1
|
Fu X, Zhao Q, Zhao W. Synthesis of β‐Alkoxy Amines from Alkenes, Sulfonyl Azides, and Alcohols though Copper‐Catalyzed Three‐Component Tandem Reactions via Regioselective Ring‐Opening of Aziridine Intermediates. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Xiao‐Fei Fu
- College of Chemistry and Chemical Engineering Shangqiu Normal University Shangqiu 476000 P. R. China
- College of Chemistry Zhengzhou University Zhengzhou 450001 P. R. China
| | - Qiang Zhao
- Department of Chemistry Purdue University West Lafayette Indiana 47907 United States
| | - Wen‐Xian Zhao
- College of Chemistry and Chemical Engineering Shangqiu Normal University Shangqiu 476000 P. R. China
- College of Chemistry Zhengzhou University Zhengzhou 450001 P. R. China
| |
Collapse
|
2
|
Nikitin K, O'Gara R. Mechanisms and Beyond: Elucidation of Fluxional Dynamics by Exchange NMR Spectroscopy. Chemistry 2019; 25:4551-4589. [PMID: 30421834 DOI: 10.1002/chem.201804123] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Indexed: 12/31/2022]
Abstract
Detailed mechanistic information is crucial to our understanding of reaction pathways and selectivity. Dynamic exchange NMR techniques, in particular 2D exchange spectroscopy (EXSY) and its modifications, provide indispensable intricate information on the mechanisms of organic and inorganic reactions and other phenomena, for example, the dynamics of interfacial processes. In this Review, key results from exchange NMR studies of small molecules over the last few decades are systemised and discussed. After a brief introduction to the theory, the key types of dynamic processes are identified and fundamental examples given of intra- and intermolecular reactions, which, in turn, could involve, or not, bond-making and bond-breaking events. Following that logic, internal molecular rotation, intramolecular stereomutation and molecular recognition will first be considered because they do not typically involve bond breaking. Then, rearrangements, substitution-type reactions, cyclisations, additions and other processes affecting chemical bonds will be discussed. Finally, interfacial molecular dynamics and unexpected combinations of different types of fluxional processes will also be highlighted. How exchange NMR spectroscopy helps to identify conformational changes, coordination and molecular recognition processes as well as quantify reaction energy barriers and extract detailed mechanistic information by using reaction rate theory in conjunction with computational techniques will be shown.
Collapse
Affiliation(s)
- Kirill Nikitin
- School of Chemistry, University College Dublin, Belfield, Dublin, Ireland
| | - Ryan O'Gara
- School of Chemistry, University College Dublin, Belfield, Dublin, Ireland
| |
Collapse
|
3
|
Knorr R, Schmidt B, Mehlstäubl J, von Roman T. Structures and stereoinversions of β-shielded α-Li (or K or Cs)-acrylonitriles: A mechanism with neighborly assistance. J Organomet Chem 2018. [DOI: 10.1016/j.jorganchem.2018.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Mas-Roselló J, Hachisu S, Clayden J. Geometry-Retentive C-Alkenylation of Lithiated α-Aminonitriles: Quaternary α-Alkenyl Amino Acids and Hydantoins. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201704908] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Josep Mas-Roselló
- School of Chemistry; University of Bristol; Cantock's Close Bristol BS8 1TS UK
| | - Shuji Hachisu
- Syngenta Agrochemicals; Jealotts Hill Research Station Bracknell, Berks RG42 6EY UK
| | - Jonathan Clayden
- School of Chemistry; University of Bristol; Cantock's Close Bristol BS8 1TS UK
| |
Collapse
|
7
|
Mas-Roselló J, Hachisu S, Clayden J. Geometry-Retentive C-Alkenylation of Lithiated α-Aminonitriles: Quaternary α-Alkenyl Amino Acids and Hydantoins. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/anie.201704908] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Josep Mas-Roselló
- School of Chemistry; University of Bristol; Cantock's Close Bristol BS8 1TS UK
| | - Shuji Hachisu
- Syngenta Agrochemicals; Jealotts Hill Research Station Bracknell, Berks RG42 6EY UK
| | - Jonathan Clayden
- School of Chemistry; University of Bristol; Cantock's Close Bristol BS8 1TS UK
| |
Collapse
|
8
|
|
9
|
Sadhukhan A, Hobbs MC, Meijer AJHM, Coldham I. Highly enantioselective metallation-substitution alpha to a chiral nitrile. Chem Sci 2017; 8:1436-1441. [PMID: 28616143 PMCID: PMC5460602 DOI: 10.1039/c6sc03712g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 10/24/2016] [Indexed: 11/21/2022] Open
Abstract
Nitrile anions do not necessarily lack stereochemical integrity and we show good results for stereospecific reaction with a simple magnesium base.
We report the deprotonation of a chiral nitrile and reaction of the resulting chiral organometallic species with a variety of electrophiles to give highly enantiomerically enriched 2-substituted nitrile products. The nitrile was treated with TMPMgCl and the resulting anion, an asymmetric alpha cyano Grignard species, was found to be configurationally stable at low temperature for a short time (half-life several minutes at –104 °C).
Collapse
Affiliation(s)
- Arghya Sadhukhan
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield , S3 7HF , UK .
| | - Melanie C Hobbs
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield , S3 7HF , UK .
| | - Anthony J H M Meijer
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield , S3 7HF , UK .
| | - Iain Coldham
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield , S3 7HF , UK .
| |
Collapse
|
10
|
Hamdoun G, Gouilleux B, Sebban M, Barozzino-Consiglio G, Harrison-Marchand A, Giraudeau P, Maddaluno J, Oulyadi H. 2D 7Li Ultrafast CT-COSY: a new tool for the rapid measurement of tiny homonuclear lithium scalar couplings. Chem Commun (Camb) 2017; 53:220-223. [DOI: 10.1039/c6cc08744b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report on the first examples of 7Li Ultrafast (UF) CT-COSY spectra from lithiated samples and on the usefulness of these experiments for the quantitative estimation of the 2J7Li–7Li in a much shorter time.
Collapse
Affiliation(s)
- G. Hamdoun
- Normandie Univ
- UNIROUEN
- INSA Rouen
- CNRS
- COBRA (UMR 6014 & FR 3038)
| | - B. Gouilleux
- CEISAM
- Université de Nantes
- UMR CNRS 6230
- 44322 Nantes
- France
| | - M. Sebban
- Normandie Univ
- UNIROUEN
- INSA Rouen
- CNRS
- COBRA (UMR 6014 & FR 3038)
| | | | | | - P. Giraudeau
- CEISAM
- Université de Nantes
- UMR CNRS 6230
- 44322 Nantes
- France
| | - J. Maddaluno
- Normandie Univ
- UNIROUEN
- INSA Rouen
- CNRS
- COBRA (UMR 6014 & FR 3038)
| | - H. Oulyadi
- Normandie Univ
- UNIROUEN
- INSA Rouen
- CNRS
- COBRA (UMR 6014 & FR 3038)
| |
Collapse
|
11
|
Lin S, Kumagai N, Shibasaki M. Enantioselective synthesis of α,α-disubstituted α-amino acids via direct catalytic asymmetric addition of acetonitrile to α-iminoesters. Org Biomol Chem 2016; 14:9725-9730. [DOI: 10.1039/c6ob01874b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chiral N-heterocyclic carbene complexes of [Ir(cod)(OMe)]2 in combination with Barton's base enabled direct enantioselective addition of acetonitrile to α-iminoesters.
Collapse
Affiliation(s)
- Shaoquan Lin
- Institute of Microbial Chemistry (BIKAKEN)
- Tokyo
- Tokyo 141-0021
- Japan
| | - Naoya Kumagai
- Institute of Microbial Chemistry (BIKAKEN)
- Tokyo
- Tokyo 141-0021
- Japan
| | | |
Collapse
|
12
|
Lu P, Pakkala VS, Evanseck JD, Fleming FF. Metalated nitriles: S Ni' cyclizations with a propargylic electrophile. Tetrahedron Lett 2015; 56:3216-3219. [PMID: 26120212 PMCID: PMC4480775 DOI: 10.1016/j.tetlet.2015.01.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
A rare 5-exo-dig SNi' cyclization with magnesiated and lithiated nitriles affords a cis-fused hydrindane bearing an exocyclic allene. The cyclization of the dilithiated nitrile pits a stereoelectronic preference for a trans-hydrindane against a cyclization through a less strained transition structure to the corresponding cis-hydrindane. Computational modeling suggests that the dilithiated nitrile cyclizes to a cis-hydrindane because the preferred transition structure positions the lithium cation in a cone of electron density that bridges the nitrile-bearing carbon, an alkoxide, and an electron-rich alkyne functionality.
Collapse
Affiliation(s)
- Ping Lu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282-1530, USA
| | - Venkata S. Pakkala
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282-1530, USA
| | - Jeffrey D. Evanseck
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282-1530, USA
| | - Fraser F. Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282-1530, USA
| |
Collapse
|
13
|
Hamdoun G, Sebban M, Tognetti V, Harrison-Marchand A, Joubert L, Maddaluno J, Oulyadi H. Alkyllithium Mixed Aggregates: Dynamic Behavior and Comprehensive Analysis of NMR 2J7Li–7Li Spin–Spin Coupling. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00162] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ghanem Hamdoun
- Normandie Université, COBRA, UMR6014 & FR3038 CNRS, Université de Rouen, INSA de Rouen, 76821 Mont-Saint-Aignan Cedex, France
| | - Muriel Sebban
- Normandie Université, COBRA, UMR6014 & FR3038 CNRS, Université de Rouen, INSA de Rouen, 76821 Mont-Saint-Aignan Cedex, France
| | - Vincent Tognetti
- Normandie Université, COBRA, UMR6014 & FR3038 CNRS, Université de Rouen, INSA de Rouen, 76821 Mont-Saint-Aignan Cedex, France
| | - Anne Harrison-Marchand
- Normandie Université, COBRA, UMR6014 & FR3038 CNRS, Université de Rouen, INSA de Rouen, 76821 Mont-Saint-Aignan Cedex, France
| | - Laurent Joubert
- Normandie Université, COBRA, UMR6014 & FR3038 CNRS, Université de Rouen, INSA de Rouen, 76821 Mont-Saint-Aignan Cedex, France
| | - Jacques Maddaluno
- Normandie Université, COBRA, UMR6014 & FR3038 CNRS, Université de Rouen, INSA de Rouen, 76821 Mont-Saint-Aignan Cedex, France
| | - Hassan Oulyadi
- Normandie Université, COBRA, UMR6014 & FR3038 CNRS, Université de Rouen, INSA de Rouen, 76821 Mont-Saint-Aignan Cedex, France
| |
Collapse
|
14
|
Plessel KN, Jones AC, Wherritt DJ, Maksymowicz RM, Poweleit E, Reich HJ. A Rapid Injection NMR Study of the Reaction of Organolithium Reagents with Esters, Amides, and Ketones. Org Lett 2015; 17:2310-3. [DOI: 10.1021/acs.orglett.5b00650] [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)
- Kristin N. Plessel
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Amanda C. Jones
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Daniel J. Wherritt
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Rebecca M. Maksymowicz
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - EricT. Poweleit
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Hans J. Reich
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| |
Collapse
|
15
|
Sureshkumar D, Ganesh V, Kumagai N, Shibasaki M. Direct Catalytic Addition of Alkylnitriles to Aldehydes by Transition-Metal/NHC Complexes. Chemistry 2014; 20:15723-6. [DOI: 10.1002/chem.201404808] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Indexed: 11/06/2022]
|
16
|
Su C, Hopson R, Williard PG. Influence of Steric Factors on Chiral Lithium Amide Aggregates. J Am Chem Soc 2014; 136:3246-55. [DOI: 10.1021/ja4123957] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chicheung Su
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912 United States
| | - Russell Hopson
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912 United States
| | - Paul G. Williard
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912 United States
| |
Collapse
|
17
|
Su C, Hopson R, Williard PG. Mixed aggregates of an alkyl lithium reagent and a chiral lithium amide derived from N-ethyl-O-triisopropylsilyl valinol. J Am Chem Soc 2013; 135:14367-79. [PMID: 23980610 DOI: 10.1021/ja406912h] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The crystal structure of a mixed aggregate containing lithiated (S)-N-ethyl-3-methyl-1-(triisopropylsilyloxy)butan-2-amine derived from (S)-valinol and cyclopentyllithium is determined by X-ray diffraction. The mixed aggregate adopts a ladder structure in the solid state. The ladder-type mixed aggregate is also the major species in a toluene-d8 solution containing an approximately 1:1 molar ratio of the lithiated chiral amide to cyclopentyllithium. A variety of NMR experiments including diffusion-ordered NMR spectroscopy (DOSY) with diffusion coefficient-formula (D-FW) weight correlation analyses and other one- and two-dimensional NMR techniques allowed us to characterize the complex in solution. Solution state structures of the mixed aggregates of n-butyl, sec-butyllithium, isopropyllithium with lithiated (S)-N-ethyl-3-methyl-1-(triisopropylsilyloxy)butan-2-amine are also reported. Identical dimeric, ladder-type, mixed aggregates are the major species at a stoichiometric ratio of 1:1 lithium chiral amide to alkyllithium in toluene-d8 solution for all of the different alkyllithium reagents.
Collapse
Affiliation(s)
- Chicheung Su
- Department of Chemistry, Brown University , 324 Brook Street,Providence, Rhode Island 02912, United States
| | | | | |
Collapse
|
18
|
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
| |
Collapse
|
19
|
Su C, Hopson R, Williard PG. Crystal structure and solution state characterization of lithium (S)-(1-(bis(2-methoxyethyl)amino)-3-methylbutan-2-yl)(methyl)amide. J Org Chem 2013; 78:7288-92. [PMID: 23767993 DOI: 10.1021/jo400839q] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The solid state structure of lithiated (S)-N(1),N(1)-bis(2-methoxyethyl)-N(2),3-dimethylbutane-1,2-diamine, which is a chiral amide base synthesized from (S)-valine was determined by single-crystal X-ray diffraction. The complex in solution state is also characterized by a variety of NMR experiments including diffusion-ordered NMR spectroscopy (DOSY) with diffusion coefficient-formula weight correlation analyses and other one- and two-dimensional NMR techniques by dissolving the crystal in toluene-d8. The crystallography and NMR results suggest that the chiral amide is dimeric in both solid and solution states.
Collapse
Affiliation(s)
- Chicheung Su
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | | | | |
Collapse
|
20
|
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]
|
21
|
Barker G, Alshawish MR, Skilbeck MC, Coldham I. Remarkable Configurational Stability of Magnesiated Nitriles. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201303442] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
22
|
Barker G, Alshawish MR, Skilbeck MC, Coldham I. Remarkable Configurational Stability of Magnesiated Nitriles. Angew Chem Int Ed Engl 2013; 52:7700-3. [DOI: 10.1002/anie.201303442] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Indexed: 11/08/2022]
|
23
|
Chakraborty S, Patel YJ, Krause JA, Guan H. A Robust Nickel Catalyst for Cyanomethylation of Aldehydes: Activation of Acetonitrile under Base-Free Conditions. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201302613] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
24
|
Chakraborty S, Patel YJ, Krause JA, Guan H. A Robust Nickel Catalyst for Cyanomethylation of Aldehydes: Activation of Acetonitrile under Base-Free Conditions. Angew Chem Int Ed Engl 2013; 52:7523-6. [DOI: 10.1002/anie.201302613] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Indexed: 11/08/2022]
|
25
|
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]
|
26
|
Affiliation(s)
- Hans J. Reich
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| |
Collapse
|
27
|
Kagan G, Li W, Li D, Hopson R, Williard PG. Characterization of dimeric chiral lithium amide structures derived from N-isopropyl-O- triisopropylsilyl valinol. J Am Chem Soc 2011; 133:6596-602. [PMID: 21486016 DOI: 10.1021/ja109041z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dimeric structure is characterized for a chiral amide base complex consisting of an (S)-N-isopropyl-O-triisopropylsilyl valinol ligand and lithium. The complex is characterized by a variety of NMR techniques, including multinuclear one- and two-dimensional NMR experiments and diffusion-ordered NMR spectroscopy (DOSY) as well as diffusion coefficient-formula weight (D-fw) correlation analyses. Spartan calculations are presented which support the structural assignment. This structural characterization leads to an explanation of the behavior and the reactivity of these complexes in solution.
Collapse
Affiliation(s)
- Gerald Kagan
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912, USA
| | | | | | | | | |
Collapse
|
28
|
Kolonko KJ, Biddle MM, Guzei IA, Reich HJ. Solution Structures of Lithium Enolates of Cyclopentanone, Cyclohexanone, Acetophenones, and Benzyl Ketones. Triple Ions and Higher Lithiate Complexes. J Am Chem Soc 2009; 131:11525-34. [DOI: 10.1021/ja903479p] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Margaret M. Biddle
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Ilia A. Guzei
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Hans J. Reich
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| |
Collapse
|
29
|
Andrews PC, Koutsaplis M, Robertson EG. Thermodynamically Favored Anion Rearrangements in Li and Na Complexes of (S)-N-α-(Methylbenzyl)allylamine. Organometallics 2009. [DOI: 10.1021/om801165e] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Philip C. Andrews
- School of Chemistry, Monash University, P.O. Box 23, Melbourne, Victoria 3800, Australia
| | - Magdaline Koutsaplis
- School of Chemistry, Monash University, P.O. Box 23, Melbourne, Victoria 3800, Australia
| | - Evan G. Robertson
- School of Chemistry, Monash University, P.O. Box 23, Melbourne, Victoria 3800, Australia
| |
Collapse
|
30
|
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.
Collapse
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
| |
Collapse
|
31
|
Gschwind RM. Organocuprates and Diamagnetic Copper Complexes: Structures and NMR Spectroscopic Structure Elucidation in Solution. Chem Rev 2008; 108:3029-53. [DOI: 10.1021/cr800286r] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ruth M. Gschwind
- Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, D-93040 Regensburg, Germany
| |
Collapse
|
32
|
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.
Collapse
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,
| |
Collapse
|
33
|
Liu J, Li D, Sun C, Williard PG. Analysis of an asymmetric addition with a 2:1 mixed lithium amide/n-butyllithium aggregate. J Org Chem 2008; 73:4045-52. [PMID: 18459811 DOI: 10.1021/jo800592d] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A 2:1 lithium amide/ n-butyllithium aggregate 1 is investigated as an asymmetric addition template in hydrocarbon solvents. Several different chiral lithium amides were synthesized from l-valine and tested in the asymmetric addition of n-BuLi to various aldehydes. Enantiomeric excesses up to 83% were obtained in the case of the addition of n-BuLi to pivaldehyde at -116 degrees C in pentane. (1)H and (13)C INEPT DOSY were utilized to characterize a new trimeric complex 12 between 2 equiv of lithium amide and 1 equiv of lithium alkoxide. This mixed aggregate strongly indicates the possibility of product-induced chirality inhibition that is detrimental to the enantioselectivity of asymmetric addition reaction.
Collapse
Affiliation(s)
- Jia Liu
- Department of Chemistry, Brown University, Providence, RI 02912, USA
| | | | | | | |
Collapse
|
34
|
Li D, Sun C, Liu J, Hopson R, Li W, Williard PG. Aggregation studies of complexes containing a chiral lithium amide and n-Butyllithium. J Org Chem 2008; 73:2373-81. [PMID: 18294002 DOI: 10.1021/jo702655m] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A system consisting of a chiral lithium amide and n-BuLi in tol-d(8) solution was investigated with (1)H and (13)C INEPT DOSY, (6)Li and (15)N NMR, and other 2D NMR techniques. A mixed 2:1 trimeric complex was identified as the major species as the stoichiometry approached 1.5 equiv of n-BuLi to 1 equiv of amine compound. (1)H and (13)C INEPT DOSY spectra confirmed this lithium aggregate in the solution. The formula weight of the aggregate, correlated with diffusion coefficients of internal references, indicated the aggregation number of this complex. Plots of log D(rel) vs log FW are linear (r > 0.9900). (6)Li and (15)N NMR titration experiments also corroborated these results. These NMR experiments indicate that this mixed aggregate is the species that is responsible for asymmetric addition of n-BuLi to aldehydes.
Collapse
Affiliation(s)
- Deyu Li
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | | | | | | | | | | |
Collapse
|
35
|
Fleming F, Liu W, Ghosh S, Steward O. Metalated Nitriles: Internal 1,2-Asymmetric Induction. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200701550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
36
|
Fleming FF, Liu W, Ghosh S, Steward OW. Metalated Nitriles: Internal 1,2-Asymmetric Induction. Angew Chem Int Ed Engl 2007; 46:7098-100. [PMID: 17691084 DOI: 10.1002/anie.200701550] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Fraser F Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282-1530, USA.
| | | | | | | |
Collapse
|
37
|
Ghorai MK, Das K, Shukla D. Lewis acid-mediated highly regioselective SN2-Type ring-opening of 2-aryl-N-tosylazetidines and aziridines by alcohols. J Org Chem 2007; 72:5859-62. [PMID: 17592875 DOI: 10.1021/jo0703294] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lewis acid-mediated highly regioselective SN2-type ring-opening of 2-aryl-N-tosylazetidines with alcohols to afford various 1,3-amino ethers in excellent yields with good enantiomeric excess is described. Similar SN2-type ring-opening of chiral 2-phenyl-N-tosylaziridine with various alcohols produces the corresponding nonracemic 1,2-amino ethers in excellent yields and good ee. The mechanism of the ring-opening of aziridines and azetidines via an SN2 pathway is supported by the formation of nonracemic amino ethers.
Collapse
Affiliation(s)
- Manas K Ghorai
- Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India.
| | | | | |
Collapse
|
38
|
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
| |
Collapse
|
39
|
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.
Collapse
Affiliation(s)
- Fraser F Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282-1530, USA.
| | | | | | | | | |
Collapse
|
40
|
|
41
|
Granander J, Sott R, Hilmersson G. Correlation between the6Li,15N Coupling Constant and the Coordination Number at Lithium. Chemistry 2006; 12:4191-7. [PMID: 16526078 DOI: 10.1002/chem.200501371] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The 6Li,15N coupling constants of lithium amide dimers and their mixed complexes with n-butyllithium, formed from five different chiral amines derived from (S)-[15N]phenylalanine, were determined in diethyl ether (Et2O), tetrahydrofuran (THF) and toluene. Results of NMR spectroscopy studies of these complexes show a clear difference in 6Li,15N coupling constants between di-, tri- and tetracoordinated lithium atoms. The lithium amide dimers with a chelating ether group exhibit 6Li,15N coupling constants of approximately 3.8 and approximately 5.5 Hz for the tetracoordinated and tricoordinated lithium atoms, respectively. The lithium amide dimers with a chelating thioether group show distinctly larger 6Li,15N coupling constants of approximately 4.4 Hz for the tetracoordinated lithium atoms, and the tricoordinated lithium atoms have smaller 6Li,15N coupling constants, approximately 4.9 Hz, than their ether analogues. In diethyl ether and tetrahydrofuran, mixed dimeric complexes between the lithium amides and n-butyllithium are formed. The tetracoordinated lithium atoms of these complexes have 6Li,15N coupling constants of approximately 4.0 Hz, and the 6Li,15N coupling constants of the tricoordinated lithium atoms differ somewhat, depending on whether the chelating group is an ether or a thioether; approximately 5.1 and approximately 4.6 Hz, respectively. In toluene, mixed trimeric complexes are formed from two lithium amide moieties and one n-butyllithium. In these trimers, two lithium atoms are tricoordinated with 6Li,15N coupling constants of approximately 4.6 Hz and one lithium is dicoordinated with 6Li,15N coupling constants of approximately 6.5 Hz.
Collapse
Affiliation(s)
- Johan Granander
- Department of Chemistry, Göteborg University, 41296 Göteborg, Sweden
| | | | | |
Collapse
|
42
|
Gérard H, de la Lande A, Maddaluno J, Parisel O, Tuckerman ME. Revisiting the Structure of (LiCH3)n Aggregates Using Car−Parrinello Molecular Dynamics. J Phys Chem A 2006; 110:4787-94. [PMID: 16599447 DOI: 10.1021/jp056326h] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The theoretical study of (LiMe)(n) aggregates using Car-Parrinello molecular dynamics was undertaken. With respect to a quantum chemical static treatment, this approach furnishes supplementary information about the structural parameters. Equilibrium structures are indeed stable to ca. 300 K, provided the methyl groups in the aggregates are considered to rotate essentially freely. The Li-C distance depends on the coordination number of Li and not so much on the degree of aggregation. Finally, above 650 K, the cubic LiCH(3) tetramer (which is energetically favored) undergoes an entropy-driven rearrangement to a planar structure.
Collapse
Affiliation(s)
- Hélène Gérard
- Laboratoire de Chimie Théorique, Université Pierre et Marie Curie-- Paris 6, UMR 7616, CC 137, 4 place Jussieu, 75252 Paris Cedex 05, France.
| | | | | | | | | |
Collapse
|
43
|
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.
Collapse
Affiliation(s)
- Fraser F Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530, USA.
| | | | | | | |
Collapse
|
44
|
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.
Collapse
Affiliation(s)
- Fraser F Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530, USA.
| | | | | | | | | |
Collapse
|
45
|
Solvent effects on the mixed aggregates of chiral 3-aminopyrrolidine lithium amides and alkyllithiums. Tetrahedron 2005. [DOI: 10.1016/j.tet.2005.01.095] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
46
|
Fleming FF, Zhang Z, Liu W, Knochel P. Metalated Nitriles: Organolithium, -magnesium, and -copper Exchange of α-Halonitriles. J Org Chem 2005; 70:2200-5. [PMID: 15760206 DOI: 10.1021/jo047877r] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text] alpha-Halonitriles react with alkyllithium, organomagnesium, and lithium dimethylcuprate reagents generating reactive, metalated nitriles. The rapid halogen-metal exchange with alkyllithium and Grignard reagents allows selective exchange in the presence of reactive carbonyl electrophiles, including aldehydes, providing a high-yielding alkylation protocol. Lithiated and magnesiated nitriles react with propargyl bromide by S(N)2 displacement whereas organocopper nitriles react by S(N)2' displacement, correlating with the formation of a C-metalated nitrile.
Collapse
Affiliation(s)
- Fraser F Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530, USA.
| | | | | | | |
Collapse
|