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Izquierdo-Aranda L, Adam R, Cabrero-Antonino JR. Silver Supported Nanoparticles on [Mg 4 Al-LDH] as an Efficient Catalyst for the α-Alkylation of Nitriles, Oxindoles and Other Carboxylic Acid Derivatives with Alcohols. CHEMSUSCHEM 2023:e202300818. [PMID: 37486295 DOI: 10.1002/cssc.202300818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 07/24/2023] [Accepted: 07/24/2023] [Indexed: 07/25/2023]
Abstract
An efficient heterogeneous silver-catalyzed α-alkylation of nitriles and oxindoles using alcohols via borrowing hydrogen strategy has been developed for the first time. The active nanostructured material, namely [Ag/Mg4 Al-LDH], composed by silver nanoparticles (3-4 nm average particle size) homogeneously stabilized onto a [Mg4 Al-LDH] support with suitable Brønsted basic properties, constitutes a stable catalyst for the sustainable building of novel C-C bonds from alcohols and C-nucleophiles. By applying this catalyst, a broad range of α-functionalized nitriles and oxindoles has been accessed with good to excellent isolated yields and without the addition of external bases. Moreover, the novel silver nanocatalyst has also demonstrated its successful application to the cyclization of N-[2-(hydroxymethyl)phenyl]-2-phenylacetamides to afford 3-arylquinolin-2(1H)-ones, through a one-pot dehydrogenation and intramolecular α-alkylation. Control experiments, kinetic studies, and characterization data of a variety of [Ag/LDH]-type materials confirmed the silver role in the dehydrogenation and hydrogenation steps, while [Mg4 Al-LDH] matrix is able to catalyze condensation. Interestingly, these studies suggest as key point for the successful activity of [Ag/Mg4 Al-LDH], in comparison with other [Ag/LDH]-type nanocatalysts, the suitable acid-base properties of this material.
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Affiliation(s)
- Luis Izquierdo-Aranda
- Instituto de Tecnología Química, Universitat Politécnica de València-Consejo Superior Investigaciones Científicas (UPV-CSIC), Avda. de los Naranjos s/n, 46022, València, Spain
| | - Rosa Adam
- Instituto de Tecnología Química, Universitat Politécnica de València-Consejo Superior Investigaciones Científicas (UPV-CSIC), Avda. de los Naranjos s/n, 46022, València, Spain
- Departament de Química Orgànica, Facultat de Farmàcia, Universitat de València, Av. Vicent Andrés Estellés s/n, 46100, Burjassot, València, Spain
| | - Jose R Cabrero-Antonino
- Instituto de Tecnología Química, Universitat Politécnica de València-Consejo Superior Investigaciones Científicas (UPV-CSIC), Avda. de los Naranjos s/n, 46022, València, Spain
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2
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Xiao J, Li F, Zhong T, Wu X, Guo F, Li Q, Tang ZL. Copper-catalyzed radical oxidative C(sp3)–H/C(sp3)–H cross-coupling between arylacetonitriles and benzylic compounds. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Balkenhohl M, Jangra H, Makarov IS, Yang S, Zipse H, Knochel P. A Predictive Model Towards Site-Selective Metalations of Functionalized Heterocycles, Arenes, Olefins, and Alkanes using TMPZnCl⋅LiCl. Angew Chem Int Ed Engl 2020; 59:14992-14999. [PMID: 32400069 PMCID: PMC7497272 DOI: 10.1002/anie.202005372] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Indexed: 01/02/2023]
Abstract
The development of a predictive model towards site-selective deprotometalation reactions using TMPZnCl⋅LiCl is reported (TMP=2,2,6,6-tetramethylpiperidinyl). The pKa values of functionalized N-, S-, and O-heterocycles, arenes, alkenes, or alkanes were calculated and compared to the experimental deprotonation sites. Large overlap (>80 %) between the calculated and empirical deprotonation sites was observed, showing that thermodynamic factors strongly govern the metalation regioselectivity. In the case of olefins, calculated frozen state energies of the deprotonated substrates allowed a more accurate prediction. Additionally, various new N-heterocycles were analyzed and the metalation regioselectivities rationalized using the predictive model.
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Affiliation(s)
- Moritz Balkenhohl
- Department of ChemistryLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MunichGermany
| | - Harish Jangra
- Department of ChemistryLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MunichGermany
| | - Ilya S. Makarov
- Department of ChemistryLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MunichGermany
| | - Shu‐Mei Yang
- Department of ChemistryNational (Taiwan) Normal University88, Sec. 4, Tingchow RoadTaipei11677Taiwan, Republic of China
| | - Hendrik Zipse
- Department of ChemistryLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MunichGermany
| | - Paul Knochel
- Department of ChemistryLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MunichGermany
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4
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Balkenhohl M, Jangra H, Makarov IS, Yang S, Zipse H, Knochel P. A Predictive Model Towards Site‐Selective Metalations of Functionalized Heterocycles, Arenes, Olefins, and Alkanes using TMPZnCl⋅LiCl. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005372] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Moritz Balkenhohl
- Department of Chemistry Ludwig-Maximilians-Universität München Butenandtstr. 5–13 81377 Munich Germany
| | - Harish Jangra
- Department of Chemistry Ludwig-Maximilians-Universität München Butenandtstr. 5–13 81377 Munich Germany
| | - Ilya S. Makarov
- Department of Chemistry Ludwig-Maximilians-Universität München Butenandtstr. 5–13 81377 Munich Germany
| | - Shu‐Mei Yang
- Department of Chemistry National (Taiwan) Normal University 88, Sec. 4, Tingchow Road Taipei 11677 Taiwan, Republic of China
| | - Hendrik Zipse
- Department of Chemistry Ludwig-Maximilians-Universität München Butenandtstr. 5–13 81377 Munich Germany
| | - Paul Knochel
- Department of Chemistry Ludwig-Maximilians-Universität München Butenandtstr. 5–13 81377 Munich Germany
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5
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Pitta BR, Steward OW, Fleming FF. Electrophile-Dependent Alkylations of Lithiated 4-Alkoxyalk-4-enenitriles. J Org Chem 2018; 83:2753-2762. [PMID: 29432696 DOI: 10.1021/acs.joc.7b03205] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alkylations of acyclic, lithiated 4-alkoxyalk-4-enenitriles are highly diastereoselective with an unusual electrophile-dependent preference. Alkyl halides, sulfur, chlorine, and acyl cyanide electrophiles intercept a series of lithiated 4-alkoxyalk-4-enenitriles to install contiguous tertiary-quaternary stereocenters with high diastereoselectivity, whereas acylations with ester and carbonate electrophiles are modestly selective. The diastereoselectivity is consistent with electrophilic attack on the most accessible face of the lithated nitrile for most electrophiles except ester and carbonate electrophiles, which likely precoordinate the lithiated nitrile before acylation. Intercepting the lithiated 4-alkoxyalk-4-enenitriles with a range of electrophiles provide insight into the criteria for otherwise challenging diastereoselective alkylations and acylations of acyclic nitriles.
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Affiliation(s)
| | - Omar W Steward
- Department of Chemistry and Biochemistry, Duquesne University , Pittsburgh, Pennsylvania 15282, United States
| | - Fraser F Fleming
- Department of Chemistry, Drexel University , Philadelphia, Pennsylvania 19104, United States
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6
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Yang X, Fleming FF. C- and N-Metalated Nitriles: The Relationship between Structure and Selectivity. Acc Chem Res 2017; 50:2556-2568. [PMID: 28930437 DOI: 10.1021/acs.accounts.7b00329] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Metalated nitriles are exceptional nucleophiles capable of forging highly hindered stereocenters in cases where enolates are unreactive. The excellent nucleophilicity emanates from the powerful inductive stabilization of adjacent negative charge by the nitrile, which has a miniscule steric demand. Inductive stabilization is the key to understanding the reactivity of metalated nitriles because this permits a continuum of structures that range from N-metalated ketenimines to nitrile anions. Solution and solid-state analyses reveal two different metal coordination sites, the formally anionic carbon and the nitrile nitrogen, with the site of metalation depending intimately on the solvent, counterion, temperature, and ligands. The most commonly encountered structures, C- and N-metalated nitriles, have either sp3 or sp2 hybridization at the nucleophilic carbon, which essentially translates into two distinct organometallic species with similar but nonidentical stereoselectivity, regioselectivity, and reactivity preferences. The hybridization differences are particularly important in SNi displacements of cyclic nitriles because the orbital orientations create very precise trajectories that control the cyclization selectivity. Harnessing the orbital differences between C- and N-metalated nitriles allows selective cyclization to afford nitrile-containing cis- or trans-hydrindanes, decalins, or bicyclo[5.4.0]undecanes. Similar orbital constraints favor preferential SNi displacements with allylic electrophiles on sp3 centers over sp2 centers. The strategy permits stereoselective displacements on secondary centers to set contiguous tertiary and quaternary stereocenters or even contiguous vicinal quaternary centers. Stereoselective alkylations of acyclic nitriles are inherently more challenging because of the difficulty in creating steric differentiation in a dynamic system with rotatable bonds. However, judicious substituent placement of vicinal dimethyl groups and a trisubstituted alkene sufficiently constrains C- and N-metalated nitriles to install quaternary stereocenters with excellent 1,2-induction. The structural differences between C- and N-metalated nitriles permit a rare series of chemoselective alkylations with bifunctional electrophiles. C-Magnesiated nitriles preferentially react with carbonyl electrophiles, whereas N-lithiated nitriles favor SN2 displacement of alkyl halides. The chemoselective alkylations potentially provide a strategy for late-stage alkylations of polyfunctional electrophiles en route to bioactive targets. In this Account, the bonding of metalated nitriles is summarized as a prelude to the different strategies for selectively preparing C- and N-metalated nitriles. With this background, the Account then transitions to applications in which C- or N-metalated nitriles allow complementary diastereoselectivity in alkylations and arylations, and regioselective alkylations and arylations, with acyclic and cyclic nitriles. In the latter sections, a series of regiodivergent cyclizations are described that provide access to cis- and trans-hydrindanes and decalins, structural motifs embedded within a plethora of natural products. The last section describes chemoselective alkylations and acylations of C- and N-metalated nitriles that offer the tantalizing possibility of selectively manipulating functional groups in bioactive medicinal leads without recourse to protecting groups. Collectively, the unusual reactivity profiles of C- and N-metalated nitriles provide new strategies for rapidly and selectively accessing valuable synthetic precursors.
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Affiliation(s)
- Xun Yang
- Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Fraser F. Fleming
- Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, United States
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7
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Nerush A, Vogt M, Gellrich U, Leitus G, Ben-David Y, Milstein D. Template Catalysis by Metal–Ligand Cooperation. C–C Bond Formation via Conjugate Addition of Non-activated Nitriles under Mild, Base-free Conditions Catalyzed by a Manganese Pincer Complex. J Am Chem Soc 2016; 138:6985-97. [DOI: 10.1021/jacs.5b13208] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
| | - Matthias Vogt
- Institut
für Anorganische Chemie und Kristallographie, Universität Bremen, Leobener Straße, 28359 Bremen, Germany
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8
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Xiao J, Yang J, Chen T, Han LB. Nickel-Catalyzed α-Benzylation of Arylacetonitriles via
CO Activation. Adv Synth Catal 2016. [DOI: 10.1002/adsc.201500822] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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9
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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.
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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
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10
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Qin W, Long S, Bongini A, Panunzio M. α-Alkyl-α-aryl (Trimethyltin) Nitriles: Versatile Nucleophilic Intermediates in Aldol-Like Reactions. European J Org Chem 2015. [DOI: 10.1002/ejoc.201500299] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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11
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Bhaskara Rao VU, Kumar K, Singh RP. An efficient aldol-type direct reaction of isatins with TMSCH2CN. Org Biomol Chem 2015; 13:9755-9. [DOI: 10.1039/c5ob01560j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cesium fluoride catalyzed direct cyanomethylation of various isatins by using trimethylsilyl acetonitrile (TMSAN) as a nucleophile has been developed. The reaction has been explored for a number of isatins, with various substitutions on its aromatic ring. Further, the versatility of the reaction is demonstrated by converting the direct aldol adducts to various corresponding intermediates.
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Affiliation(s)
- V. U. Bhaskara Rao
- Department of Chemistry
- Indian Institute of Technology
- New Delhi
- India 110016
| | - Krishna Kumar
- Department of Chemistry
- Indian Institute of Technology
- New Delhi
- India 110016
| | - Ravi P. Singh
- Department of Chemistry
- Indian Institute of Technology
- New Delhi
- India 110016
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12
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Bixa T, Hunter R, Andrijevic A, Petersen W, Su H, Dhoro F. Stereoselective formation of quaternary stereogenic centers via alkylation of α-substituted malonate-imidazolidinones. J Org Chem 2014; 80:762-9. [PMID: 25485811 DOI: 10.1021/jo502140d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new stereoselective alkylation methodology is presented for formation of chiral, nonracemic quaternary centers via a chiral auxiliary protocol involving α-alkylated malonate imidazolidinones. Based on two X-ray structures of quaternized products, the diastereoselectivity observed may be rationalized via a transition-state involving an s-transC-N conformation of the C-N bond of the auxiliary, with the metal cation (K(+)) chelated into the malonate six-membered hole as a Z-enolate. A deprotection protocol involving ethanethiolate exchange of the imide to the corresponding thioester, followed by a standard Fukuyama reduction and a borohydride reduction, furnishes α,α'-quaternized β-hydroxypropionates in high ee overall.
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Affiliation(s)
- Thobela Bixa
- Department of Chemistry, University of Cape Town , Rondebosch 7701, South Africa
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13
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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]
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14
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Li H, Zhang Y, Xie X, Ma H, Zhao C, Zhao G, She X. Bioinspired Total Synthesis of Gymnothelignan N. Org Lett 2014; 16:4440-3. [DOI: 10.1021/ol501960j] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Huilin Li
- State
Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, People’s Republic of China
| | - Yuanyuan Zhang
- State
Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, People’s Republic of China
| | - Xingang Xie
- State
Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, People’s Republic of China
| | - Haichen Ma
- State
Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, People’s Republic of China
| | - Changgui Zhao
- State
Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, People’s Republic of China
| | - Gaoyuan Zhao
- State
Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, People’s Republic of China
| | - Xuegong She
- State
Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, People’s Republic of China
- State
Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Lanzhou 730000, People’s Republic of China
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15
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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]
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16
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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]
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17
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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]
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18
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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]
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19
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Mycka RJ, Eckenhoff WT, Steward OW, Barefoot NZ, Fleming FF. γ- and δ-Hydroxynitriles: diastereoselective electrophile-dependent alkylations. Tetrahedron 2013. [DOI: 10.1016/j.tet.2012.10.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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20
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Das JP, Marek I. Enantioselective synthesis of all-carbon quaternary stereogenic centers in acyclic systems. Chem Commun (Camb) 2011; 47:4593-623. [DOI: 10.1039/c0cc05222a] [Citation(s) in RCA: 563] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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21
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Hodgson DM, Arif T. Convergent synthesis of trisubstituted Z-allylic esters by Wittig-Schlosser reaction. Org Lett 2010; 12:4204-7. [PMID: 20722384 DOI: 10.1021/ol101843q] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
β-Lithiooxyphosphonium ylides, generated in situ from aldehydes and Wittig reagents, react readily with halomethyl esters to form trisubstituted Z-allylic esters. The methodology was applied to a total synthesis of the geranylgeraniol-derived diterpene (6S,7R,Z)-7-hydroxy-2-((E)-6-hydroxy-4-methylhex-4-enylidene)-6,10-dimethylundec-9-enyl acetate (12).
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Affiliation(s)
- David M Hodgson
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom.
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22
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Mycka RJ, Steward OW, Fleming FF. γ-Hydroxynitrile Alkylations: Electrophile-Dependent Stereoselectivity. Org Lett 2010; 12:3030-3. [DOI: 10.1021/ol101030r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Robert J. Mycka
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530
| | - Omar W. Steward
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530
| | - Fraser F. Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282-1530
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23
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García Ruano J, Martín-Castro A, Tato F, Torrente E, Poveda A. Stereodivergent Quaternization of 2-Alkyl-2-p-tolylsulfinylacetonitriles: NMR Spectroscopic Evidence of Planar and Pyramidal Benzylic Carbanions. Chemistry 2010; 16:6317-25. [DOI: 10.1002/chem.200903521] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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24
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Abstract
Palladium-catalyzed decarboxylative alpha-allylation of nitriles readily occurs with use of Pd(2)(dba)(3) and rac-BINAP. This catalyst mixture also allows the highly regiospecific alpha-allylation of nitriles in the presence of much more acidic alpha-protons. Thus, the reported method provides access to compounds that are not readily available via base-mediated allylation chemistries. Lastly, mechanistic investigations indicate that there is a competition between C- and N-allylation of an intermediate nitrile-stabilized anion and that N-allylation is followed by a rapid [3,3]-sigmatropic rearrangement.
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Affiliation(s)
- Antonio Recio
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045
| | - Jon A. Tunge
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045
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25
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Kamata K, Hirano T, Kuzuya S, Mizuno N. Hydrogen-bond-assisted epoxidation of homoallylic and allylic alcohols with hydrogen peroxide catalyzed by selenium-containing dinuclear peroxotungstate. J Am Chem Soc 2009; 131:6997-7004. [PMID: 19408944 DOI: 10.1021/ja901289r] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reaction of peroxotungstates (H(2)WO(4) + H(2)O(2)) with H(2)SeO(4) gave the novel selenium-containing dinuclear tungsten species, (TBA)(2)[SeO(4){WO(O(2))(2)}(2)] (I, TBA = [(n-C(4)H(9))(4)N](+)), which was characterized by elemental analysis, IR, Raman, UV-vis, (77)Se NMR, (183)W NMR, and CSI-MS. Various kinds of homoallylic and allylic alcohols were efficiently epoxidized to the corresponding epoxy alcohols in high yields with 1 equiv. H(2)O(2) with respect to the substrates. Compound I showed the highest catalytic activity for H(2)O(2)-based epoxidation of homoallylic and allylic alcohols among selenium and tungsten complexes. The turnover frequency reached up to 150 h(-1) in a 10 mmol-scale epoxidation of cis-3-hexen-1-ol and this value was the highest among those reported for the transition-metal catalyzed epoxidation of homoallylic alcohols with H(2)O(2). The kinetic, mechanistic, computational studies showed that the stabilization of the transition-state by the hydrogen bonding between I and the substrates results in the high reactivity for the I-catalyzed epoxidation of homoallylic and allylic alcohols. The nature of the hetero atoms in the di- and tetranuclear peroxotungstates with XO(4)(n-) ligands (X = As(V), P(V), S(VI), Si(IV), etc.) was crucial in controlling the Lewis acidity of the peroxotungstates, which significantly affects their electrophilic oxygen transfer reactivity. All the data of the structural, kinetic, spectroscopic, and computational comparison show that the dimeric peroxotungstate unit, {WO(O(2))(2)}(2), in I is activated by the SeO(4)(2-) ligand.
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Affiliation(s)
- Keigo Kamata
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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