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Mhaske K, Gangai S, Fernandes R, Kamble A, Chowdhury A, Narayan R. Aerobic Catalytic Cross-Dehydrogenative Coupling of Furans with Indoles Provides Access to Fluorophores with Large Stokes Shift. Chemistry 2024; 30:e202302929. [PMID: 38175849 DOI: 10.1002/chem.202302929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Indexed: 01/06/2024]
Abstract
Sustainability in chemical processes is a crucial aspect in contemporary chemistry with sustainable catalysis as a vital parameter of the same. There has been a renewed focus on utilizing earth-abundant metal catalysts to expand the repertoire of organic reactions. Furan is a versatile heterocycle of natural origin used for multiple applications. However, it has scarcely been used in cross-dehydrogenative coupling. In this work, we have explored the cross-dehydrogentive coupling of furans with indoles using commonly available, inexpensive FeCl3 ⋅ 6H2 O (<0.25 $/g) as catalyst in the presence of so called 'ultimate oxidant' - oxygen, without the need for any external ligand or additive. The reactions were found to be scalable and to work even under partially aqueous conditions. This makes the reaction highly economical, practical, operationally simple and sustainable. The methodology provides direct access to π-conjugated short oligomers consisting of furan, thiophene and indole. These compounds were found to show interesting fluorescence properties with remarkably large Stokes shift (up to 205 nm). Mechanistic investigations reveal that the reaction proceeds through chemoselective oxidation of indole by the metal catalyst followed by nucleophilic trapping by furan.
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Affiliation(s)
- Krishna Mhaske
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa, 403401, India
| | - Shon Gangai
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa, 403401, India
| | - Rushil Fernandes
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa, 403401, India
| | - Angulimal Kamble
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa, 403401, India
| | - Arkaprava Chowdhury
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, 400076, Maharashtra, India
| | - Rishikesh Narayan
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa, 403401, India
- School of Interdisciplinary Life Sciences, Indian Institute of Technology Goa, Farmagudi, Goa, 403401, India
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Akbari A, Seyedi N, Faryabi MS. Design of a new method for the synthesis of novel 2-aryl/alkyl-3H-indol-3-ones. Mol Divers 2024; 28:3-9. [PMID: 35715624 DOI: 10.1007/s11030-022-10464-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/16/2022] [Indexed: 10/18/2022]
Abstract
In this research, a mild, efficient, and general method has been developed to synthesize the new derivatives of 2-aryl/alkyl-3H-indol-3-ones in moderate to excellent yields. This method allowed the syntheses of these compounds via the three-component reaction of anhydride compound, sodium cyanide, and aniline derivatives using acetic anhydride as an organic catalyst in one-pot reactions. The advantages of this method include mild reaction conditions, simple procedures, and easy workup.
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Affiliation(s)
- Ali Akbari
- Department of Chemistry, Faculty of Science, University of Jiroft, Jiroft, P. O. Box 8767161167, Iran.
| | - Neda Seyedi
- Department of Chemistry, Faculty of Science, University of Jiroft, Jiroft, P. O. Box 8767161167, Iran
| | - Muhammad Saleh Faryabi
- Department of Chemistry, Faculty of Science, University of Jiroft, Jiroft, P. O. Box 8767161167, Iran
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Abstract
Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R1R2N-O•. The spin distribution over the nitroxide N and O atoms contributes to the thermodynamic stability of these radicals. The presence of bulky N-substituents R1 and R2 prevents nitroxide radical dimerization, ensuring their kinetic stability. Despite their reactivity toward various transient C radicals, some nitroxides can be easily stored under air at room temperature. Furthermore, nitroxides can be oxidized to oxoammonium salts (R1R2N═O+) or reduced to anions (R1R2N-O-), enabling them to act as valuable oxidants or reductants depending on their oxidation state. Therefore, they exhibit interesting reactivity across all three oxidation states. Due to these fascinating properties, nitroxides find extensive applications in diverse fields such as biochemistry, medicinal chemistry, materials science, and organic synthesis. This review focuses on the versatile applications of nitroxides in organic synthesis. For their use in other important fields, we will refer to several review articles. The introductory part provides a brief overview of the history of nitroxide chemistry. Subsequently, the key methods for preparing nitroxides are discussed, followed by an examination of their structural diversity and physical properties. The main portion of this review is dedicated to oxidation reactions, wherein parent nitroxides or their corresponding oxoammonium salts serve as active species. It will be demonstrated that various functional groups (such as alcohols, amines, enolates, and alkanes among others) can be efficiently oxidized. These oxidations can be carried out using nitroxides as catalysts in combination with various stoichiometric terminal oxidants. By reducing nitroxides to their corresponding anions, they become effective reducing reagents with intriguing applications in organic synthesis. Nitroxides possess the ability to selectively react with transient radicals, making them useful for terminating radical cascade reactions by forming alkoxyamines. Depending on their structure, alkoxyamines exhibit weak C-O bonds, allowing for the thermal generation of C radicals through reversible C-O bond cleavage. Such thermally generated C radicals can participate in various radical transformations, as discussed toward the end of this review. Furthermore, the application of this strategy in natural product synthesis will be presented.
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Affiliation(s)
- Dirk Leifert
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
| | - Armido Studer
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
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Nagare YK, Shah IA, Yadav J, Pawar AP, Rangan K, Choudhary R, Iype E, Kumar I. Electrochemical Oxidative Addition of Nucleophiles on 2-Arylindoles: Synthesis of C2-Heteroquaternary Indolin-3-ones. J Org Chem 2022; 87:15771-15782. [DOI: 10.1021/acs.joc.2c01734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Yadav Kacharu Nagare
- Department of Chemistry, Birla Institute of Technology and Science, Pilani 333031, Rajasthan, India
| | - Imtiyaz Ahmad Shah
- Department of Chemistry, Birla Institute of Technology and Science, Pilani 333031, Rajasthan, India
| | - Jyothi Yadav
- Department of Chemistry, Birla Institute of Technology and Science, Pilani 333031, Rajasthan, India
| | - Amol Prakash Pawar
- Department of Chemistry, Birla Institute of Technology and Science, Pilani 333031, Rajasthan, India
| | - Krishnan Rangan
- Department of Chemistry, Birla Institute of Technology and Science, Hyderabad 500078, Telangana, India
| | | | - Eldhose Iype
- College of Engineering and Technology, American University of the Middle East, Egaila 54200, Kuwait
| | - Indresh Kumar
- Department of Chemistry, Birla Institute of Technology and Science, Pilani 333031, Rajasthan, India
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Xiong T, Zhou X, Jiang J. Dearomative oxyphosphorylation of indoles enables facile access to 2,2-disubstituted indolin-3-ones. Org Biomol Chem 2022; 20:5721-5725. [PMID: 35842851 DOI: 10.1039/d2ob01063a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A highly efficient oxidative dearomatization of indoles with H-phosphorus oxides in the presence of TEMPO oxoammonium salt has been demonstrated. Through the intramolecular oxidative dearomatization of indoles and subsequent intermolecular nucleophilic addition with phosphorus nucleophile, a variety of structurally diverse arylphosphoryl and alkylphosphoryl indolin-3-ones were obtained in good yields with a broad substrate scope and high functional-group compatibility.
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Affiliation(s)
- Ting Xiong
- School of Chemistry and Chemical Engineering, Guangxi Key Laboratory of Electrochemical Energy Materials, Guangxi University, Nanning, 530004, P. R. China.
| | - Xingcui Zhou
- School of Chemistry and Chemical Engineering, Guangxi Key Laboratory of Electrochemical Energy Materials, Guangxi University, Nanning, 530004, P. R. China.
| | - Jun Jiang
- School of Chemistry and Chemical Engineering, Guangxi Key Laboratory of Electrochemical Energy Materials, Guangxi University, Nanning, 530004, P. R. China.
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Cremer C, Patureau FW. O 2-Mediated Te(II)-Redox Catalysis for the Cross-Dehydrogenative Coupling of Indoles. JACS AU 2022; 2:1318-1323. [PMID: 35783164 PMCID: PMC9241012 DOI: 10.1021/jacsau.2c00193] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/19/2022] [Accepted: 05/20/2022] [Indexed: 05/09/2023]
Abstract
Very few elements in the periodic system can catalytically activate O2, such as in the context of cross-dehydrogenative couplings. The development of O2-activating catalysts is essential to enable new and sustainable reactivity concepts to emerge, because these catalysts also often feature specific activating interactions with the target substrates. In this context, the unprecedented Te(II)/Te(III) catalyzed dehydrogenative C3-C2 dimerization of indoles is described herein. The fact that O2 can be directly utilized as a terminal oxidant in this reaction, as well as the absence of any background reactivity without the redox-active Te catalyst, constitute very important milestones for the fields of cross-dehydrogenative couplings and tellurium catalysis.
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Yamashiro T, Abe T, Sawada D. Synthesis of 2-monosubstituted indolin-3-ones by cine-substitution of 3-azido-2-methoxyindolines. Org Chem Front 2022. [DOI: 10.1039/d2qo00048b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report herein the formal cine-substitution/hydrolysis of 3-azidoindole intermediates generated from 3-azido-2-methoxyindolines (AZINs). This protocol enables the introduction of both various carboxylic acid and alcohol into indolin-3-ones at the C2-position,...
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Xu F, Smith MW. A general approach to 2,2-disubstituted indoxyls: total synthesis of brevianamide A and trigonoliimine C. Chem Sci 2021; 12:13756-13763. [PMID: 34760160 PMCID: PMC8549782 DOI: 10.1039/d1sc03533a] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/15/2021] [Indexed: 12/11/2022] Open
Abstract
The indoxyl unit is a common structural motif in alkaloid natural products and bioactive compounds. Here, we report a general method that transforms readily available 2-substituted indoles into 2,2-disubstituted indoxyls via nucleophile coupling with a 2-alkoxyindoxyl intermediate and showcase its utility in short total syntheses of the alkaloids brevianamide A (7 steps) and trigonoliimine C (6 steps). The developed method is operationally simple and demonstrates broad scope in terms of nucleophile identity and indole substitution, tolerating 2-alkyl substituents and free indole N-H groups, elements beyond the scope of most prior approaches. Spirocyclic indoxyl products are also accessible via intramolecular nucleophilic trapping.
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Affiliation(s)
- Fan Xu
- Department of Biochemistry, UT Southwestern Medical Center 5323 Harry Hines Blvd Dallas Texas 75390 USA
| | - Myles W Smith
- Department of Biochemistry, UT Southwestern Medical Center 5323 Harry Hines Blvd Dallas Texas 75390 USA
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Wang Z, Xu S, Wang K, Kong N, Liu X. Recent Studies of Bifunctionalization of Simple Indoles. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100280] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Zhan‐Yong Wang
- School of Pharmacy Xinxiang University Xinxiang Henan 453003 P. R. China
| | - Shaohong Xu
- School of Pharmacy Xinxiang University Xinxiang Henan 453003 P. R. China
| | - Kai‐Kai Wang
- School of Pharmacy Xinxiang University Xinxiang Henan 453003 P. R. China
| | - Niuniu Kong
- School of Pharmacy Xinxiang University Xinxiang Henan 453003 P. R. China
| | - Xue Liu
- Department of Chemistry Lishui University Zhejiang P. R. China
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Shinde MH, Ramana CV. An Apparent Umpolung Reactivity of Indole through [Au]-Catalysed Cyclisation and Lewis-Acid-Mediated Allylation. Chemistry 2020; 26:17171-17175. [PMID: 32970893 DOI: 10.1002/chem.202003441] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/07/2020] [Indexed: 11/10/2022]
Abstract
The sequential functionalization of indole C2 and C3 in an umpolung fashion was executed with a predesigned substrate and choice of reagents. The developed method comprises gold-catalysed alkynol cycloisomerisation/intramolecular addition of C2 of indole and subsequent BF3 ⋅OEt2 -mediated regioselective C3 allylation, resulting in the synthesis of the functionalized indoloisoquinolinone scaffold. The reaction involves 5-endo-alkynol cycloisomerisation and the dearomative addition of indole C2 to the intermediate oxocarbenium cation, which results in two equilibrating fused and spiropentacyclic intermediates, which upon treatment with allyl silane in the presence of BF3 ⋅OEt2 , undergo selective indole C3 allylation. Other nucleophiles, such as hydride, azide and indole, were also found to be compatible with this process.
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Affiliation(s)
- Mahesh H Shinde
- Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Anusandhan Bhawan, 2 Rafi Marg, New Delhi, 110002, India
| | - Chepuri V Ramana
- Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Anusandhan Bhawan, 2 Rafi Marg, New Delhi, 110002, India
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Advances in Cross-Coupling Reactions. MOLECULES (BASEL, SWITZERLAND) 2020; 25:molecules25194500. [PMID: 33019540 PMCID: PMC7582370 DOI: 10.3390/molecules25194500] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 11/16/2022]
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Yan X, Tang YD, He F, Yu SJ, Liu X, Bao J, Zhang H. Synthesis and assessment of bisindoles as a new class of antibacterial agents. MONATSHEFTE FUR CHEMIE 2020. [DOI: 10.1007/s00706-020-02629-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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