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Duhamel T, Scaringi S, Leforestier B, Poblador-Bahamonde AI, Mazet C. Assisted Tandem Pd Catalysis Enables Regiodivergent Heck Arylation of Transiently Generated Substituted Enol Ethers. JACS Au 2023; 3:261-274. [PMID: 36711081 PMCID: PMC9875267 DOI: 10.1021/jacsau.2c00645] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/19/2022] [Accepted: 12/19/2022] [Indexed: 06/18/2023]
Abstract
Two complementary regiodivergent Pd-catalyzed assisted tandem [isomerization/Heck arylation] reactions are reported. They provide access to a broad array of acyclic trisubstituted vinyl ethers starting from readily available alkenyl ethers. In both cases, the isomerization is conducted with a [Pd-H] precatalyst supported by tris-tert-butyl phosphine ligands. When the catalyst is modified by the addition of a chelating bisphosphine ligand (dppp), an organic base (Cy2NMe), sodium acetate, and aryl triflates are used as electrophiles, the α-arylation pathway is promoted preferentially. The β-arylation pathway is favored for electron-deficient and electron-neutral aryl halides when the catalyst is simply modified by the addition of an excess of an organic base (Et3N) after completion of the isomerization reaction. Electron-rich aryl halides lead to reduced levels of regiocontrol. The moderate stereoselectivity obtained are proposed to reflect the absence of stereocontrol in the isomerization step. Computational analyses suggest that migratory insertion is selectivity-determining for both the arylations. For the β-selective arylation, an energy decomposition analysis underscored that electronic factors favor α-regioselectivity and steric effects favor β-regioselectivity. Preliminary investigations show that high levels of stereoselectivity can be achieved for the α-selective arylation by ligand control. Complementarily, reaction conditions for postcatalytic stereo-correction have also been identified for each catalytic system.
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Viñas-Lóbez J, Levitre G, de Aguirre A, Besnard C, Poblador-Bahamonde AI, Lacour J. Enabling Cyclization Strategies through Carbonyl-Ylide-Mediated Synthesis of Malonate Enol Ethers. ACS Org Inorg Au 2021; 1:11-17. [PMID: 36855638 PMCID: PMC9954264 DOI: 10.1021/acsorginorgau.1c00006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Malonate enol ethers are afforded in one step by condensation of cyclic ketones with α-diazomalonates under [CpRu(CH3CN)3][BArF] catalysis. The dual reactivity of these 2-vinyloxymalonates can be used to expand the classical range of cyclizations derived from carbonyl ylide intermediates.
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Affiliation(s)
- Júlia Viñas-Lóbez
- Department
of Organic Chemistry and Laboratoire de Cristallographie, University of Geneva, Geneva CH-1211, Switzerland
| | - Guillaume Levitre
- Department
of Organic Chemistry and Laboratoire de Cristallographie, University of Geneva, Geneva CH-1211, Switzerland
| | - Adiran de Aguirre
- Department
of Organic Chemistry and Laboratoire de Cristallographie, University of Geneva, Geneva CH-1211, Switzerland
| | - Céline Besnard
- Department
of Organic Chemistry and Laboratoire de Cristallographie, University of Geneva, Geneva CH-1211, Switzerland
| | - Amalia I. Poblador-Bahamonde
- Department
of Organic Chemistry and Laboratoire de Cristallographie, University of Geneva, Geneva CH-1211, Switzerland
| | - Jérôme Lacour
- Department
of Organic Chemistry and Laboratoire de Cristallographie, University of Geneva, Geneva CH-1211, Switzerland
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Declas N, Waser J. Access to Vinyl Ethers and Ketones with Hypervalent Iodine Reagents as Oxy-Allyl Cation Synthetic Equivalents. Angew Chem Int Ed Engl 2020; 59:18256-18260. [PMID: 32542955 DOI: 10.1002/anie.202006707] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/08/2020] [Indexed: 12/18/2022]
Abstract
We report an Umpolung strategy of enol ethers to generate oxy-allyl cation equivalents based on the use of hypervalent iodine reagents. Under mild basic conditions, the addition of nucleophiles to aryloxy-substituted vinylbenziodoxolone (VBX) reagents, easily available in two steps from silyl alkynes, resulted in the stereoselective formation of substituted aryl enol ethers. The reaction was most efficient with phenols as nucleophiles, but preliminary results were also achieved for C- and N- nucleophiles. In absence of external nucleophiles, the 2-iodobenzoate group of the reagent was transferred. The obtained aryl enol ethers could then be transformed into α-difunctionalized ketones by oxidation. The described "allyl cation"-like reactivity contrast with the well-established "vinyl-cation" behavior of alkenyl iodonium salts.
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Affiliation(s)
- Nina Declas
- Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306, 1015, Lausanne, Switzerland
| | - Jerome Waser
- Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306, 1015, Lausanne, Switzerland
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Verhoeven J, De Vleeschouwer F, Kong H, Van Hecke K, Pande V, Sun W, Vos A, Wu T, Meerpoel L, Thuring JW, Verniest G. Preparation of 4'-Spirocyclobutyl Nucleoside Analogues as Novel and Versatile Adenosine Scaffolds. Chemistry 2019; 25:15419-15423. [PMID: 31609050 DOI: 10.1002/chem.201904574] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Indexed: 11/10/2022]
Abstract
Despite the large variety of modified nucleosides that have been reported, the preparation of constrained 4'-spirocyclic adenosine analogues has received very little attention. We discovered that the [2+2]-cycloaddition of dichloroketene on readily available 4'-exo-methylene furanose sugars efficiently results in the diastereoselective formation of novel 4'-spirocyclobutanones. The reaction mechanism was investigated via density functional theory (DFT) and found to proceed either via a non-synchronous or stepwise reaction sequence, controlled by the stereochemistry at the 3'-position of the sugar substrate. The obtained dichlorocyclobutanones were converted into nucleoside analogues, providing access to a novel class of chiral 4'-spirocyclobutyl adenosine mimetics in eight steps from commercially available sugars. Assessment of the biological activity of designed 4'-spirocyclic adenosine analogues identified potent inhibitors for protein methyltransferase target PRMT5.
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Affiliation(s)
- Jonas Verhoeven
- Research Group of Organic Chemistry (ORGC), Department of Chemistry and Department of Bio-engineering Sciences, Faculty of Science and Bio-engineering Sciences, Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050, Brussels, Belgium
| | - Freija De Vleeschouwer
- Research Group of Organic Chemistry (ORGC), Department of Chemistry and Department of Bio-engineering Sciences, Faculty of Science and Bio-engineering Sciences, Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050, Brussels, Belgium.,Research Group of General Chemistry (ALGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - Hanchu Kong
- Department of Synthetic Chemistry, Pharmaron Beijing Co., Ltd., 6 Taihe Road BDA, Beijing, 100176, P. R. China
| | - Kristof Van Hecke
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000, Ghent, Belgium
| | - Vineet Pande
- Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340, Beerse, Belgium
| | - Weimei Sun
- Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340, Beerse, Belgium
| | - Ann Vos
- Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340, Beerse, Belgium
| | - Tongfei Wu
- Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340, Beerse, Belgium
| | - Lieven Meerpoel
- Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340, Beerse, Belgium
| | | | - Guido Verniest
- Research Group of Organic Chemistry (ORGC), Department of Chemistry and Department of Bio-engineering Sciences, Faculty of Science and Bio-engineering Sciences, Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050, Brussels, Belgium.,Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340, Beerse, Belgium
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Schütznerová E, Krchňáková A, Krchňák V. Traceless Solid-Phase Synthesis of Ketones via Acid-Labile Enol Ethers: Application in the Synthesis of Natural Products and Derivatives. Molecules 2019; 24:E1406. [PMID: 30974778 DOI: 10.3390/molecules24071406] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 04/04/2019] [Accepted: 04/08/2019] [Indexed: 11/17/2022] Open
Abstract
In solid-phase organic synthesis, Wang resin is traditionally used for the immobilization of acids, alcohols, phenols, and amines. We report the use of Wang resin for the traceless synthesis of ketones via acid-labile enol ethers. We demonstrate the practicality of this synthetic strategy on the solid-phase synthesis of pyrrolidine-2,4-diones, which represent the core structure of several natural products, including tetramic acid. Base-triggered condensation of pyrrolidine-2,4-diones yielded 4-hydroxy-1,1',2',5-tetrahydro-2H,5'H-[3,3'-bipyrrole]-2,5'-diones.
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Schitter T, Jones PG, Werz DB. Intramolecular Pd-Catalyzed Formal anti-Carboalkoxylation of Alkynes: Access to Tetrasubstituted Enol Ethers. Chemistry 2018; 24:13446-13449. [PMID: 30035827 DOI: 10.1002/chem.201803721] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Indexed: 11/11/2022]
Abstract
An intramolecular Pd-catalyzed formal anti-carboalkoxylation reaction is presented that provides access to tetrasubstituted enol ethers. The key to success is a cascade consisting of a formal anti-carbopalladation of a carbon-carbon triple bond followed by a nucleophilic attack of a hydroxy group at the emerging vinyl organopalladium species. The desired transformation proceeded smoothly with primary, secondary, and tertiary alcohols, and even with phenols. Depending on the substitution pattern of the enol ethers, a further Tsuji-Trost-type step may occur resulting in oligocyclic ketals.
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Affiliation(s)
- Theresa Schitter
- Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106, Braunschweig, Germany
| | - Peter G Jones
- Technische Universität Braunschweig, Institute of Inorganic and Analytical Chemistry, Hagenring 30, 38106, Braunschweig, Germany
| | - Daniel B Werz
- Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106, Braunschweig, Germany
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Nishimoto Y, Nishimura T, Yasuda M. Indium Tribromide Catalyzed Coupling Reaction of Enol Ethers with Silyl Ketene Imines toward the Synthesis of β,γ-Unsaturated Nitriles. Chemistry 2015; 21:18301-8. [PMID: 26515612 DOI: 10.1002/chem.201503414] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Indexed: 11/12/2022]
Abstract
Herein, a coupling reaction of enol ethers with silyl ketene imines in the presence of catalytic amounts of InBr3 and Me3 SiBr is described. Kinetic studies have revealed that an indium catalyst and Me3 SiBr accelerated the coupling process and the regeneration of the catalyst, respectively. Various types of enol ethers and silyl ketene imines are applicable. In addition, a formal synthesis of verapamil was achieved by using this novel coupling reaction.
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Affiliation(s)
- Yoshihiro Nishimoto
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan). .,Frontier Research Base for Young Researchers, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan).
| | - Takashi Nishimura
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)
| | - Makoto Yasuda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan).
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Tarabová D, Soralová S, Breza M, Fronc M, Holzer W, Milata V. Use of activated enol ethers in the synthesis of pyrazoles: reactions with hydrazine and a study of pyrazole tautomerism. Beilstein J Org Chem 2014; 10:752-60. [PMID: 24778729 PMCID: PMC3999851 DOI: 10.3762/bjoc.10.70] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 03/14/2014] [Indexed: 12/03/2022] Open
Abstract
Activated enol ethers derived from esters or the dinitrile of malonic acid, or from pentane-2,4-dione were treated with hydrazine hydrate. The structures of the obtained products – pyrazoles 5 – were studied with a focus on tautomerism and supramolecular structure. A reverse addition of the reagents led to the isolation of two novel products, namely bis-enehydrazines 6 with an unsymmetrical arrangement of the formally equivalent subunits.
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Affiliation(s)
- Denisa Tarabová
- Department of Organic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava, Slovakia
| | - Stanislava Soralová
- Department of Physical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava, Slovakia ; Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovakia
| | - Martin Breza
- Department of Physical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava, Slovakia
| | - Marek Fronc
- Department of Physical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava, Slovakia
| | - Wolfgang Holzer
- Department of Drug and Natural Product Synthesis, Vienna University, Althanstrasse 14, A-1090 Vienna, Austria
| | - Viktor Milata
- Department of Organic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava, Slovakia
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Abstract
A route enabling the synthesis of the stereo-triad of rishirilide B (1) from 2-hydroxy-3-methylnaphthalene-1,4-dione, is reported. Key transformations include the regioselective 1,2-Grignard addition to a tautomeric mixture of o- and p-quinones, regioselective carbamoylation of a tautomeric mixture, and a synopsis of the methods explored to convert various terminal vinyl ethers into the corresponding carboxylic acid by cleavage.
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Affiliation(s)
- Lupe Mejorado
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, CA 93106-9510, USA, Fax +1(805)6375651; E-mail:
| | - Thomas R. R. Pettus
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, CA 93106-9510, USA, Fax +1(805)6375651; E-mail:
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