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Selective Electrochemical Halogenation of Functionalized Quinolone. J Org Chem 2023; 88:12958-12970. [PMID: 37620989 DOI: 10.1021/acs.joc.3c00876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
This work describes an effective C3-H halogenation of quinoline-4(1H)-ones under electrochemical conditions, in which potassium halides serve as both halogenating agents and electrolytes. The protocol provides expedient access to different halogenated quinoline-4(1H)-ones with unique regioselectivity, broad substrate scope, and gram-scale synthesis employing convenient, environmentally friendly electrolysis, in an undivided cell. Mechanism studies have shown that halogen radicals can promote the activation of N-H bonds in quinolones.
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2
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Direct C−H Arylation of Quinoxalin‐2(
H
)‐ones with Arylhydrazine hydrochlorides. ChemistrySelect 2023. [DOI: 10.1002/slct.202204611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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3
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Regioselective Perfluoroalkylation of 4‐Quinolones Using Sodium Perfluoroalkyl Sulfinates. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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4
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Recent Advances in Organic Synthesis of 3-Amino- or 4-Aminocoumarins. MINI-REV ORG CHEM 2022. [DOI: 10.2174/1570193x18666211001124004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
:
Coumarin is a privileged scaffold that contains the unique 2H-chromen-2-one motif, and its
derivatives are widely distributed in nature, especially in plants. In recent years, due to their diverse
pharmacological activities and remarkable photochemical properties, they have attracted significant
attention from scientists, which has also prompted the research on the synthesis approaches and the
availability of substrates for these compounds. This article is a brief description of the methods for the
synthesis of various coumarin derivatives via two- or multi-component reactions involving 3-amino
or 4-aminocoumarin reported during 2015-2021. This review may help expand the development of
various analogues with coumarin as the basic unit.
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Electrochemical Oxidative C-H Arylation of Quinoxalin(on)es with Arylhydrazine Hydrochlorides under Mild Conditions. J Org Chem 2022; 87:4764-4776. [PMID: 35319891 DOI: 10.1021/acs.joc.2c00043] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A practical and scalable protocol for electrochemical arylation of quinoxalin(on)es with arylhydrazine hydrochlorides under mild conditions has been developed. This method exhibits high efficiency, easy scalability, and broad functional group tolerance. Various quinoxalin(on)es and arylhydrazines underwent this transformation smoothly in an undivided cell, providing the corresponding aryl-substituted quinoxalin(on)es in moderate to good yields. A radical mechanism is involved in this arylation reaction.
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6
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Direct C‐2 arylation of quinoxaline with arylhydrazine salts as arylation reagents. J Heterocycl Chem 2022. [DOI: 10.1002/jhet.4465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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7
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Dual Role of Oxoaldehydes: Divergent Synthesis of 3-Aryl- and 3-Aroylcoumarins. J Org Chem 2022; 87:3630-3637. [PMID: 35112865 DOI: 10.1021/acs.joc.1c02159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A facile and efficient synthetic approach to various valuable 3-aryl- and 3-aroylcoumarins by the direct arylation and aroylation of coumarins with glyoxals in a metal-free manner is presented. The aryl glyoxal is for the first time recognized to serve as an aryl surrogate in addition to its role as an aroyl transfer reagent via a simple switch in reaction conditions. The approach accommodates a broad substrate scope and high yields of the two types of cross-coupling reactions starting from identical starting materials.
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8
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Hypervalent Iodine(III)-Promoted C3-H Regioselective Halogenation of 4-Quinolones under Mild Conditions. ACS OMEGA 2021; 6:34044-34055. [PMID: 34926952 PMCID: PMC8675166 DOI: 10.1021/acsomega.1c05455] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 11/17/2021] [Indexed: 06/14/2023]
Abstract
A simple and practical protocol for the C3-H regioselective halogenation of 4-quinolones by the action of potassium halide salt and PIFA/PIDA in good to excellent yields was developed. The current approach provides feasible access to the diversity of C3-halgenated 4-quinolones at room temperature with high regioselectivity and good functional group tolerance, from which bioactive compounds can be easily constructed. Moreover, the current method featured eco-friendly, operational convenience and is suitable for halogenation in a gram scale of 4-quinolones in water without sacrificing yields.
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9
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Recent Advances in the Transition-Metal-Free Arylation of Heteroarenes. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/a-1543-3743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AbstractTransition-metal-free arylation reactions have attracted considerable attention for economic and environmental reasons over the past 40 years. In recent years, much effort has been made to develop efficient transition-metal-free approaches for the arylation of heteroarenes. Covering the literature from 2015 to early 2021, this review aims to provide a thorough overview of the synthetic and mechanistic aspects of these atom-economical and environmentally benign reactions.1 Introduction2 Arylation of Pre-functionalized Heteroarenes2.1 Arylation of Heteroaryl Halides2.2 Decarboxylative Arylation of Heteroarenes3 Direct C–H Arylation of Heteroarenes3.1 C(sp2)–H Arylation3.2 C(sp3)–H Arylation4 N-Arylation of Heteroarenes5 Summary and Outlook
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Abstract
The Endochin-Like Quinolone (ELQ) compound class may yield effective, safe treatments for a range of important human and animal afflictions. However, to access the public health potential of this compound series, a synthetic route needed to be devised that lowers costs and is amenable to large scale production. In the new synthetic route described here, a substituted β-keto ester, formed by an Ullmann reaction and subsequent acylation, is reacted with an aniline via a Conrad-Limpach reaction to produce 3-substituted 4(1H)-quinolones such as ELQ-300 and ELQ-316. This synthetic route, the first described to be truly amenable to industrial scale production, is relatively short (5 reaction steps), does not require palladium, chromatographic separation or protecting group chemistry, and may be performed without high vacuum distillation.
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11
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Generation of aryl radicals by redox processes. Recent progress in the arylation methodology. RUSSIAN CHEMICAL REVIEWS 2021. [DOI: 10.1070/rcr4959] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Arylation methods based on the generation and use of aryl radicals have been a rapidly growing field of research in recent years and currently represent a powerful strategy for carbon – carbon and carbon – heteroatom bond formation. The progress in this field is related to advances in the methods for generation of aryl radicals. The currently used aryl radical precursors include aryl halides, aryldiazonium and diaryliodonium salts, arylcarboxylic acids and their derivatives, arylboronic acids, arylhydrazines, organosulfur(II, VI) compounds and some other compounds. Aryl radicals are generated under mild conditions by single electron reduction or oxidation of precursors induced by conventional reagents, visible light or electric current. A crucial role in the development of the radical arylation methodology belongs to photoredox processes either catalyzed by transition metal complexes or organic dyes or proceeding without catalysts. Unlike the conventional transition metal-catalyzed arylation methods, radical arylation reactions proceed very often at room temperature and have high functional group tolerance. Without claiming to be exhaustive, this review covers the most important advances of the current decade in the generation and synthetic applications of (het)aryl radicals. Examples of reactions are given and mechanistic insights are highlighted.
The bibliography includes 341 references.
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Cu-Catalysed synthesis of benzo[f]indole-2,4,9(3H)-triones by the reaction of 2-amino-1,4-napthoquinones with α-bromocarboxylates. Org Biomol Chem 2020; 18:6724-6731. [PMID: 32832951 DOI: 10.1039/d0ob00291g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A copper-catalysed cascade ester amidation/radical cyclization of 2-amino-1,4-naphthoquinones with α-bromocarboxylates to afford benzo[f]indole-2,4,9(3H)-triones is described, and the reaction has a broad substrate scope and the desired products are obtained in mostly moderate to good yields. Mechanism-probing experiments indicate that the otherwise challenging radical coupling reaction of α-bromocarboxylates with 2-amino-1,4-naphthoquinones is facilitated by a 5-endo radical cyclization.
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14
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The C3-H Bond Functionalization of Quinoxalin-2(1 H)-Ones With Hypervalent Iodine(III) Reagents. Front Chem 2020; 8:582. [PMID: 32850624 PMCID: PMC7432307 DOI: 10.3389/fchem.2020.00582] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/05/2020] [Indexed: 12/19/2022] Open
Abstract
The modification of quinoxalin-2(1H)-ones via direct C-H bond functionalization has begun to receive widespread attention, due to quinoxalin-2(1H)-one derivatives' various biological activities and pharmaceutical properties. This mini review concentrates on the accomplishments of arylation, trifluoromethylation, alkylation, and alkoxylation of quinoxalin-2(1H)-ones with hypervalent iodine(III) reagents as reaction partners or oxidants. The reaction conditions and mechanisms are compared and discussed in detail.
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15
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Ligand-free copper-catalyzed denitrogenative arylation of phosphorylamides with arylhydrazines. SYNTHETIC COMMUN 2020. [DOI: 10.1080/00397911.2020.1725577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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16
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Access to 2-Alkyl/Aryl-4-(1 H)-Quinolones via Orthogonal "NH 3" Insertion into o-Haloaryl Ynones: Total Synthesis of Bioactive Pseudanes, Graveoline, Graveolinine, and Waltherione F. Org Lett 2020; 22:1575-1579. [PMID: 32013447 DOI: 10.1021/acs.orglett.0c00172] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
An efficient one-pot synthesis of 4-(1H)-quinolones through an orthogonal engagement of diverse o-haloaryl ynones with ammonia in the presence of Cu(I), involving tandem Michael addition and ArCsp2-N coupling, is presented. The substrate scope of this convenient protocol, wherein ammonium carbonate acts as both an in situ ammonia source and a base toward diverse 2-substituted 4-(1H)-quinolones, has been mapped and its efficacy validated through concise total synthesis of bioactive natural products pseudanes (IV, VII, VIII, and XII), graveoline, graveolinine, and waltherione F.
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17
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Potentially tautomeric 3-arylquinolin-4(1H)-ones and their 4-anilinoquinoline derivatives: Spectroscopic, DFT and X-ray analyses. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2019.126982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Chlorophyll-catalyzed photochemical regioselective coumarin C–H arylation with diazonium salts. NEW J CHEM 2020. [DOI: 10.1039/d0nj02012e] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A metal-free, direct C–H arylation of coumarins with aryl diazonium salts at room temperature using chlorophyll as a green photosensitizer is devised.
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19
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The synthesis of quinolines via denitrogenative palladium-catalyzed cascade reaction of o-aminocinnamonitriles with arylhydrazines. RSC Adv 2020; 10:8586-8593. [PMID: 35496529 PMCID: PMC9050002 DOI: 10.1039/d0ra01043j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 02/20/2020] [Indexed: 11/28/2022] Open
Abstract
The first example of the palladium-catalyzed cascade reaction of o-aminocinnamonitriles with arylhydrazines has been achieved, providing an efficient synthetic pathway to access quinolines with moderate to good yields. Preliminary mechanistic experiments indicate that this cascade process involves sequential denitrogenative addition followed by an intramolecular cyclization. Pd-catalyzed cascade denitrogenative addition and intramolecular cyclization of o-aminocinnamonitriles with arylhydrazine for the synthesis of quinolines.![]()
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20
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New routes for the synthesis of unsymmetrical diarylselenides: Effect of heat, light and ultrasound. MOLECULAR CATALYSIS 2019. [DOI: 10.1016/j.mcat.2019.110534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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21
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Transition metal free K2CO3 mediated thioarylation, selenoarylation and arylation of 2-aminomaleimides at ambient temperature. Tetrahedron 2019. [DOI: 10.1016/j.tet.2019.130486] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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22
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23
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Copper-catalyzed denitrogenative N-arylation of sulfoximines and sulfonamides with arylhydrazines. Tetrahedron 2019. [DOI: 10.1016/j.tet.2019.05.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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NH
4
OAc‐Promoted Cascade Approach towards Aberrant Synthesis of Chromene‐Fused Quinolinones. European J Org Chem 2018. [DOI: 10.1002/ejoc.201801292] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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26
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Arylhydrazines: novel and versatile electrophilic partners in cross-coupling reactions. RSC Adv 2018; 8:33828-33844. [PMID: 35548837 PMCID: PMC9086722 DOI: 10.1039/c8ra06423g] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 09/06/2018] [Indexed: 11/23/2022] Open
Abstract
Arylhydrazines are extremely valuable compounds in organic chemistry that are widely used for the synthesis of a variety of biologically active molecules such as indoles, indazoles, pyrazoles, aryltriazoles, β-lactams and quinazolines. These compounds have also been widely utilized as arylation agents in oxidative cross-coupling reactions. In this review, we will highlight the most important explorations and developments in the carbon-carbon and carbon-heteroatom (nitrogen, phosphorus, sulfur, and selenium) cross-coupling of arylhydrazines. The literature has been surveyed from 2001 to June 2018.
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27
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A Novel Approach to Access Aryl Iodides and Disulfides via Dehydrazination of Arylhydrazines and Arylsulfonylhydrazides. ChemistrySelect 2018. [DOI: 10.1002/slct.201800188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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28
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29
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Substrate selective synthesis of indole, tetrahydroquinoline and quinoline derivatives via intramolecular addition of hydrazones and imines. Org Chem Front 2018. [DOI: 10.1039/c7qo01115f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
A transition-metal-free, substrate selective synthesis of 2,3-diaryl indoles, 4-hydrazono-tetrahydroquinolines and substituted quinolines has been developed.
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Hydroxyl directed C-arylation: synthesis of 3-hydroxyflavones and 2-phenyl-3-hydroxy pyran-4-ones under transition-metal free conditions. Org Biomol Chem 2018; 16:444-451. [DOI: 10.1039/c7ob01929g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydroxyl assisted, efficient, transition-metal free and direct C-arylation of 3-hydroxychromone and 5-hydroxy pyran-4-one moieties in the presence of a base, air as an oxidant and arylhydrazines as arylating agents to furnish highly biologically active 3-hydroxyflavones and 2-phenyl-3-hydroxy pyran-4-ones has been developed.
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Denitrogenative palladium-catalyzed coupling of aryl halides with arylhydrazines under mild conditions. Org Biomol Chem 2018; 16:3282-3288. [DOI: 10.1039/c8ob00305j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A novel, simple, and efficient protocol via Pd(ii)-catalyzed denitrogenative coupling of arylhydrazines with aryl halides under ambient and mild conditions.
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32
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Metal-free C–H arylation of imidazoheterocycles with aryl hydrazines. RSC Adv 2018; 8:12360-12367. [PMID: 35539413 PMCID: PMC9079221 DOI: 10.1039/c8ra01474d] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 03/19/2018] [Indexed: 12/23/2022] Open
Abstract
Metal-free C–H arylation of imidazo[1,2-a]pyridines at C-3 position with arylhydrazines in presence of DBU has been developed at room temperature under ambient air.
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33
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Denitrogenative Pd/Cu‐catalyzed Suzuki‐type Cross‐coupling of Aryltrifluoroborates with Arylhydrazine Hydrochlorides in Water under Room Temperature. Appl Organomet Chem 2017. [DOI: 10.1002/aoc.4203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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34
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Atom‐Economical Synthesis of Unsymmetrical Diaryl Selenides from Arylhydrazines and Diaryl Diselenides. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700938] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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35
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Transition-Metal Catalyst Free Oxidative Radical Arylation of N-Methylpyrrole. ACS OMEGA 2017; 2:5000-5004. [PMID: 31457776 PMCID: PMC6641933 DOI: 10.1021/acsomega.7b00988] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 08/16/2017] [Indexed: 05/09/2023]
Abstract
This study represents an expansion of the application of catalysis in air through conventional coupling and free radical processes. A reactive free aryl radical intermediate was generated via the oxidation of an activated Ar-NH-NH2 bond by air as a simple and readily available oxidant. For this purpose, the usability of phenylhydrazine and phenylhydrazine hydrochloride salt reagents for the direct arylation of pyrrole with aryl radicals was investigated. The facile coupling of N-methylpyrrole with aryl radicals was easily applied for the convenient direct synthesis of C-2 arylated pyrroles without a transition-metal catalyst.
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Highly Regioselective Carbamoylation of Electron-Deficient Nitrogen Heteroarenes with Hydrazinecarboxamides. Org Lett 2017; 19:4850-4853. [DOI: 10.1021/acs.orglett.7b02312] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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37
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Transition Metal-Free Iodosobenzene-Promoted Direct Oxidative 3-Arylation of Quinoxalin-2(H)-ones with Arylhydrazines. Adv Synth Catal 2017. [DOI: 10.1002/adsc.201700070] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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38
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Direct amino-halogenation and aziridination of the 2-quinolone framework by sequential treatment of 3-nitro-2-quinolone with amine and N-halosuccinimide. Tetrahedron 2017. [DOI: 10.1016/j.tet.2017.01.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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39
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Oxidative coupling of 1-(2-methyl-4-phenylquinolin-3-yl)ethanone with ethanol and unexpected deacetylative synthesis of 3-hydroxy quinoline. Org Biomol Chem 2017; 15:1080-1085. [PMID: 28067392 DOI: 10.1039/c6ob02336c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
An efficient one pot method for the synthesis of anti-α,β-epoxy ketones from 1-(2-methyl-4-phenylquinolin-3-yl)ethanone and ethanol has been developed by a modified Darzen reaction. The reaction occurs under oxidative conditions via a cascade sequence of bromination, aldol condensation followed by substitution. The reaction in the presence of NBS and a base however, in the absence of an oxidant, led to the formation of the corresponding 3-hydroxylated product via an unusual rearrangement.
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40
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AgNO3-catalyzed direct C–H arylation of quinolines by oxidative decarboxylation of aromatic carboxylic acids. Org Chem Front 2017. [DOI: 10.1039/c6qo00533k] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
AgNO3-catalyzed direct C–H arylation of quinolines by oxidative decarboxylation of aromatic carboxylic acids to afford aryl quinoline derivatives in moderate yields was described.
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41
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KMnO4-mediated direct C2-selective C−H arylation of quinoline N-oxides with aromatic hydrazines. Tetrahedron 2017. [DOI: 10.1016/j.tet.2016.11.070] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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42
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Acid-promoted denitrogenative Pd-catalyzed addition of arylhydrazines with nitriles at room temperature. Org Chem Front 2017. [DOI: 10.1039/c6qo00634e] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pd(TFA)2-catalyzed denitrogenative addition proceeded with selective C–N bond cleavage of arylhydrazines with nitriles under air at room temperature.
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43
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Efficient construction of 3-arylquinolin-4(1 H )-ones via in situ Meinwald rearrangement/intramolecular reductive cyclization of 2′-nitrochalcone epoxides. Tetrahedron 2016. [DOI: 10.1016/j.tet.2016.09.039] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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44
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Strongly Directing Substituents in the Radical Arylation of Substituted Benzenes. J Org Chem 2016; 81:9785-9791. [DOI: 10.1021/acs.joc.6b01840] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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45
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Regioselective C-3 arylation of coumarins with arylhydrazines via radical oxidation by potassium permanganate. ACTA ACUST UNITED AC 2016. [DOI: 10.1515/znb-2016-0109] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Abstract
An efficient protocol for oxidative C-3 arylation of coumarins with arylhydrazine has been developed using potassium permanganate as an oxidant. The arylated coumarins with different electronic properties were obtained in moderate to good yields. The developed protocol for direct C-3 arylation of coumarins could be extended to quinolinones.
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H2O2/DMSO-Promoted Regioselective Synthesis of 3,3'-Bisimidazopyridinylmethanes via Intermolecular Oxidative C(sp(2))-H Bond Activation of Imidazoheterocycles. J Org Chem 2016; 81:7626-34. [PMID: 27487477 DOI: 10.1021/acs.joc.6b01355] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In the past decade, metal-free approaches for C-C bond formation have attracted a great deal of attention due to their ease of use and low cost. This report represents a novel and metal-free synthesis of 3,3'-bisimidazopyridinylmethanes via intermolecular oxidative C(sp(2))-H bond functionalization of imidazo[1,2-a]pyridines with dimethyl sulfoxide as the carbon synthon (CH2) using H2O2 as a mild oxidant under air. A library of 3,3'-bis(2-arylimidazo[1,2-a]pyridin-3-yl)methanes has been achieved in good to excellent yields. The present methodology has been successfully applied to imidazo[2,1-b]thiazoles and imidazo[2,1-b]benzothiazoles. Furthermore, the current approach was also extended for the synthesis of unsymmetrical 3,3'-bisimidazopyridinylmethanes under optimized reaction conditions. A mechanistic pathway is proposed on the basis of experiments with radical scavengers and DMSO-d6 and ESI-MS observations.
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Transition-metal-free synthesis of thiocyanato- or nitro-arenes through diaryliodonium salts. SYNTHETIC COMMUN 2016. [DOI: 10.1080/00397911.2016.1181764] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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One-Pot Assembly of Fused Heterocycles via
Oxidative Palladium-Catalyzed Cyclization of Arylols and Iodoarenes. Adv Synth Catal 2016. [DOI: 10.1002/adsc.201500925] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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