,2-Dihydropyridines: From Kinetic Intermediates to Isolable Characterized Compounds. Chemistry 2015; 21:14410-20. [DOI: 10.1002/chem.201501880] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Indexed: 11/06/2022]
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11
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Lesage D, Barozzino-Consiglio G, Duwald R, Fressigné C, Harrison-Marchand A, Faull KF, Maddaluno J, Gimbert Y. A Lithium Amide Protected Against Protonation in the Gas Phase: Unexpected Effect of LiCl. J Org Chem 2015; 80:6441-6. [DOI: 10.1021/acs.joc.5b00875] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Denis Lesage
- Sorbonne
Universités, UPMC UNIV Paris 06, Institut Parisien de Chimie Moléculaire, UMR CNRS 8232, Case 45, 4 Place Jussieu, 75252 Paris Cedex 05, France
| | | | - Romain Duwald
- Normandie
Université (COBRA), UMR CNRS-Université de Rouen-INSA de Rouen 6014, 76821 Mont St Aignan Cedex, France
| | - Catherine Fressigné
- Normandie
Université (COBRA), UMR CNRS-Université de Rouen-INSA de Rouen 6014, 76821 Mont St Aignan Cedex, France
| | - Anne Harrison-Marchand
- Normandie
Université (COBRA), UMR CNRS-Université de Rouen-INSA de Rouen 6014, 76821 Mont St Aignan Cedex, France
| | - Kym F. Faull
- Pasarow
Mass Spectrometry Laboratory, Semel Institute for Neuroscience and
Human Behavior and Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, California, 90019 United States
| | - Jacques Maddaluno
- Normandie
Université (COBRA), UMR CNRS-Université de Rouen-INSA de Rouen 6014, 76821 Mont St Aignan Cedex, France
| | - Yves Gimbert
- Université
Grenoble Alpes (DCM), UMR CNRS-UJF 5250 BP 53, 38041 Grenoble Cedex 9, France
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12
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Neufeld R, Stalke D. Accurate molecular weight determination of small molecules via DOSY-NMR by using external calibration curves with normalized diffusion coefficients. Chem Sci 2015; 6:3354-3364. [PMID: 29142693 PMCID: PMC5656982 DOI: 10.1039/c5sc00670h] [Citation(s) in RCA: 154] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 03/18/2015] [Indexed: 01/12/2023] Open
Abstract
Determination of the aggregation and solvation numbers of organometallic complexes in solution is an important task to increase insight in reaction mechanisms. Thus knowing which aggregates are formed during a reaction is of high interest to develop better selectivity and higher yields. Diffusion-ordered spectroscopy (DOSY), which separates NMR signals according to the diffusion coefficient, finds increasing use to identify species in solution. However, there still is no simple relationship between diffusion coefficient and molecular weight (MW). Some methods have been developed to estimate the MW but still with a significant error of ±30%. Here we describe a novel development of MW-determination by using an external calibration curve (ECC) approach with normalized diffusion coefficients. Taking the shape of the molecules into account enables accurate MW-predictions with a maximum error of smaller than ±9%. Moreover we show that the addition of multiple internal references is dispensable. One internal reference (that also can be the solvent) is sufficient. If the solvent signal is not accessible, 16 other internal standards (aliphatics and aromatics) are available to avoid signal overlapping problems and provide flexible choice of analytes. This method is independent of NMR-device properties and diversities in temperature or viscosity and offers an easy and robust method to determine accurate MWs in solution.
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Affiliation(s)
- Roman Neufeld
- Institut für Anorganische Chemie , Georg-August-Universität , Tammannstrasse 4 , Göttingen , Germany .
| | - Dietmar Stalke
- Institut für Anorganische Chemie , Georg-August-Universität , Tammannstrasse 4 , Göttingen , Germany .
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13
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Neufeld R, John M, Stalke D. The Donor-Base-Free Aggregation of Lithium Diisopropyl Amide in Hydrocarbons Revealed by a DOSY Method. Angew Chem Int Ed Engl 2015; 54:6994-8. [PMID: 26014367 DOI: 10.1002/anie.201502576] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Indexed: 11/08/2022]
Abstract
Lithium diisopropyl amide (LDA) is a very prominent reagent that plays a key role in organic synthesis, serving as a base par excellence for a broad range of deprotonation reactions. However, the state of aggregation in solution in the absence of donor bases was unclear. In this paper we solved this problem by employing DOSY NMR experiments based on a newly elaborated external calibration curve (ECC) approach with normalized diffusion coefficients.
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Affiliation(s)
- Roman Neufeld
- Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, 37077 Göttingen (Germany)
| | - Michael John
- Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, 37077 Göttingen (Germany)
| | - Dietmar Stalke
- Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, 37077 Göttingen (Germany).
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14
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Neufeld R, John M, Stalke D. Aufklärung der donorbasenfreien Aggregation von Lithiumdiisopropylamid in Kohlenwasserstoffen mithilfe einer DOSY-Methode. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201502576] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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16
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Lu P, Jackson JJ, Eickhoff JA, Zakarian A. Direct enantioselective conjugate addition of carboxylic acids with chiral lithium amides as traceless auxiliaries. J Am Chem Soc 2015; 137:656-9. [PMID: 25562717 PMCID: PMC4308744 DOI: 10.1021/ja512213c] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Michael addition is a premier synthetic method for carbon-carbon and carbon-heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B.
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Affiliation(s)
- Ping Lu
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
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