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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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Wei J, Zhang J, Cheng JK, Xiang SH, Tan B. Modular enantioselective access to β-amino amides by Brønsted acid-catalysed multicomponent reactions. Nat Chem 2023; 15:647-657. [PMID: 37055574 DOI: 10.1038/s41557-023-01179-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 03/13/2023] [Indexed: 04/15/2023]
Abstract
β-Amino acids are structural motifs widely found in therapeutic natural products, novel biomimetic polymers and peptidomimetics. As a convergent method, the synthesis of stereoenriched β-amino amides through the asymmetric Mannich reaction requires specialized amide substrates or a metal catalyst for enolate formation. By a redesign of the Ugi reaction, a conceptually different solution to prepare chiral β-amino amides was established using ambiphilic ynamides as two-carbon synthons. The modulation of ynamides or oxygen nucleophiles concisely furnished three classes of β-amino amides with generally good efficiency as well as excellent chemo- and stereo-control. The utility is verified in the preparation of over 100 desired products that bear one or two contiguous carbon stereocentres, including those that directly incorporate drug molecules. This advance also provides a synthetic shortcut to other valuable structures. The amino amides could be elaborated into β-amino acids, anti-vicinal diamines, γ-amino alcohols and β-lactams or undergo transamidation with amino acids and amine-containing pharmaceuticals.
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Affiliation(s)
- Jun Wei
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen, China
| | - Jian Zhang
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen, China
| | - Jun Kee Cheng
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen, China
| | - Shao-Hua Xiang
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen, China.
- Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen, China.
| | - Bin Tan
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen, China.
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3
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Feng M, Zhang H, Maulide N. Challenges and Breakthroughs in Selective Amide Activation. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 134:e202212213. [PMID: 38504998 PMCID: PMC10947092 DOI: 10.1002/ange.202212213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Indexed: 11/09/2022]
Abstract
In contrast to ketones and carboxylic esters, amides are classically seen as comparatively unreactive members of the carbonyl family, owing to their unique structural and electronic features. However, recent decades have seen the emergence of research programmes focused on the selective activation of amides under mild conditions. In the past four years, this area has continued to rapidly develop, with new advances coming in at a fast pace. Several novel activation strategies have been demonstrated as effective tools for selective amide activation, enabling transformations that are at once synthetically useful and mechanistically intriguing. This Minireview comprises recent advances in the field, highlighting new trends and breakthroughs in what could be called a new age of amide activation.
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Affiliation(s)
- Minghao Feng
- Faculty of ChemistryInstitute of Organic ChemistryUniversity of ViennaWähringer Straße 381090ViennaAustria
| | - Haoqi Zhang
- Faculty of ChemistryInstitute of Organic ChemistryUniversity of ViennaWähringer Straße 381090ViennaAustria
- Christian-Doppler Laboratory for Entropy-Oriented Drug DesignJosef-Holaubek-Platz 21090ViennaAustria
| | - Nuno Maulide
- Faculty of ChemistryInstitute of Organic ChemistryUniversity of ViennaWähringer Straße 381090ViennaAustria
- Christian-Doppler Laboratory for Entropy-Oriented Drug DesignJosef-Holaubek-Platz 21090ViennaAustria
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Kanikarapu S, Gogoi MP, Dutta S, Sahoo AK. A 6- endo-dig Thiolative Cyclization of Yne-Ynamides: Access to Thiodihydropyridin-2-ones. Org Lett 2022; 24:8289-8294. [DOI: 10.1021/acs.orglett.2c03225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Suresh Kanikarapu
- School of Chemistry, University of Hyderabad, Hyderabad, India 500046
| | | | - Shubham Dutta
- School of Chemistry, University of Hyderabad, Hyderabad, India 500046
| | - Akhila K. Sahoo
- School of Chemistry, University of Hyderabad, Hyderabad, India 500046
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Wang H, Hu M, Wang XN, Chang J. Metal-free hydroalkoxylation of ynesulfonamides with alcohols. Org Biomol Chem 2022; 20:3408-3412. [PMID: 35380156 DOI: 10.1039/d2ob00420h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Efforts for developing a convenient and expeditious method for synthesizing alkoxy-substituted enamides via nucleophilic addition of alcohols to ynesulfonamides are described. This sequence is completely regioselective and highly stereoselective, and leads to the hydroalkoxylation products in high yields under mild reaction conditions.
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Affiliation(s)
- Hanhan Wang
- Collaborative Innovation Center of New Drug Research and Safety Evaluation, Henan Province, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, P. R. China.
| | - Mengjun Hu
- Collaborative Innovation Center of New Drug Research and Safety Evaluation, Henan Province, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, P. R. China.
| | - Xiao-Na Wang
- Collaborative Innovation Center of New Drug Research and Safety Evaluation, Henan Province, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, P. R. China.
| | - Junbiao Chang
- Collaborative Innovation Center of New Drug Research and Safety Evaluation, Henan Province, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, P. R. China.
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Iwabuchi Y, Nagasawa S. The Utility of Oxoammonium Species in Organic Synthesis: Beyond Alcohol Oxidation. HETEROCYCLES 2022. [DOI: 10.3987/rev-21-sr(r)2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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Heindl S, Riomet M, Matyasovsky J, Lemmerer M, Malzer N, Maulide N. Chemoselektive γ-Oxidation von β,γ-ungesättigten Amiden mit TEMPO. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 133:19271-19275. [PMID: 38505148 PMCID: PMC10946935 DOI: 10.1002/ange.202104023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 06/02/2021] [Indexed: 02/05/2023]
Abstract
AbstractEin chemoselektives und robustes Protokoll zur γ‐Oxidation von β,γ‐ungesättigten Amiden wird dargelegt. Bei dieser Methode ermöglicht elektrophile Amidaktivierung eine bei ungesättigten Amiden bisher selten angewendete regioselektive Reaktion mit TEMPO, die zu γ‐aminoxylierten α,β‐ungesättigten Amiden führt. Radikalische Zyklisierungen und Oxidationen der synthetisierten Produkte untermauern die Nützlichkeit der hergestellten Verbindungen.
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Affiliation(s)
- Sebastian Heindl
- Institut für Organische ChemieUniversität WienWähringer Straße 381090WienÖsterreich
| | - Margaux Riomet
- Institut für Organische ChemieUniversität WienWähringer Straße 381090WienÖsterreich
| | - Ján Matyasovsky
- Institut für Organische ChemieUniversität WienWähringer Straße 381090WienÖsterreich
| | - Miran Lemmerer
- Institut für Organische ChemieUniversität WienWähringer Straße 381090WienÖsterreich
| | - Nicolas Malzer
- Institut für Organische ChemieUniversität WienWähringer Straße 381090WienÖsterreich
| | - Nuno Maulide
- Institut für Organische ChemieUniversität WienWähringer Straße 381090WienÖsterreich
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Kumar R, Nguyen QH, Um TW, Shin S. Recent Progress in Enolonium Chemistry under Metal-Free Conditions. CHEM REC 2021; 22:e202100172. [PMID: 34418282 DOI: 10.1002/tcr.202100172] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/08/2021] [Accepted: 08/11/2021] [Indexed: 11/09/2022]
Abstract
Umpolung approach through inversion of the polarity of conventional enolates, has opened up an unprecedented opportunity in the cross-coupling via alkylation. The enolonium equivalents can be accessed either by hypervalent iodine reagents, activation/oxidation of amides, or the oxidation of alkynes. Under umpolung conditions, highly basic conditions required for classical enolate chemistry can be avoided, and they can couple with unmodified nucleophiles such as heteroatom donors and electron-rich arenes.
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Affiliation(s)
- Ravi Kumar
- Department of Chemistry, Center for New Directions in Organic Chemistry (CNOS), and Institute for Natural Sciences, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea
| | - Quynh H Nguyen
- Department of Chemistry, Center for New Directions in Organic Chemistry (CNOS), and Institute for Natural Sciences, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea
| | - Tae-Woong Um
- Department of Chemistry, Center for New Directions in Organic Chemistry (CNOS), and Institute for Natural Sciences, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea
| | - Seunghoon Shin
- Department of Chemistry, Center for New Directions in Organic Chemistry (CNOS), and Institute for Natural Sciences, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea
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Heindl S, Riomet M, Matyasovsky J, Lemmerer M, Malzer N, Maulide N. Chemoselective γ-Oxidation of β,γ-Unsaturated Amides with TEMPO. Angew Chem Int Ed Engl 2021; 60:19123-19127. [PMID: 34146371 PMCID: PMC8456850 DOI: 10.1002/anie.202104023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 06/02/2021] [Indexed: 12/23/2022]
Abstract
A chemoselective and robust protocol for the γ‐oxidation of β,γ‐unsaturated amides is reported. In this method, electrophilic amide activation, in a rare application to unsaturated amides, enables a regioselective reaction with TEMPO resulting in the title products. Radical cyclisation reactions and oxidation of the synthesised products highlight the synthetic utility of the products obtained.
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Affiliation(s)
- Sebastian Heindl
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Margaux Riomet
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Ján Matyasovsky
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Miran Lemmerer
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Nicolas Malzer
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Nuno Maulide
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
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10
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Wang DL, Jiang NQ, Cai ZJ, Ji SJ. Amidation-Ketonization-Selenation of Terminal Alkynes Using TEMPO and Elemental Selenium. J Org Chem 2021; 86:9898-9904. [PMID: 34165301 DOI: 10.1021/acs.joc.1c01066] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein, we present a novel silver- or copper-mediated direct amidation-ketonization-selenation of terminal alkynes for the synthesis of α-oxo-selenoamides. The reaction utilized easily accessible elemental selenium as the source of selenium. In addition, the 18O labeling experiment revealed that TEMPO is the oxygen source of the carbonyl group. The reaction takes advantage of an unsaturated C≡C bond to construct new C═O, C═Se, and C-N bonds in one step.
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Affiliation(s)
- Dian-Liang Wang
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, P. R. China
| | - Nan-Quan Jiang
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, P. R. China
| | - Zhong-Jian Cai
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, P. R. China
| | - Shun-Jun Ji
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, P. R. China
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11
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Sen' VD, Golubev VA, Shilov GV, Chernyak AV, Kurmaz VA, Luzhkov VB. Oxygen Atom Transfer in the Oxidation of Dimethyl Sulfoxide by Oxoammonium Cations. J Org Chem 2021; 86:3176-3185. [PMID: 33449678 DOI: 10.1021/acs.joc.0c02526] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cyclic oxoammonium salts and DMSO are known as important reagents for their diverse and unique reactivity. In the present work, we have studied the reaction of six- and five-membered oxoammonium salts with DMSO. The reaction includes ∼100% selective transfer of the O atom from the >N+═O group to the S atom of DMSO and structural rearrangement of the remaining cationic framework, leading to the formation of hydrolytically unstable iminium salts. The logarithms of the bimolecular rate constants k of the reaction correlated linearly with the reduction potentials E>N+═O/>N-O•, a relationship known for other electrophile-nucleophile combinations. The kinetic data and results of the DFT calculations allow for the suggestion that the studied process proceeds via the prereactive charge-transfer complex >N+═O···S (O)Me2 and its direct concerted rearrangement to the iminium salts. An alternative mechanism that includes intermediate steps with discrete nitrenium cations can be ruled out on the basis of product analysis and DFT computations. The obtained results allow a deeper understanding of the redox chemistry of a pair of nitroxide radicals-oxoammonium cations.
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Affiliation(s)
- Vasily D Sen'
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Russian Federation
| | - Valery A Golubev
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Russian Federation
| | - Gennadii V Shilov
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Russian Federation
| | - Alexander V Chernyak
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Russian Federation
| | - Vladimir A Kurmaz
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Russian Federation
| | - Victor B Luzhkov
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Russian Federation.,Department of Fundamental Physico-Chemical Engineering, Lomonosov Moscow State University, Moscow 119991, Russia Federation
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12
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Lynch CC, Sripada A, Wolf C. Asymmetric synthesis with ynamides: unique reaction control, chemical diversity and applications. Chem Soc Rev 2020; 49:8543-8583. [PMID: 33073285 PMCID: PMC8383824 DOI: 10.1039/d0cs00769b] [Citation(s) in RCA: 106] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ynamides are among the most powerful building blocks in organic synthesis and have become invaluable starting materials for the construction of multifunctional compounds and challenging architectures that would be difficult to prepare otherwise. The rapidly growing popularity originates from the unique reactivity and ease of manipulation of the polarized ynamide triple bond, the advance of practical methods for making them, and the simplicity of storage and handling. These attractive features and the demonstration of numerous synthetic applications have spurred the development of intriguing asymmetric reaction strategies during the last decade. An impressive variety of chemo-, regio- and stereoselective carbon-carbon and carbon-heteroatom bond forming reactions with ynamides have been developed and now significantly enrich the toolbox of synthetic chemists. This review provides a comprehensive overview of asymmetric ynamide chemistry since 2010 with a focus on the general scope, current limitations, stereochemical reaction control and mechanistic aspects.
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Affiliation(s)
- Ciarán C Lynch
- Department of Chemistry, Georgetown University, 37th and O Streets, Washington, DC 20057, USA.
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Moskowitz M, Wolf C. Catalytic Enantioselective Ynamide Additions to Isatins: Concise Access to Oxindole Alkaloids. Angew Chem Int Ed Engl 2019; 58:3402-3406. [PMID: 30695127 PMCID: PMC6444906 DOI: 10.1002/anie.201814074] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/28/2019] [Indexed: 11/05/2022]
Abstract
The highly enantioselective addition of terminal ynamides to a variety of isatins, catalyzed by a bisoxazolidine copper complex under mild, base-free reaction conditions, is described. The reaction is broad in scope, scalable, applicable to unprotected isatins, and provides efficient access to 3-hydroxyoxindoles carrying a tetrasubstituted chiral center with excellent yields and enantioselectivities. Synthetically versatile, multifunctional 3-hydroxyindolinones are obtained by hydration, partial hydrogenation, or hydroxyacyloxylation of the ynamide moiety at room temperature and exhaustive hydrogenation followed by reductive detosylation and spontaneous cyclization affords cinchonamidine alkaloids.
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Affiliation(s)
- Max Moskowitz
- Department of Chemistry, Georgetown University, 37 and O Streets, Washington, D.C. 20057 (USA)
| | - Christian Wolf
- Department of Chemistry, Georgetown University, 37 and O Streets, Washington, D.C. 20057 (USA)
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Moskowitz M, Wolf C. Catalytic Enantioselective Ynamide Additions to Isatins: Concise Access to Oxindole Alkaloids. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201814074] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Max Moskowitz
- Department of Chemistry; Georgetown University; 37 and O Streets Washington DC 20057 USA
| | - Christian Wolf
- Department of Chemistry; Georgetown University; 37 and O Streets Washington DC 20057 USA
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Affiliation(s)
- Dilip V. Patil
- Department of Chemistry; Center for New Directions in Organic Synthesis (CNOS); Institution for Natural Sciences; Hanyang University; 222 Wangsimni-ro Seongdong-gu Seoul Korea 14763
| | - Seunghoon Shin
- Department of Chemistry; Center for New Directions in Organic Synthesis (CNOS); Institution for Natural Sciences; Hanyang University; 222 Wangsimni-ro Seongdong-gu Seoul Korea 14763
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16
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Brutiu BR, Bubeneck WA, Cvetkovic O, Li J, Maulide N. On the formation of seven-membered rings by arene-ynamide cyclization. MONATSHEFTE FUR CHEMIE 2018; 150:3-10. [PMID: 30662090 PMCID: PMC6320749 DOI: 10.1007/s00706-018-2320-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 10/10/2018] [Indexed: 12/31/2022]
Abstract
ABSTRACT A Brønsted acid-catalyzed selective arene-ynamide cyclization is described. This reaction proceeds via a keteniminium intermediate and enables the preparation of seven-membered ring enamide products. Mechanistic studies uncover an unusual product inhibition behavior. GRAPHICAL ABSTRACT
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Affiliation(s)
- Bogdan R. Brutiu
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Wilhelm Andrei Bubeneck
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Olivera Cvetkovic
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Jing Li
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Nuno Maulide
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
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Stoyanovsky AD, Stoyanovsky DA. 1-Oxo-2,2,6,6-tetramethylpiperidinium bromide converts α-H N,N-dialkylhydroxylamines to nitrones via a two-electron oxidation mechanism. Sci Rep 2018; 8:15323. [PMID: 30333514 PMCID: PMC6193029 DOI: 10.1038/s41598-018-33639-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 10/02/2018] [Indexed: 01/13/2023] Open
Abstract
Herein we provide experimental proof that 1-oxo-2,2,6,6-tetramethylpiperidinium bromide converts α-H N,N-dialkylhydroxylamines to nitrones via a two-electron oxidation mechanism. The reactions reported are rapid, proceed under mild conditions, and afford nitrones in excellent yields.
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Affiliation(s)
| | - Detcho A Stoyanovsky
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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Sanz-Marco A, Martinez-Erro S, Martín-Matute B. Selective Synthesis of Unsymmetrical Aliphatic Acyloins through Oxidation of Iridium Enolates. Chemistry 2018; 24:11564-11567. [PMID: 29928782 DOI: 10.1002/chem.201803117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Indexed: 11/09/2022]
Abstract
The first method to access unsymmetrical aliphatic acyloins is presented. The method relies on a fast 1,3-hydride shift mediated by an IrIII complex in allylic alcohols followed by oxidation with TEMPO+ . The direct conversion of allylic alcohols into acyloins is achieved in a one-pot procedure. Further functionalization of the Cα' of the α-amino-oxylated ketone products gives access to highly functionalized unsymmetrical aliphatic ketones, which further highlights the utility of this transformation.
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Affiliation(s)
- Amparo Sanz-Marco
- Department of Organic Chemistry, Stockholm University, Stockholm, 10691, Sweden
| | | | - Belén Martín-Matute
- Department of Organic Chemistry, Stockholm University, Stockholm, 10691, Sweden
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Pinto A, Kaiser D, Maryasin B, Di Mauro G, González L, Maulide N. Hydrative Aminoxylation of Ynamides: One Reaction, Two Mechanisms. Chemistry 2018; 24:2515-2519. [PMID: 29293283 PMCID: PMC5838720 DOI: 10.1002/chem.201706063] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Indexed: 11/08/2022]
Abstract
Organic synthesis boasts a wide array of reactions involving either radical species or ionic intermediates. The combination of radical and polar species, however, has not been explored to a comparable extent. Herein we present the hydrative aminoxylation of ynamides, a reaction which can proceed by either a polar-radical crossover mechanism or through a rare cationic activation. Common to both processes is the versatility of the persistent radical TEMPO and its oxidised oxoammonium derivative TEMPO+ . The unique mechanisms of these processes are elucidated experimentally and by in-depth DFT-calculations.
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Affiliation(s)
- Alexandre Pinto
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Daniel Kaiser
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Boris Maryasin
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria.,Institute of Theoretical Chemistry, University of Vienna, Währinger Strasse 17, 1090, Vienna, Austria
| | - Giovanni Di Mauro
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Leticia González
- Institute of Theoretical Chemistry, University of Vienna, Währinger Strasse 17, 1090, Vienna, Austria
| | - Nuno Maulide
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
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20
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Habert L, Retailleau P, Gillaizeau I. Rapid synthesis of 3-amino isocoumarin derivatives from ynamides. Org Biomol Chem 2018; 16:7351-7355. [DOI: 10.1039/c8ob02305k] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A novel and efficient fast synthesis of 3-amino isocoumarins in good to excellent yields is reported.
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Affiliation(s)
- Loïc Habert
- Institute of Organic and Analytical Chemistry
- ICOA UMR 7311 CNRS
- Université d'Orléans
- Pôle de chimie
- 45100 Orléans
| | - Pascal Retailleau
- Institut de Chimie des Substances Naturelles
- CNRS
- 91198 Gif-sur-Yvette Cedex
- France
| | - Isabelle Gillaizeau
- Institute of Organic and Analytical Chemistry
- ICOA UMR 7311 CNRS
- Université d'Orléans
- Pôle de chimie
- 45100 Orléans
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