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Zhao X, Hou YL, Qian BC, Shen GB. Thermodynamic H-Abstraction Abilities of Nitrogen Centered Radical Cations as Potential Hydrogen Atom Transfer Catalysts in Y-H Bond Functionalization. ACS OMEGA 2024; 9:26708-26718. [PMID: 38911737 PMCID: PMC11191127 DOI: 10.1021/acsomega.4c04209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 05/20/2024] [Accepted: 05/23/2024] [Indexed: 06/25/2024]
Abstract
Y-H bond functionalization has always been the focus of research interest in the area of organic synthesis. Direct hydrogen atom transfer (HAT) from the Y-H bond is one of the most efficient and practical methods to activate the Y-H bond. Recently, nitrogen centered radical cations were broadly utilized as H-abstraction catalysts to activate Y-H bonds via the HAT process. As a type of HAT catalyst, the H-affinity of nitrogen centered radical cations is a significant thermodynamic parameter to quantitatively evaluate the thermodynamic H-abstraction potentials of nitrogen centered radical cations. In this work, the pK a values of 120 protonated N-containing compounds in acetonitrile (AN) are predicted, and the H-affinities of 120 nitrogen centered radical cations in AN are derived from the reduction potentials of nitrogen centered radical cations and pK a of protonated N-containing compounds using Hess' law. This work focuses on the H-abstraction abilities of 120 nitrogen centered radical cations in AN to enrich the molecule library of novel HAT catalysts or H-abstractors and provides valuable thermodynamic guidelines for the application of nitrogen centered radical cations in Y-H bond functionalization.
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Affiliation(s)
- Xia Zhao
- College of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Yi-Lin Hou
- College of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Bao-Chen Qian
- College of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Guang-Bin Shen
- College of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
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2
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van der Zee LJC, Hofman J, van Gaalen JM, Slootweg JC. Mechanistic studies on single-electron transfer in frustrated Lewis pairs and its application to main-group chemistry. Chem Soc Rev 2024; 53:4862-4876. [PMID: 38623621 PMCID: PMC11104263 DOI: 10.1039/d4cs00185k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Indexed: 04/17/2024]
Abstract
Advances in the field of frustrated Lewis pair (FLP) chemistry have led to the discovery of radical pairs, obtained by a single-electron transfer (SET) from the Lewis base to the Lewis acid. Radical pairs are intriguing for their potential to enable cooperative activation of challenging substrates (e.g., CH4, N2) in a homolytic fashion, as well as the exploration of novel radical reactions. In this review, we will cover the two known mechanisms of SET in FLPs-thermal and photoinduced-along with methods (i.e., CV, DFT, UV-vis) to predict the mechanism and to characterise the involved electron donors and acceptors. Furthermore, the available techniques (i.e., EPR, UV-vis, transient absorption spectroscopy) for studying the corresponding radical pairs will be discussed. Initially, two model systems (PMes3/CPh3+ and PMes3/B(C6F5)3) will be reviewed to highlight the difference between a thermal and a photoinduced SET mechanism. Additionally, three cases are analysed to provide further tools and insights into characterizing electron donors and acceptors, and the associated radical pairs. Firstly, a thermal SET process between LiHMDS and [TEMPO][BF4] is discussed. Next, the influence of Lewis acid complexation on the electron acceptor will be highlighted to facilitate a SET between (pBrPh)3N and TCNQ. Finally, an analysis of sulfonium salts as electron acceptors will demonstrate how to manage systems with rapidly decomposing radical species. This framework equips the reader with an expanded array of tools for both predicting and characterizing SET events within FLP chemistry, thereby enabling its extension and application to the broader domain of main-group (photo)redox chemistry.
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Affiliation(s)
- Lars J C van der Zee
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090 GD Amsterdam, The Netherlands.
| | - Jelle Hofman
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090 GD Amsterdam, The Netherlands.
| | - Joost M van Gaalen
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090 GD Amsterdam, The Netherlands.
| | - J Chris Slootweg
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090 GD Amsterdam, The Netherlands.
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3
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Ren J, Ding SH, Li XN, Zhao QS. Unified Strategy Enables the Collective Syntheses of Structurally Diverse Indole Alkaloids. J Am Chem Soc 2024; 146:7616-7627. [PMID: 38446772 DOI: 10.1021/jacs.3c13869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Natural products and their analogues are significant sources of therapeutic lead compounds. However, synthetic strategies for generating large collections of these molecules remain a significant challenge. The most difficult step in their synthesis is the design of a common intermediate that can be easily transformed into natural products belonging to different families. This study demonstrates the evolution of synthetic tactics designed to assemble the functionalized piperidines present in indole alkaloids from a common intermediate. More importantly, we also report a previously unknown Ir- and Er-catalyzed dehydrogenative spirocyclization reaction that enables direct access to spirocyclic oxindole alkaloids. As a practical application, the asymmetric total syntheses of 29 natural alkaloids belonging to different families were accomplished by following a uniform synthetic route. The proposed methodology extends the capability of the iridium-catalyzed dehydrogenative coupling reaction to the realm of indole-alkaloid synthesis and provides new opportunities for the efficient preparation of natural product-like molecules.
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Affiliation(s)
- Jian Ren
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Shi-Hua Ding
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Xiao-Nian Li
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Qin-Shi Zhao
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
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4
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Majhi J, Molander GA. Recent Discovery, Development, and Synthetic Applications of Formic Acid Salts in Photochemistry. Angew Chem Int Ed Engl 2024; 63:e202311853. [PMID: 37812639 DOI: 10.1002/anie.202311853] [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: 08/14/2023] [Revised: 10/05/2023] [Accepted: 10/09/2023] [Indexed: 10/11/2023]
Abstract
The advancement of sustainable photoredox catalysis in synthetic organic chemistry has evolved immensely because of the development of versatile and cost-effective reagents. In recent years, a substantial effort has been dedicated to exploring the utility of formic acid salts in various photochemical reactions. In this context, formates have demonstrated diverse capabilities, functioning as reductants, sources of carbonyl groups, and reagents for hydrogen atom transfer. Notably, the CO2 ⋅- radical anion derived from formate exhibits strong reductant properties for cleaving both C-X and C-O bonds. Moreover, these salts play a pivotal role in carboxylation reactions, further highlighting their significance in a variety of photochemical transformations. The ability of formates to serve as reductants, carbonyl sources, and hydrogen atom transfer reagents reveal exciting possibilities in synthetic organic chemistry. This minireview highlights an array of captivating discoveries, underscoring the crucial role of formates in diverse and distinctive photochemical methods, enabling access to a wide range of value-added compounds.
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Affiliation(s)
- Jadab Majhi
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Gary A Molander
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
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5
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Ghosh SK, He L, Tang Z, Comito RJ. Selective and Functional-Group-Tolerant Photoalkylation of Imines by Energy-Transfer Photocatalysis. J Org Chem 2023; 88:15209-15217. [PMID: 37875007 DOI: 10.1021/acs.joc.3c01722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Basic amines show broad bioactivity and remain a promising source of new medicines. The direct photoalkylation of imines offers a promising strategy for complex amines. However, the lack of efficient imine photoreactivity hinders this reaction and remains a fundamental limitation in organic photochemistry. We report an efficient photoalkylation of imines that provides primary amines directly without protecting or leaving groups. The transformation effects C-H addition across N-H imines under energy-transfer photocatalysis by a ketone. Our method is distinguished from organometallic, metal-catalyzed, and photoredox approaches to imine alkylation by its lack of protecting groups and its broad scope, which includes unactivated alkanes, protic substrates, basic amines, heterocycles, and ketone imines. We highlight this scope through the condensation and alkylation of two pharmaceutical ketones, providing complex amines succinctly. Our mechanistic analysis supports a three-step process, involving hydrogen-atom transfer to an imine triplet excited state, intersystem crossing, and radical recombination, with photocatalytic enhancement through energy transfer. We further show that N-H imines are more photoreactive than N-substituted imines, a distinction partially explained by sterics and side reactions. To fully explain this distinction, we introduce the thermodynamic parameter excited-state hydrogen-atom affinity, which is highly effective at predicting the photoreactivity of imines.
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Affiliation(s)
- Subrata K Ghosh
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| | - Lizhe He
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| | - Zilu Tang
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| | - Robert J Comito
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
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6
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Meger FS, Murphy JA. Recent Advances in C-H Functionalisation through Indirect Hydrogen Atom Transfer. Molecules 2023; 28:6127. [PMID: 37630379 PMCID: PMC10459052 DOI: 10.3390/molecules28166127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/09/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
The functionalisation of C-H bonds has been an enormous achievement in synthetic methodology, enabling new retrosynthetic disconnections and affording simple synthetic equivalents for synthons. Hydrogen atom transfer (HAT) is a key method for forming alkyl radicals from C-H substrates. Classic reactions, including the Barton nitrite ester reaction and Hofmann-Löffler-Freytag reaction, among others, provided early examples of HAT. However, recent developments in photoredox catalysis and electrochemistry have made HAT a powerful synthetic tool capable of introducing a wide range of functional groups into C-H bonds. Moreover, greater mechanistic insights into HAT have stimulated the development of increasingly site-selective protocols. Site-selectivity can be achieved through the tuning of electron density at certain C-H bonds using additives, a judicious choice of HAT reagent, and a solvent system. Herein, we describe the latest methods for functionalizing C-H/Si-H/Ge-H bonds using indirect HAT between 2018-2023, as well as a critical discussion of new HAT reagents, mechanistic aspects, substrate scopes, and background contexts of the protocols.
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Affiliation(s)
- Filip S. Meger
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, 16 Avinguda dels Països Catalans, 43007 Tarragona, Catalonia, Spain
| | - John A. Murphy
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK
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7
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Lepori M, Schmid S, Barham JP. Photoredox catalysis harvesting multiple photon or electrochemical energies. Beilstein J Org Chem 2023; 19:1055-1145. [PMID: 37533877 PMCID: PMC10390843 DOI: 10.3762/bjoc.19.81] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 07/07/2023] [Indexed: 08/04/2023] Open
Abstract
Photoredox catalysis (PRC) is a cutting-edge frontier for single electron-transfer (SET) reactions, enabling the generation of reactive intermediates for both oxidative and reductive processes via photon activation of a catalyst. Although this represents a significant step towards chemoselective and, more generally, sustainable chemistry, its efficacy is limited by the energy of visible light photons. Nowadays, excellent alternative conditions are available to overcome these limitations, harvesting two different but correlated concepts: the use of multi-photon processes such as consecutive photoinduced electron transfer (conPET) and the combination of photo- and electrochemistry in synthetic photoelectrochemistry (PEC). Herein, we review the most recent contributions to these fields in both oxidative and reductive activations of organic functional groups. New opportunities for organic chemists are captured, such as selective reactions employing super-oxidants and super-reductants to engage unactivated chemical feedstocks, and scalability up to gram scales in continuous flow. This review provides comparisons between the two techniques (multi-photon photoredox catalysis and PEC) to help the reader to fully understand their similarities, differences and potential applications and to therefore choose which method is the most appropriate for a given reaction, scale and purpose of a project.
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Affiliation(s)
- Mattia Lepori
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitatsstraße 31, 93040 Regensburg, Germany
| | - Simon Schmid
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitatsstraße 31, 93040 Regensburg, Germany
| | - Joshua P Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitatsstraße 31, 93040 Regensburg, Germany
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8
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Miyajima R, Ooe Y, Miura T, Ikoma T, Iwamoto H, Takizawa SY, Hasegawa E. Triarylamine-Substituted Benzimidazoliums as Electron Donor-Acceptor Dyad-Type Photocatalysts for Reductive Organic Transformations. J Am Chem Soc 2023; 145:10236-10248. [PMID: 37127911 DOI: 10.1021/jacs.3c01264] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Triarylamine-substituted benzimidazoliums (BI+-PhNAr2), new electron donor-acceptor dyad molecules, were synthesized. Their photocatalytic properties for reductive organic transformations were explored using absorption and fluorescence spectroscopy, redox potential determinations, density functional theory calculations, transient absorption spectroscopy, and reduction reactions of selected substrates. The results show that irradiation of BI+-PhNAr2 promotes photoinduced intramolecular electron transfer to form a long-lived (∼300 μs) charge shifted state (BI•-PhN•+Ar2). In the pathway for photocatalysis of reduction reactions of substrates, BI•-PhN•+Ar2 is subsequently transformed to the neutral benzimidazolyl radical (BI•-PhNAr2) by single-electron transfer from the donor 1,3-dimethyl-2-phenylbenzimidazoline (BIH-Ph) serving as a cooperative agent. Among the benzimidazoliums explored, the bromo-substituted analogue BI+-PhN(C6H4Br-p)2 in conjunction with BIH-Ph demonstrates the most consistent catalytic performance.
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Affiliation(s)
- Ryo Miyajima
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Yuuki Ooe
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Tomoaki Miura
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Tadaaki Ikoma
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Hajime Iwamoto
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Shin-Ya Takizawa
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Eietsu Hasegawa
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
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9
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Hidasová D, Slanina T. Triarylamminium Radical Cation Facilitates the Deprotection of tert-Butyl Groups in Esters, Ethers, Carbonates, and Carbamates. J Org Chem 2023. [PMID: 37126731 DOI: 10.1021/acs.joc.3c00238] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We report a catalytic protocol for mild OtBu deprotection using two commercial reagents: the tris-4-bromophenylamminium radical cation, commonly known as magic blue (MB•+), and triethylsilane. Magic blue catalytically facilitates the cleavage of the C-O bond in tert-butyl carbamates, carbonates, esters, and ethers in a high isolated yield of up to 95%, and sacrificial triethylsilane accelerates the reaction. Without requiring high temperatures, transition metals, or strong acidic or basic catalysts, this method is suitable for structurally diverse compounds, including aliphatic, aromatic, and heterocyclic substrates.
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Affiliation(s)
- Denisa Hidasová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague, Czech Republic
| | - Tomáš Slanina
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague, Czech Republic
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10
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Kumar A, Malevich P, Mewes L, Wu S, Barham JP, Hauer J. Transient absorption spectroscopy based on uncompressed hollow core fiber white light proves pre-association between a radical ion photocatalyst and substrate. J Chem Phys 2023; 158:144201. [PMID: 37061463 DOI: 10.1063/5.0142225] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
We present a hollow-core fiber (HCF) based transient absorption experiment, with capabilities beyond common titanium:sapphire based setups. By spectral filtering of the HCF spectrum, we provide pump pulses centered at 425 nm with several hundred nJ of pulse energy at the sample position. By employing the red edge of the HCF output for seeding CaF2, we obtain smooth probing spectra in the range between 320 and 900 nm. We demonstrate the capabilities of our experiment by following the ultrafast relaxation dynamics of a radical cationic photocatalyst to prove its pre-association with an arene substrate, a phenomenon that was not detectable previously by steady-state spectroscopic techniques. The detected preassembly rationalizes the successful participation of radical ionic photocatalysts in single electron transfer reactions, a notion that has been subject to controversy in recent years.
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Affiliation(s)
- Ajeet Kumar
- Department of Chemistry and Catalysis Research Center (CRC), School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany
| | - Pavel Malevich
- Department of Chemistry and Catalysis Research Center (CRC), School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany
| | - Lars Mewes
- Department of Chemistry and Catalysis Research Center (CRC), School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany
| | - Shangze Wu
- Universität Regensburg, Fakultät für Chemie und Pharmazie, 93040 Regensburg, Germany
| | - Joshua P Barham
- Universität Regensburg, Fakultät für Chemie und Pharmazie, 93040 Regensburg, Germany
| | - Jürgen Hauer
- Department of Chemistry and Catalysis Research Center (CRC), School of Natural Sciences, Technical University of Munich, 85748 Garching, Germany
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11
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Lai Q, Chen S, Zou L, Lin C, Huang S, Fu L, Cai L, Cai S. Syntheses of functionalized benzocoumarins by photoredox catalysis. Org Biomol Chem 2023; 21:1181-1186. [PMID: 36632780 DOI: 10.1039/d2ob02225g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Direct functionalization of inert C(sp3)-H bonds is an attractive synthetic technology for the preparation of pharmaceutically significant compounds in modern synthetic organic chemistry. In this work, we report a new method for the synthesis of functionalized benzocoumarins through the strategy of activation of multiple C-H bonds on 2-aryl toluenes under visible-light-enabled photoredox conditions. This method has the advantages of high functional group compatibility, mild reaction conditions, and effectively avoiding the use of strong oxidants and precious metal catalysts. Detailed mechanistic investigations, including spectroscopic and electrochemical studies, support the reaction's mechanistic course.
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Affiliation(s)
- Qihong Lai
- Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, School of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou, 363000, China.
| | - Shanyi Chen
- Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, School of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou, 363000, China.
| | - Linnan Zou
- Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, School of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou, 363000, China.
| | - Chengzhi Lin
- Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, School of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou, 363000, China.
| | - Shuling Huang
- Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, School of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou, 363000, China.
| | - Lailing Fu
- Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, School of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou, 363000, China.
| | - Lina Cai
- Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, School of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou, 363000, China.
| | - Shunyou Cai
- Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, School of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou, 363000, China. .,Guangdong Provincial Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
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12
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Maldonado-Domínguez M, Srnec M. Quantifiable polarity match effect on C-H bond cleavage reactivity and its limits in reaction design. Dalton Trans 2023; 52:1399-1412. [PMID: 36644790 DOI: 10.1039/d2dt04018b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
When oxidants favour cleaving a strong C-H bond at the expense of weaker ones, which are otherwise inherently preferred due to their favourable reaction energy, reactivity factors such as the polarity match effect are often invoked. Polarity match follows the intuition of electrophilic (nucleophilic) oxidants reacting faster with nucleophilic (electrophilic) C-H bonds. Nevertheless, this concept is purely qualitative and is best suited for a posteriori rationalization of experimental observations. Here, we propose and inspect two methods to quantify polar effects in C-H cleavage reactions, one by computation via the difference of atomic charges (Δq) of reacting atoms, and one amenable to experimental measurement through asynchronicity factors, η. By their application to three case studies, we observe that both Δq and η faithfully capture the notion of polarity match. The polarity match model, however, proves insufficient as a predictor of H-atom abstraction reactivity and we discourage its use as a standalone variable in reaction design. Besides this caveat, η and Δq (through its mapping on η) allow the implementation of polarity match into a Marcus-type model of reactivity, alleviating its shortcomings and making reaction planning feasible.
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Affiliation(s)
- Mauricio Maldonado-Domínguez
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, Prague 8, 18223, Czech Republic.
| | - Martin Srnec
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, Prague 8, 18223, Czech Republic.
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13
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Yakubov S, Stockerl WJ, Tian X, Shahin A, Mandigma MJP, Gschwind RM, Barham JP. Benzoates as photosensitization catalysts and auxiliaries in efficient, practical, light-powered direct C(sp 3)-H fluorinations. Chem Sci 2022; 13:14041-14051. [PMID: 36540818 PMCID: PMC9728569 DOI: 10.1039/d2sc05735b] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 10/28/2022] [Indexed: 12/14/2023] Open
Abstract
Of the methods for direct fluorination of unactivated C(sp3)-H bonds, photosensitization of SelectFluor is a promising approach. Although many substrates can be activated with photosensitizing catalysts, issues remain that hamper fluorination of complex molecules. Alcohol- or amine-containing functional groups are not tolerated, fluorination regioselectivity follows factors endogenous to the substrate and cannot be influenced by the catalyst, and reactions are highly air-sensitive. We report that benzoyl groups serve as highly efficient photosensitizers which, in combination with SelectFluor, enable visible light-powered direct fluorination of unactivated C(sp3)-H bonds. Compared to previous photosensitizer architectures, the benzoyls have versatility to function both (i) as a photosensitizing catalyst for simple substrate fluorinations and (ii) as photosensitizing auxiliaries for complex molecule fluorinations that are easily installed and removed without compromising yield. Our auxiliary approach (i) substantially decreases the reaction's induction period, (ii) enables C(sp3)-H fluorination of many substrates that fail under catalytic conditions, (iii) increases kinetic reproducibility, and (iv) promotes reactions to higher yields, in shorter times, on multigram scales, and even under air. Observations and mechanistic studies suggest an intimate 'assembly' of auxiliary and SelectFluor prior/after photoexcitation. The auxiliary allows other EnT photochemistry under air. Examples show how auxiliary placement proximally directs regioselectivity, where previous methods are substrate-directed.
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Affiliation(s)
- Shahboz Yakubov
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Willibald J Stockerl
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Xianhai Tian
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Ahmed Shahin
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
- Chemistry Department, Faculty of Science, Benha University 13518 Benha Egypt
| | - Mark John P Mandigma
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Ruth M Gschwind
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Joshua P Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
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14
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Ding H, Zhang S, Sun Z, Ma Q, Li Y, Yuan Y, Jia X. Tris(4-bromophenyl)aminium Hexachloroantimonate as a "Waste-Utilized"-Type Initiator-Promoted C-H Chlorination via C-H Activation Relay: Synthesis of Chlorinated Pyrroles. J Org Chem 2022; 87:15139-15151. [PMID: 36398528 DOI: 10.1021/acs.joc.2c01641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Using tris(4-bromophenyl)aminium hexachloroantimonate as a "waste-utilized"-type initiator, the aerobic oxidation of the sp3 C-H bond of proline esters was realized via C-H activation relay, giving a series of halogenated pyrroles in high yields. The mechanistic study revealed that the counterion, SbCl6-, was involved in the radical chlorination process, which provides a new way to understand the role of the counterions.
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Affiliation(s)
- Han Ding
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
| | - Shuwei Zhang
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
| | - Zheng Sun
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
| | - Qiyuan Ma
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
| | - Yuemei Li
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
| | - Yu Yuan
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
| | - Xiaodong Jia
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
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15
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Maldonado-Domínguez M, Srnec M. H-Atom Abstraction Reactivity through the Lens of Asynchronicity and Frustration with Their Counteracting Effects on Barriers. Inorg Chem 2022; 61:18811-18822. [DOI: 10.1021/acs.inorgchem.2c03269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Mauricio Maldonado-Domínguez
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, Prague 8 18223, Czech Republic
| | - Martin Srnec
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, Prague 8 18223, Czech Republic
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16
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Dimitrova D, McMahon C, Kennedy AR, Parkinson JA, Leach SG, Boulton LT, Pascoe DD, Murphy JA. A study of the reactivity of cyclic aminomethylammonium mannich salts. Tetrahedron 2022. [DOI: 10.1016/j.tet.2022.133120] [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]
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17
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Enders P, Májek M, Lam CM, Little D, Francke R. How to Harness Electrochemical Mediators for Photocatalysis – A Systematic Approach Using the Phenanthro[9,10‐d]imidazole Framework as a Test Case. ChemCatChem 2022. [DOI: 10.1002/cctc.202200830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Patrick Enders
- Leibniz Institute for Catalysis: Leibniz-Institut fur Katalyse eV Electrochemistry & Catalysis GERMANY
| | - Michal Májek
- Comenius University in Bratislava: Univerzita Komenskeho v Bratislave Institute of Chemistry SLOVAKIA
| | - Chiu Marco Lam
- University of California Santa Barbara Chemistry & Biochemistry UNITED STATES
| | - Daniel Little
- University of California Santa Barbara Chemistry & Biochemistry UNITED STATES
| | - Robert Francke
- Rostock University Institute of Chemistry Albert-Einstein-Str. 3a 18059 Rostock GERMANY
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18
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Oxidative lactonization of C(sp3)-H bond in methyl aromatic alcohols enabled by proton-coupled electron transfer. Sci China Chem 2022. [DOI: 10.1007/s11426-022-1283-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Barham JP, Kaur J. Site-Selective C(sp3)–H Functionalizations Mediated by Hydrogen Atom Transfer Reactions via α-Amino/α-Amido Radicals. SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/a-1677-6619] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
AbstractAmines and amides, as N-containing compounds, are ubiquitous in pharmaceutically-active scaffolds, natural products, agrochemicals, and peptides. Amides in nature bear a key responsibility for imparting three-dimensional structure, such as in proteins. Structural modifications to amines and amides, especially at their positions α to N, bring about profound changes in biological activity oftentimes leading to more desirable pharmacological profiles of small drug molecules. A number of recent developments in synthetic methodology for the functionalizations of amines and amides omit the need of their directing groups or pre-functionalizations, achieving direct activation of the otherwise relatively benign C(sp3)–H bonds α to N. Among these, hydrogen atom transfer (HAT) has proven a very powerful platform for the selective activation of amines and amides to their α-amino and α-amido radicals, which can then be employed to furnish C–C and C–X (X = heteroatom) bonds. The abilities to both form these radicals and control their reactivity in a site-selective manner is of utmost importance for such chemistries to witness applications in late-stage functionalization. Therefore, this review captures contemporary HAT strategies to realize chemo- and regioselective amine and amide α-C(sp3)–H functionalization, based on bond strengths, bond polarities, reversible HAT equilibria, traceless electrostatic-directing auxiliaries, and steric effects of in situ-generated HAT agents.1 Introduction2 Functionalizations of Amines3 Functionalizations of Carbamates4 Functionalizations of Amides5 Conclusion
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20
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Wu S, Kaur J, Karl TA, Tian X, Barham JP. Synthetische molekulare Photoelektrochemie: neue synthetische Anwendungen, mechanistische Einblicke und Möglichkeiten zur Skalierung. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202107811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Shangze Wu
- Universität Regensburg Fakultät für Chemie und Pharmazie 93040 Regensburg Deutschland
| | - Jaspreet Kaur
- Universität Regensburg Fakultät für Chemie und Pharmazie 93040 Regensburg Deutschland
| | - Tobias A. Karl
- Universität Regensburg Fakultät für Chemie und Pharmazie 93040 Regensburg Deutschland
| | - Xianhai Tian
- Universität Regensburg Fakultät für Chemie und Pharmazie 93040 Regensburg Deutschland
| | - Joshua P. Barham
- Universität Regensburg Fakultät für Chemie und Pharmazie 93040 Regensburg Deutschland
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21
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Zhang J, Paladugu SR, Gillard RM, Sarkar A, Boger DL. Tris(4-bromophenyl)aminium Hexachloroantimonate-Mediated Intermolecular C(sp 2)-C(sp 3) Free Radical Coupling of Vindoline with β-Ketoesters and Related Compounds. J Am Chem Soc 2022; 144:495-502. [PMID: 34963278 PMCID: PMC8758398 DOI: 10.1021/jacs.1c10971] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A powerful tris(4-bromophenyl)aminium hexachloroantimonate (BAHA) mediated regioselective intermolecular coupling reaction of vindoline with a wide range of substrates that include β-ketoesters, β-diketones, β-ketoaldehydes, β-ketonitriles, β-ketolactones, β-ketolactams, β-cyanoesters, and malononitriles is detailed. The BAHA-promoted intermolecular sp3/sp2 coupling, representing a special class of selective C-H functionalization reactions with direct carbon-carbon bond formation, proceeds with generation of a quaternary center bound to the aryl C15 center of vindoline capable of accommodating of the vinblastine C16' methyl ester and functionalized for subsequent divergent heterocycle introduction. A comprehensive examination of the reaction scope, optimization of subtle reaction parameters, and key insights into the reaction mechanism are described. Contrary to what might be prevailing expectations, studies suggest the plausible mechanism entails initial single-electron oxidation of the substrate enolate, not vindoline, and subsequent regiospecific addition of the resulting electrophilic radical to vindoline. As such and beyond the new arylation reaction with vindoline, the studies define a host of new, previously unrecognized, applications of BAHA and related triarylaminium radical cations that arises from their ability to generate stabilized electrophilic radicals from β-ketoesters and related substrates under nonreducing and metal-free conditions. Those exemplified herein include mediating stabilized enolate free radical arylation, dimerization, allylation, alkene addition, and α-oxidation reactions.
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Affiliation(s)
| | | | - Rachel M. Gillard
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA
| | - Anindya Sarkar
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA
| | - Dale L. Boger
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA
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22
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Maia da Silva Santos B, Dos Santos Dupim M, Paula de Souza C, Messias Cardozo T, Gadini Finelli F. DABCO-promoted photocatalytic C-H functionalization of aldehydes. Beilstein J Org Chem 2022; 17:2959-2967. [PMID: 35003372 PMCID: PMC8712972 DOI: 10.3762/bjoc.17.205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/07/2021] [Indexed: 11/29/2022] Open
Abstract
Herein we present a direct application of DABCO, an inexpensive and broadly accessible organic base, as a hydrogen atom transfer (HAT) abstractor in a photocatalytic strategy for aldehyde C–H activation. The acyl radicals generated in this step were arylated with aryl bromides through a well stablished nickel cross-coupling methodology, leading to a variety of interesting aryl ketones in good yields. We also performed computational calculations to shine light in the HAT step energetics and determined an optimized geometry for the transition state, showing that the hydrogen atom transfer between aldehydes and DABCO is a mildly endergonic, yet sufficiently fast step. The same calculations were performed with quinuclidine, for comparison of both catalysts and the differences are discussed.
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Affiliation(s)
- Bruno Maia da Silva Santos
- Instituto de Pesquisas de Produtos Naturais, Universidade Federal do Rio de Janeiro, 373, Carlos Chagas Ave, Rio de Janeiro RJ, 21941-902, Brazil
| | - Mariana Dos Santos Dupim
- Instituto de Pesquisas de Produtos Naturais, Universidade Federal do Rio de Janeiro, 373, Carlos Chagas Ave, Rio de Janeiro RJ, 21941-902, Brazil
| | - Cauê Paula de Souza
- Instituto de Química, Universidade Federal do Rio de Janeiro 149, Athos da Silveira Ramos Ave, Rio de Janeiro RJ, 21941-909, Brazil
| | - Thiago Messias Cardozo
- Instituto de Química, Universidade Federal do Rio de Janeiro 149, Athos da Silveira Ramos Ave, Rio de Janeiro RJ, 21941-909, Brazil
| | - Fernanda Gadini Finelli
- Instituto de Pesquisas de Produtos Naturais, Universidade Federal do Rio de Janeiro, 373, Carlos Chagas Ave, Rio de Janeiro RJ, 21941-902, Brazil
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23
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Mandigma MJP, Žurauskas J, MacGregor CI, Edwards LJ, Shahin A, d'Heureuse L, Yip P, Birch DJS, Gruber T, Heilmann J, John MP, Barham JP. An organophotocatalytic late-stage N–CH3 oxidation of trialkylamines to N-formamides with O2 in continuous flow. Chem Sci 2022; 13:1912-1924. [PMID: 35308839 PMCID: PMC8849051 DOI: 10.1039/d1sc05840a] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/26/2021] [Indexed: 12/25/2022] Open
Abstract
We report an organophotocatalytic, N–CH3-selective oxidation of trialkylamines in continuous flow. Based on the 9,10-dicyanoanthracene (DCA) core, a new catalyst (DCAS) was designed with solubilizing groups for flow processing. This allowed O2 to be harnessed as a sustainable oxidant for late-stage photocatalytic N–CH3 oxidations of complex natural products and active pharmaceutical ingredients bearing functional groups not tolerated by previous methods. The organophotocatalytic gas–liquid flow process affords cleaner reactions than in batch mode, in short residence times of 13.5 min and productivities of up to 0.65 g per day. Spectroscopic and computational mechanistic studies showed that catalyst derivatization not only enhanced solubility of the new catalyst compared to poorly-soluble DCA, but profoundly diverted the photocatalytic mechanism from singlet electron transfer (SET) reductive quenching with amines toward energy transfer (EnT) with O2. An N–CH3-selective trialkylamine oxidation to N-formamides is reported in continuous flow using gaseous O2. A novel, enhanced-solubility dicyanoanthracene organophotocatalyst switched the photochemical mechanism from electron to energy transfer.![]()
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Affiliation(s)
- Mark John P. Mandigma
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Jonas Žurauskas
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Callum I. MacGregor
- GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - Lee J. Edwards
- GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - Ahmed Shahin
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
- Chemistry Department, Faculty of Science, Benha University, 13518 Benha, Egypt
| | - Ludwig d'Heureuse
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Philip Yip
- Department of Physics, SUPA, University of Strathclyde, 107 Rottenrow East, Glasgow, G4 0NG, UK
| | - David J. S. Birch
- Department of Physics, SUPA, University of Strathclyde, 107 Rottenrow East, Glasgow, G4 0NG, UK
| | - Thomas Gruber
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Jörg Heilmann
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Matthew P. John
- GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - Joshua P. Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
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24
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Wang DJ, Targos K, Wickens ZK. Electrochemical Synthesis of Allylic Amines from Terminal Alkenes and Secondary Amines. J Am Chem Soc 2021; 143:21503-21510. [PMID: 34914394 DOI: 10.1021/jacs.1c11763] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Allylic amines are valuable synthetic targets en route to diverse biologically active amine products. Current allylic C-H amination strategies remain limited with respect to the viable N-substituents. Herein, we disclose a new electrochemical process to prepare aliphatic allylic amines by coupling two abundant starting materials: secondary amines and unactivated alkenes. This oxidative transformation proceeds via electrochemical generation of an electrophilic adduct between thianthrene and the alkene substrates. Treatment of these adducts with aliphatic amine nucleophiles and base provides allylic amine products in high yield. This synthetic strategy is also amenable to functionalization of feedstock gaseous alkenes at 1 atm. In the case of 1-butene, high Z-selective crotylation is observed. This strategy, however, is not limited to the synthesis of simple building blocks; complex biologically active molecules are suitable as both alkene and amine coupling partners. Preliminary mechanistic studies implicate vinylthianthrenium salts as key reactive intermediates.
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Affiliation(s)
- Diana J Wang
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Karina Targos
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Zachary K Wickens
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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25
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Shen Y, Funez-Ardoiz I, Schoenebeck F, Rovis T. Site-Selective α-C-H Functionalization of Trialkylamines via Reversible Hydrogen Atom Transfer Catalysis. J Am Chem Soc 2021; 143:18952-18959. [PMID: 34738467 DOI: 10.1021/jacs.1c07144] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Trialkylamines are widely found in naturally occurring alkaloids, synthetic agrochemicals, biological probes, and especially pharmaceuticals agents and preclinical candidates. Despite the recent breakthrough of catalytic alkylation of dialkylamines, the selective α-C(sp3)-H bond functionalization of widely available trialkylamine scaffolds holds promise to streamline complex trialkylamine synthesis, accelerate drug discovery, and execute late-stage pharmaceutical modification with complementary reactivity. However, the canonical methods always result in functionalization at the less-crowded site. Herein, we describe a solution to switch the reaction site through fundamentally overcoming the steric control that dominates such processes. By rapidly establishing an equilibrium between α-amino C(sp3)-H bonds and a highly electrophilic thiol radical via reversible hydrogen atom transfer, we leverage a slower radical-trapping step with electron-deficient olefins to selectively forge a C(sp3)-C(sp3) bond with the more-crowded α-amino radical, with the overall selectivity guided by the Curtin-Hammett principle. This subtle reaction profile has unlocked a new strategic concept in direct C-H functionalization arena for forging C-C bonds from a diverse set of trialkylamines with high levels of site selectivity and preparative utility. Simple correlation of site selectivity and 13C NMR shift serves as a qualitative predictive guide. The broad consequences of this dynamic system, together with the ability to forge N-substituted quaternary carbon centers and implement late-stage functionalization techniques, hold potential to streamline complex trialkylamine synthesis and accelerate small-molecule drug discovery.
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Affiliation(s)
- Yangyang Shen
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | | | | | - Tomislav Rovis
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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26
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Shen Y, Rovis T. Late-Stage N-Me Selective Arylation of Trialkylamines Enabled by Ni/Photoredox Dual Catalysis. J Am Chem Soc 2021; 143:16364-16369. [PMID: 34590864 PMCID: PMC8862118 DOI: 10.1021/jacs.1c08157] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The diversity and wide availability of trialkylamines render them ideal sources for rapid construction of complex amine architectures. Herein, we report that a nickel/photoredox dual catalysis strategy affects site-selective α-arylation of various trialkylamines. Our catalytic system shows exclusive N-Me selectivity with a wide range of trialkylamines under mild conditions, even in the context of late-stage arylation of pharmaceutical compounds bearing this common structural motif. Mechanistic studies indicate the unconventional behavior of Ni catalyst upon intercepting the α-amino radicals, in which only the primary α-amino radical undergoes a successful cross-coupling process.
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Affiliation(s)
- Yangyang Shen
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Tomislav Rovis
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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27
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Cp*Ir complex bearing a flexible bridging and functional 2,2′-methylenebibenzimidazole ligand as an auto-tandem catalyst for the synthesis of N-methyl tertiary amines from imines via transfer hydrogenation/N-methylation with methanol. J Catal 2021. [DOI: 10.1016/j.jcat.2021.08.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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28
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Wu S, Kaur J, Karl TA, Tian X, Barham JP. Synthetic Molecular Photoelectrochemistry: New Frontiers in Synthetic Applications, Mechanistic Insights and Scalability. Angew Chem Int Ed Engl 2021; 61:e202107811. [PMID: 34478188 PMCID: PMC9303540 DOI: 10.1002/anie.202107811] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Indexed: 11/11/2022]
Abstract
Synthetic photoelectrochemistry (PEC) is receiving increasing attention as a new frontier for the generation and handling of reactive intermediates. PEC permits selective single‐electron transfer (SET) reactions in a much greener way and broadens the redox window of possible transformations. Herein, the most recent contributions are reviewed, demonstrating exciting new opportunities, namely, the combination of PEC with other reactivity paradigms (hydrogen‐atom transfer, radical polar crossover, energy transfer sensitization), scalability up to multigram scale, novel selectivities in SET super‐oxidations/reductions and the importance of precomplexation to temporally enable excited radical ion catalysis.
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Affiliation(s)
- Shangze Wu
- University of Regensburg: Universitat Regensburg, Fakultät für Chemie und Pharmazie, GERMANY
| | - Jaspreet Kaur
- University of Regensburg: Universitat Regensburg, Fakultät für Chemie und Pharmazie, GERMANY
| | - Tobias A Karl
- University of Regensburg: Universitat Regensburg, Fakultät für Chemie und Pharmazie, GERMANY
| | - Xianhai Tian
- University of Regensburg: Universitat Regensburg, Fakultät für Chemie und Pharmazie, GERMANY
| | - Joshua Philip Barham
- Universitat Regensburg, Fakultat fur Chemie und Pharmazie, Universität Regensburg, Fakultät für Chemie und Pharmazie, 93040, Regensburg, GERMANY
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29
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Neveselý T, Wienhold M, Molloy JJ, Gilmour R. Advances in the E → Z Isomerization of Alkenes Using Small Molecule Photocatalysts. Chem Rev 2021; 122:2650-2694. [PMID: 34449198 DOI: 10.1021/acs.chemrev.1c00324] [Citation(s) in RCA: 155] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Geometrical E → Z alkene isomerization is intimately entwined in the historical fabric of organic photochemistry and is enjoying a renaissance (Roth et al. Angew. Chem., Int. Ed. Engl. 1989 28, 1193-1207). This is a consequence of the fundamental stereochemical importance of Z-alkenes, juxtaposed with frustrations in thermal reactivity that are rooted in microscopic reversibility. Accessing excited state reactivity paradigms allow this latter obstacle to be circumnavigated by exploiting subtle differences in the photophysical behavior of the substrate and product chromophores: this provides a molecular basis for directionality. While direct irradiation is operationally simple, photosensitization via selective energy transfer enables augmentation of the alkene repertoire to include substrates that are not directly excited by photons. Through sustained innovation, an impressive portfolio of tailored small molecule catalysts with a range of triplet energies are now widely available to facilitate contra-thermodynamic and thermo-neutral isomerization reactions to generate Z-alkene fragments. This review is intended to serve as a practical guide covering the geometric isomerization of alkenes enabled by energy transfer catalysis from 2000 to 2020, and as a logical sequel to the excellent treatment by Dugave and Demange (Chem. Rev. 2003 103, 2475-2532). The mechanistic foundations underpinning isomerization selectivity are discussed together with induction models and rationales to explain the counterintuitive directionality of these processes in which very small energy differences distinguish substrate from product. Implications for subsequent stereospecific transformations, application in total synthesis, regioselective polyene isomerization, and spatiotemporal control of pre-existing alkene configuration in a broader sense are discussed.
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Affiliation(s)
- Tomáš Neveselý
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Max Wienhold
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - John J Molloy
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Ryan Gilmour
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Münster, Germany
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30
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Bell JD, Murphy JA. Recent advances in visible light-activated radical coupling reactions triggered by (i) ruthenium, (ii) iridium and (iii) organic photoredox agents. Chem Soc Rev 2021; 50:9540-9685. [PMID: 34309610 DOI: 10.1039/d1cs00311a] [Citation(s) in RCA: 139] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Photoredox chemistry with organic or transition metal agents has been reviewed in earlier years, but such is the pace of progress that we will overlap very little with earlier comprehensive reviews. This review first presents an overview of the area of research and then examines recent examples of C-C, C-N, C-O and C-S bond formations via radical intermediates with transition metal and organic radical promoters. Recent successes with Birch reductions are also included. The transition metal chemistry will be restricted to photocatalysts based on the most widely used metals, Ru and Ir, but includes coupling chemistries that take advantage of low-valent nickel, or occasionally copper, complexes to process the radicals that are formed. Our focus is on developments in the past 10 years (2011-2021). This period has also seen great advances in the chemistry of organic photoredox reagents and the review covers this area. The review is intended to present highlights and is not comprehensive.
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Affiliation(s)
- Jonathan D Bell
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
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31
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Bergamaschi E, Weike C, Mayerhofer VJ, Funes-Ardoiz I, Teskey CJ. Dual Photoredox/Cobaloxime Catalysis for Cross-Dehydrogenative α-Heteroarylation of Amines. Org Lett 2021; 23:5378-5382. [PMID: 34196560 DOI: 10.1021/acs.orglett.1c01703] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report a dual-catalytic platform for the cross-dehydrogenative-coupling between (benzo-)thiazoles and amines which combines low loadings of an iridium photoredox catalyst and a cobaloxime catalyst under blue light irradiation. This transformation occurs without stoichiometric oxidants, giving products in moderate to excellent yields. DFT calculations support the key role of Co(II) for rearomatization of the radical-addition intermediate to generate the product.
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Affiliation(s)
- Enrico Bergamaschi
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Christopher Weike
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Victor J Mayerhofer
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Ignacio Funes-Ardoiz
- Department of Chemistry, Centro de Investigación en Síntesis Química (CISQ), Universidad de La Rioja, Madre de Dios 53, 26006 Logroño, Spain
| | - Christopher J Teskey
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
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32
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Najmi AA, Bhat MF, Bischoff R, Poelarends GJ, Permentier HP. TEMPO‐Mediated Electrochemical N‐demethylation of Opiate Alkaloids. ChemElectroChem 2021. [DOI: 10.1002/celc.202100784] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Ali Alipour Najmi
- Department of Analytical Biochemistry Groningen Research Institute of Pharmacy University of Groningen A. Deusinglaan 1 9713 AV Groningen The Netherlands
| | - M. Faizan Bhat
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen A. Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Rainer Bischoff
- Department of Analytical Biochemistry Groningen Research Institute of Pharmacy University of Groningen A. Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen A. Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Hjalmar P. Permentier
- Department of Analytical Biochemistry Groningen Research Institute of Pharmacy University of Groningen A. Deusinglaan 1 9713 AV Groningen The Netherlands
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33
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Kaur J, Shahin A, Barham JP. Photocatalyst-Free, Visible-Light-Mediated C(sp3)–H Arylation of Amides via a Solvent-Caged EDA Complex. Org Lett 2021; 23:2002-2006. [PMID: 33596084 DOI: 10.1021/acs.orglett.1c00132] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Jaspreet Kaur
- Universität Regensburg, Fakultät für Chemie und Pharmazie, 93040 Regensburg, Germany
| | - Ahmed Shahin
- Universität Regensburg, Fakultät für Chemie und Pharmazie, 93040 Regensburg, Germany
- Chemistry Department, Faculty of Science, Benha University, 13518 Benha, Egypt
| | - Joshua P. Barham
- Universität Regensburg, Fakultät für Chemie und Pharmazie, 93040 Regensburg, Germany
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34
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Lewis BW, Bisballe N, Santella M, Summers PA, Vannier JB, Kuimova MK, Laursen BW, Vilar R. Assessing The Key Photophysical Properties of Triangulenium Dyes for DNA Binding by Alteration of the Fluorescent Core. Chemistry 2021; 27:2523-2536. [PMID: 33105523 DOI: 10.1002/chem.202003875] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Indexed: 11/09/2022]
Abstract
Four-stranded G-quadruplex (G4) DNA is a non-canonical DNA topology that has been proposed to form in cells and play key roles in how the genome is read and used by the cellular machinery. Previously, a fluorescent triangulenium probe (DAOTA-M2) was used to visualise G4s in cellulo, thanks to its distinct fluorescence lifetimes when bound to different DNA topologies. Herein, the library of available triangulenium probes is expanded to explore how modifications to the fluorescent core of the molecule affect its photophysical characteristics, interaction with DNA and cellular localisation. The benzo-bridged and isopropyl-bridged diazatriangulenium dyes, BDATA-M2 and CDATA-M2 respectively, featuring ethyl-morpholino substituents, were synthesised and characterised. The interactions of these molecules with different DNA topologies were studied to determine their binding affinity, fluorescence enhancement and fluorescence lifetime response. Finally, the cellular uptake and localisation of these optical probes were investigated. Whilst structural modifications to the triangulenium core only slightly alter the binding affinity to DNA, BDATA-M2 and CDATA-M2 cannot distinguish between DNA topologies through their fluorescence lifetime. It is argued theoretically and experimentally that this is due to reduced effectiveness of photoinduced electron transfer (PET) quenching. This work presents valuable new evidence into the critical role of PET quenching when using the fluorescence lifetime of triangulenium dyes to discriminate G4 DNA from duplex DNA, highlighting the importance of fine tuning redox and spectral properties when developing new triangulenium-based G4 probes.
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Affiliation(s)
- Benjamin W Lewis
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, London, W12 0BZ, UK.,Institute of Chemical Biology, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Niels Bisballe
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Marco Santella
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Peter A Summers
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Jean-Baptiste Vannier
- Telomere Replication and Stability Group, Medical Research Council-London Institute of Medical Sciences, London, W12 0NN, UK.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Marina K Kuimova
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, London, W12 0BZ, UK.,Institute of Chemical Biology, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Bo W Laursen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Ramon Vilar
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, London, W12 0BZ, UK.,Institute of Chemical Biology, White City Campus, Imperial College London, London, W12 0BZ, UK
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35
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Das S, Murugesan K, Villegas Rodríguez GJ, Kaur J, Barham JP, Savateev A, Antonietti M, König B. Photocatalytic (Het)arylation of C(sp3)–H Bonds with Carbon Nitride. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05694] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Saikat Das
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Kathiravan Murugesan
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | | | - Jaspreet Kaur
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Joshua P. Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Aleksandr Savateev
- Department of Colloid Chemistry, Max-Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany
| | - Markus Antonietti
- Department of Colloid Chemistry, Max-Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany
| | - Burkhard König
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
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36
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Ma C, Feng Z, Li J, Zhang D, Li W, Jiang Y, Yu B. Photocatalytic transition-metal-free direct 3-alkylation of 2-aryl-2 H-indazoles in dimethyl carbonate. Org Chem Front 2021. [DOI: 10.1039/d1qo00064k] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A general transition-metal-free photocatalytic decarboxylative 3-alkylation reaction of 2-aryl-2H-indazoles was developed under visible-light irradiation under mild conditions.
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Affiliation(s)
- Chunhua Ma
- Collaborative Innovation Centre of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
- Henan Engineering Research Centre of Chiral Hydroxyl Pharmaceutical
- Henan Engineering Laboratory of Chemical Pharmaceutical and Biomedical Materials
| | - Zhiwen Feng
- Collaborative Innovation Centre of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
- Henan Engineering Research Centre of Chiral Hydroxyl Pharmaceutical
- Henan Engineering Laboratory of Chemical Pharmaceutical and Biomedical Materials
| | - Jing Li
- Collaborative Innovation Centre of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
- Henan Engineering Research Centre of Chiral Hydroxyl Pharmaceutical
- Henan Engineering Laboratory of Chemical Pharmaceutical and Biomedical Materials
| | - Dandan Zhang
- Collaborative Innovation Centre of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
- Henan Engineering Research Centre of Chiral Hydroxyl Pharmaceutical
- Henan Engineering Laboratory of Chemical Pharmaceutical and Biomedical Materials
| | - Wei Li
- Collaborative Innovation Centre of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
- Henan Engineering Research Centre of Chiral Hydroxyl Pharmaceutical
- Henan Engineering Laboratory of Chemical Pharmaceutical and Biomedical Materials
| | - Yuqin Jiang
- Collaborative Innovation Centre of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
- Henan Engineering Research Centre of Chiral Hydroxyl Pharmaceutical
- Henan Engineering Laboratory of Chemical Pharmaceutical and Biomedical Materials
| | - Bing Yu
- Green Catalysis Centre
- College of Chemistry
- Zhengzhou University
- Zhengzhou 450001
- China
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37
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Wu S, Žurauskas J, Domański M, Hitzfeld PS, Butera V, Scott DJ, Rehbein J, Kumar A, Thyrhaug E, Hauer J, Barham JP. Hole-mediated photoredox catalysis: tris(p-substituted)biarylaminium radical cations as tunable, precomplexing and potent photooxidants. Org Chem Front 2021. [DOI: 10.1039/d0qo01609h] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Triarylamines are demonstrated as novel, tunable electroactivated photocatalysts that use dispersion precomplexation to harness the full potential of the visible photon (>4.0 V vs. SCE) in anti-Kasha photo(electro)chemical super-oxidations of arenes.
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Affiliation(s)
- Shangze Wu
- Universität Regensburg
- Fakültat für Chemie und Pharmazie
- 93040 Regensburg
- Germany
| | - Jonas Žurauskas
- Universität Regensburg
- Fakültat für Chemie und Pharmazie
- 93040 Regensburg
- Germany
| | - Michał Domański
- Universität Regensburg
- Fakültat für Chemie und Pharmazie
- 93040 Regensburg
- Germany
| | - Patrick S. Hitzfeld
- Universität Regensburg
- Fakültat für Chemie und Pharmazie
- 93040 Regensburg
- Germany
| | - Valeria Butera
- Central European Institute of Technology
- CEITEC
- 61200 Brno
- Czech Republic
| | - Daniel J. Scott
- Universität Regensburg
- Fakültat für Chemie und Pharmazie
- 93040 Regensburg
- Germany
| | - Julia Rehbein
- Universität Regensburg
- Fakültat für Chemie und Pharmazie
- 93040 Regensburg
- Germany
| | - Ajeet Kumar
- Technische Universität München
- Fakültat für Chemie
- 85748 Garching b. München
- Germany
| | - Erling Thyrhaug
- Technische Universität München
- Fakültat für Chemie
- 85748 Garching b. München
- Germany
| | - Jürgen Hauer
- Technische Universität München
- Fakültat für Chemie
- 85748 Garching b. München
- Germany
| | - Joshua P. Barham
- Universität Regensburg
- Fakültat für Chemie und Pharmazie
- 93040 Regensburg
- Germany
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38
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Afanasyev OI, Kuchuk EA, Muratov KM, Denisov GL, Chusov D. Symmetrical Tertiary Amines: Applications and Synthetic Approaches. European J Org Chem 2020. [DOI: 10.1002/ejoc.202001171] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Oleg I. Afanasyev
- A. N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences Vavilova St. 28 Moscow 119991 Russian Federation
| | - Ekaterina A. Kuchuk
- A. N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences Vavilova St. 28 Moscow 119991 Russian Federation
| | - Karim M. Muratov
- A. N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences Vavilova St. 28 Moscow 119991 Russian Federation
| | - Gleb L. Denisov
- A. N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences Vavilova St. 28 Moscow 119991 Russian Federation
| | - Denis Chusov
- A. N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences Vavilova St. 28 Moscow 119991 Russian Federation
- National Research University Higher School of Economics Miasnitskaya Str. 20 Moscow 101000 Russian Federation
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39
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Kallepu S, Neeli PK, Mallappa S, Nagendla NK, Reddy Mudiam MK, Mainkar PS, Kotamraju S, Chandrasekhar S. sp 3 -Rich Glycyrrhetinic Acid Analogues Using Late-Stage Functionalization as Potential Breast Tumor Regressing Agents. ChemMedChem 2020; 15:1826-1833. [PMID: 32893968 DOI: 10.1002/cmdc.202000400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Indexed: 12/28/2022]
Abstract
Late-stage functionalization (LSF) aids drug discovery efforts by introducing functional groups onto C-H bonds on pre-existing skeletons. We adopted the LSF strategy to synthesize analogues of the abundantly available triterpenoid, glycyrrhetinic acid (GA), by introducing aryl groups in the A-ring, expanding the A-ring and selectively activating one methyl group of the gem-dimethyl groups. Intriguingly, two compounds were found to preferentially accumulate in the mitochondrial compartment of MDA-MB-231 breast cancer cells, to cause depolarization of mitochondrial membrane potential and to induce antiproliferative and anti-invasive effects through enhanced mitochondrial superoxide production with parallel depletion of GSH levels. Furthermore, intraperitoneal administration of these two compounds, in comparison with GA, greatly regressed breast tumor growth and metastasis in a SCID mouse model bearing labeled MDA-MB-231 cells.
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Affiliation(s)
- Shivakrishna Kallepu
- Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India
| | - Praveen Kumar Neeli
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India
| | - Sreevidya Mallappa
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India
| | - Narendra Kumar Nagendla
- Department of Analytical & Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India
| | - Mohana Krishna Reddy Mudiam
- Department of Analytical & Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India
| | - Prathama S Mainkar
- Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India
| | - Srigiridhar Kotamraju
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India
| | - Srivari Chandrasekhar
- Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India
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40
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Yakubov S, Barham JP. Photosensitized direct C-H fluorination and trifluoromethylation in organic synthesis. Beilstein J Org Chem 2020; 16:2151-2192. [PMID: 32952732 PMCID: PMC7476599 DOI: 10.3762/bjoc.16.183] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/17/2020] [Indexed: 12/11/2022] Open
Abstract
The importance of fluorinated products in pharmaceutical and medicinal chemistry has necessitated the development of synthetic fluorination methods, of which direct C-H fluorination is among the most powerful. Despite the challenges and limitations associated with the direct fluorination of unactivated C-H bonds, appreciable advancements in manipulating the selectivity and reactivity have been made, especially via transition metal catalysis and photochemistry. Where transition metal catalysis provides one strategy for C-H bond activation, transition-metal-free photochemical C-H fluorination can provide a complementary selectivity via a radical mechanism that proceeds under milder conditions than thermal radical activation methods. One exciting development in C-F bond formation is the use of small-molecule photosensitizers, allowing the reactions i) to proceed under mild conditions, ii) to be user-friendly, iii) to be cost-effective and iv) to be more amenable to scalability than typical photoredox-catalyzed methods. In this review, we highlight photosensitized C-H fluorination as a recent strategy for the direct and remote activation of C-H (especially C(sp3)-H) bonds. To guide the readers, we present the developing mechanistic understandings of these reactions and exemplify concepts to assist the future planning of reactions.
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Affiliation(s)
- Shahboz Yakubov
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
| | - Joshua P Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
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41
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Kriegelstein M, Profous D, Přibylka A, Cankař P. The Assignment of the Absolute Configuration of β-Chiral Primary Alcohols with Axially Chiral Trifluoromethylbenzimidazolylbenzoic Acid. J Org Chem 2020; 85:12912-12921. [DOI: 10.1021/acs.joc.0c01510] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Michal Kriegelstein
- Department of Organic Chemistry, Faculty of Science, Palacký University, 17. Listopadu 12, 771 46 Olomouc, Czech Republic
| | - David Profous
- Department of Organic Chemistry, Faculty of Science, Palacký University, 17. Listopadu 12, 771 46 Olomouc, Czech Republic
| | - Adam Přibylka
- Department of Organic Chemistry, Faculty of Science, Palacký University, 17. Listopadu 12, 771 46 Olomouc, Czech Republic
| | - Petr Cankař
- Department of Organic Chemistry, Faculty of Science, Palacký University, 17. Listopadu 12, 771 46 Olomouc, Czech Republic
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42
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Dong Q, Wang T, Gan R, Fu N, Li C, Wei Z. Balancing the Seesaw: Investigation of a Separator to Grasp Polysulfides with Diatomic Chemisorption. ACS APPLIED MATERIALS & INTERFACES 2020; 12:20596-20604. [PMID: 32281778 DOI: 10.1021/acsami.0c04554] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Lithium-sulfur (Li-S) batteries are promising next-generation high-density energy storage systems due to their advantages of high theoretical specific capacity, environmental compatibility, and low cost. However, high-order polysulfides dissolve in the electrolyte and subsequently lead to the undesired polysulfide shuttle effect, which hinders the commercialization of Li-S batteries. To tackle this issue, morpholine molecules were successfully grafted onto a commercial polypropylene separator. Density functional theory (DFT) calculations were performed and revealed that morpholine side chains could equally and reversibly grasp all the high-order polysulfides. This diatomic chemisorption adjusted the transformation process among the sulfur-related compounds. The modified separator battery possessed a discharge capacity as high as 827.8 mAh·g-1 after 500 cycles at 0.5 C. The low capacity fading rate, symmetrical cyclic voltammogram, and retention of the electrode morphology all suggest that the diatomic equal adsorption approach can successfully suppress the polysulfide shuttle effect while maintaining excellent battery performance.
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Affiliation(s)
- Qin Dong
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Tao Wang
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Ruiyi Gan
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Na Fu
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Cunpu Li
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Zidong Wei
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
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43
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Bugaenko DI, Karchava AV, Yurovskaya MA. The versatility of DABCO: synthetic applications of its basic, nucleophilic, and catalytic properties. Chem Heterocycl Compd (N Y) 2020. [DOI: 10.1007/s10593-020-02655-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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44
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Wang H, Gao Y, Zhou C, Li G. Visible-Light-Driven Reductive Carboarylation of Styrenes with CO2 and Aryl Halides. J Am Chem Soc 2020; 142:8122-8129. [DOI: 10.1021/jacs.0c03144] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Hao Wang
- Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, Fujian, China
- Fujian College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuzhen Gao
- Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, Fujian, China
| | - Chunlin Zhou
- Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, Fujian, China
- Fujian College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Gang Li
- Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, Fujian, China
- Fujian College, University of Chinese Academy of Sciences, Beijing 100049, China
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45
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Barham JP, Fouquet TNJ, Norikane Y. Base-catalyzed C-alkylation of potassium enolates with styrenes via a metal-ene reaction: a mechanistic study. Org Biomol Chem 2020; 18:2063-2075. [PMID: 32100777 DOI: 10.1039/c9ob02495f] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Base-catalyzed, C-alkylation of potassium (K) enolates with styrenes (CAKES) has recently emerged as a highly practical and convenient method for elaboration or synthesis of pharmaceutically-relevant cores. K enolate-type precursors such as alkyl-substituted heterocycles (pyridines, pyrazines and thiophenes), ketones, imines, nitriles and amides undergo C-alkylation reactions with styrene in the presence of KOtBu or KHMDS. Surprisingly, no studies have probed the reaction mechanism beyond the likely initial formation of a K enolate. Herein, a synergistic approach of computational (DFT), kinetic and deuterium labelling studies rationalizes various experimental observations and supports a metal-ene-type reaction for amide CAKES. Moreover, our approach explains experimental observations in other reported C-alkylation reactions of other enolate-type precursors, thus implicating a general mechanism for CAKES.
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Affiliation(s)
- Joshua P Barham
- National Institute of Advanced Industrial Science and Technology, Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
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46
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Toward Rational Understandings of α-C-H Functionalization: Energetic Studies of Representative Tertiary Amines. iScience 2020; 23:100851. [PMID: 32058963 PMCID: PMC6997867 DOI: 10.1016/j.isci.2020.100851] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 12/31/2019] [Accepted: 01/14/2020] [Indexed: 12/17/2022] Open
Abstract
Functionalization of α-C–H bonds of tertiary amines to build various α-C–X bonds has become a mainstream in synthetic chemistry nowadays. However, due to lack of fundamental knowledge on α-C–H bond strength as an energetic guideline, rational exploration of new synthetic methodologies remains a far-reaching anticipation. Herein, we report a unique hydricity-based approach to establish the first integrated energetic scale covering both the homolytic and heterolytic energies of α-C–H bonds for 45 representative tertiary amines and their radical cations. As showcased from the studies on tetrahydroisoquinolines (THIQs) by virtue of their thermodynamic criteria, the feasibility and mechanisms of THIQ oxidation were deduced, which, indeed, were found to correspond well with experimental observations. This integrated scale provides a good example to relate bond energetics with mechanisms and thermodynamic reactivity of amine α-C–H functionalization and hence, may be referenced for analyzing similar structure-property problems for various substrates. A unique hydricity-based methodology for bond energy determination The first integrated α-C–H bond energy scale of tertiary amines Thermodynamics-based diagnosis of the feasibility/mechanism of amine oxidation
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47
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Yamamoto Y, Shimizu E, Ban K, Wada Y, Mizusaki T, Yoshimura M, Takagi Y, Sawama Y, Sajiki H. Facile Hydrogenative Deprotection of N-Benzyl Groups Using a Mixed Catalyst of Palladium and Niobic Acid-on-Carbon. ACS OMEGA 2020; 5:2699-2709. [PMID: 32095693 PMCID: PMC7033673 DOI: 10.1021/acsomega.9b03226] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 01/21/2020] [Indexed: 05/12/2023]
Abstract
The palladium-on-carbon (Pd/C)-catalyzed hydrogenative deprotection of the N-benzyl-protecting group was effectively facilitated by the combined use of niobic acid-on-carbon (Nb2O5/C). Nb2O5/C is an acidic heterogeneous catalyst prepared from NbCl5 and activated carbon. The catalysts were easily removed from the reaction mixture and reusable. Deprotected amines were obtained in excellent yields without an additional neutralization process. The facilitating effect of Nb2O5/C was also observed during the Pd/C-catalyzed hydrogenative deprotection of the N-benzyloxycarbonyl (Cbz) and O-benzyl groups.
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Affiliation(s)
- Yuta Yamamoto
- Laboratory
of Organic Chemistry, Gifu Pharmaceutical
University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
| | - Eisho Shimizu
- Laboratory
of Organic Chemistry, Gifu Pharmaceutical
University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
| | - Kazuho Ban
- Laboratory
of Organic Chemistry, Gifu Pharmaceutical
University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
| | - Yoshiyuki Wada
- Catalysts
Development Center, N. E. Chemcat Corporation, 25-3 Koshindaira, Bando, Ibaraki 306-0608, Japan
| | - Tomoteru Mizusaki
- Catalysts
Development Center, N. E. Chemcat Corporation, 25-3 Koshindaira, Bando, Ibaraki 306-0608, Japan
| | - Masatoshi Yoshimura
- Catalysts
Development Center, N. E. Chemcat Corporation, 678 Ipponmatsu, Numazu, Shizuoka 410-0314, Japan
| | - Yukio Takagi
- Catalysts
Development Center, N. E. Chemcat Corporation, 678 Ipponmatsu, Numazu, Shizuoka 410-0314, Japan
| | - Yoshinari Sawama
- Laboratory
of Organic Chemistry, Gifu Pharmaceutical
University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
- E-mail: (Y.S.)
| | - Hironao Sajiki
- Laboratory
of Organic Chemistry, Gifu Pharmaceutical
University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
- E-mail: . Phone/Fax: (+81)-58-230-8109 (H.S.)
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48
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He J, Li J, Han Q, Si C, Niu G, Li M, Wang J, Niu J. Photoactive Metal-Organic Framework for the Reduction of Aryl Halides by the Synergistic Effect of Consecutive Photoinduced Electron-Transfer and Hydrogen-Atom-Transfer Processes. ACS APPLIED MATERIALS & INTERFACES 2020; 12:2199-2206. [PMID: 31859478 DOI: 10.1021/acsami.9b13538] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Consecutive photoinduced electron transfer (ConPET) has advantages on overcoming the current energetic limitation of visible-light photoredox catalysis for utilizing the energies of two photons in one catalytic cycle. A heterogeneous approach for radical chain reduction of various aryl bromides and chlorides without adding any cocatalyst is introduced by incorporating polyoxometalates (POMs) and amine catalysts into a naphthalenediimide (NDI)-based polymer. CoW-DPNDI-PYI exhibits high activity in the photocatalytic reduction of aryl halides by the synergistic effects of ConPET and hydrogen-atom-transfer (HAT) processes and an enzyme-mimicking CO2 cycloaddition reaction. The ConPET process with N,N'-bis(4-pyridylmethyl)naphthalenediimide (DPNDI) facilitates effective solar energy conversion. POMs and amine catalysts, as efficient HAT catalysts and electron donors, improve the generation of the ConPET process. The success of this work demonstrates the great application of the synergistic effects of ConPET and HAT processes in heterogeneous photocatalysis C-H arylation.
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Affiliation(s)
- Jiachen He
- Key Laboratory of Polyoxometalate Chemistry of Henan Province, School of Chemistry and Chemical Engineering , Henan University , Kaifeng 475004 , P. R. China
| | - Jie Li
- Key Laboratory of Polyoxometalate Chemistry of Henan Province, School of Chemistry and Chemical Engineering , Henan University , Kaifeng 475004 , P. R. China
| | - Qiuxia Han
- Key Laboratory of Polyoxometalate Chemistry of Henan Province, School of Chemistry and Chemical Engineering , Henan University , Kaifeng 475004 , P. R. China
| | - Chen Si
- Key Laboratory of Polyoxometalate Chemistry of Henan Province, School of Chemistry and Chemical Engineering , Henan University , Kaifeng 475004 , P. R. China
| | - Guiqin Niu
- Key Laboratory of Polyoxometalate Chemistry of Henan Province, School of Chemistry and Chemical Engineering , Henan University , Kaifeng 475004 , P. R. China
| | - Mingxue Li
- Key Laboratory of Polyoxometalate Chemistry of Henan Province, School of Chemistry and Chemical Engineering , Henan University , Kaifeng 475004 , P. R. China
| | - Jingping Wang
- Key Laboratory of Polyoxometalate Chemistry of Henan Province, School of Chemistry and Chemical Engineering , Henan University , Kaifeng 475004 , P. R. China
| | - Jingyang Niu
- Key Laboratory of Polyoxometalate Chemistry of Henan Province, School of Chemistry and Chemical Engineering , Henan University , Kaifeng 475004 , P. R. China
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49
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Verma A, Singh Banjara L, Meena R, Kumar S. Transition‐Metal‐Free Synthesis of N‐Substituted Phenanthridinones and Spiro‐isoindolinones: C(
sp
2
)−N and C(
sp
2
)−O Coupling through Radical Pathway. ASIAN J ORG CHEM 2020. [DOI: 10.1002/ajoc.201900704] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Ajay Verma
- Department of ChemistryIndian Institute of Science Education and Research Bhopal Bhopal By-pass Road Bhauri, Bhopal, Madhya Pradesh 462066 India
| | - Lal Singh Banjara
- Department of ChemistryIndian Institute of Science Education and Research Bhopal Bhopal By-pass Road Bhauri, Bhopal, Madhya Pradesh 462066 India
| | - Rahul Meena
- Department of ChemistryIndian Institute of Science Education and Research Bhopal Bhopal By-pass Road Bhauri, Bhopal, Madhya Pradesh 462066 India
| | - Sangit Kumar
- Department of ChemistryIndian Institute of Science Education and Research Bhopal Bhopal By-pass Road Bhauri, Bhopal, Madhya Pradesh 462066 India
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50
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Huang B, Yang C, Zhou J, Xia W. Electrochemically generated N-iodoaminium species as key intermediates for selective methyl sulphonylimination of tertiary amines. Chem Commun (Camb) 2020; 56:5010-5013. [DOI: 10.1039/c9cc09869k] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study presents a straightforward protocol for approaching N-sulphonylamidines via an electricity-driven, iodine-mediated cross dehydrogenative condensation (CDC) between sulphonamides and tertiary amines.
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Affiliation(s)
- Binbin Huang
- State Key Lab of Urban Water Resource and Environment
- School of Science, Harbin Institute of Technology (Shenzhen)
- Shenzhen 518055
- China
| | - Chao Yang
- State Key Lab of Urban Water Resource and Environment
- School of Science, Harbin Institute of Technology (Shenzhen)
- Shenzhen 518055
- China
| | - Jia Zhou
- State Key Lab of Urban Water Resource and Environment
- School of Science, Harbin Institute of Technology (Shenzhen)
- Shenzhen 518055
- China
| | - Wujiong Xia
- State Key Lab of Urban Water Resource and Environment
- School of Science, Harbin Institute of Technology (Shenzhen)
- Shenzhen 518055
- China
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