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Holt E, Wang M, Harry SA, He C, Wang Y, Henriquez N, Xiang MR, Zhu A, Ghorbani F, Lectka T. An Electrochemical Approach to Directed Fluorination. J Org Chem 2023; 88:2557-2560. [PMID: 36702475 DOI: 10.1021/acs.joc.2c01886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Electrosynthesis has made a revival in the field of organic chemistry and, in particular, radical-mediated reactions. Herein, we report a simple directed, electrochemical C-H fluorination method. Employing a dabconium mediator, commercially available Selectfluor, and RVC electrodes, we provide a range of steroid-based substrates with competent regioselective directing groups, including enones, ketones, and hydroxy groups, as well as never reported before lactams, imides, lactones, and esters.
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Affiliation(s)
- Eric Holt
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Muyuan Wang
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Stefan Andrew Harry
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Chengkun He
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Yuang Wang
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Nicolas Henriquez
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Michael Richard Xiang
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Andrea Zhu
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Fereshte Ghorbani
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Thomas Lectka
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
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Berger M, Lenhard MS, Waldvogel SR. Para-Fluorination of Anilides Using Electrochemically Generated Hypervalent Iodoarenes. Chemistry 2022; 28:e202201029. [PMID: 35510825 PMCID: PMC9401020 DOI: 10.1002/chem.202201029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Indexed: 11/23/2022]
Abstract
The para-selective fluorination reaction of anilides using electrochemically generated hypervalent ArIF2 is reported, with Et3 N ⋅ 5HF serving as fluoride source and as supporting electrolyte. This electrochemical reaction is characterized by a simple set-up, easy scalability and affords a broad variety of fluorinated anilides from easily accessible anilides in good yields up to 86 %.
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Affiliation(s)
- Michael Berger
- Department of ChemistryJohannes Gutenberg University MainzDuesbergweg 10–1455128MainzGermany
| | - Marola S. Lenhard
- Department of ChemistryJohannes Gutenberg University MainzDuesbergweg 10–1455128MainzGermany
| | - Siegfried R. Waldvogel
- Department of ChemistryJohannes Gutenberg University MainzDuesbergweg 10–1455128MainzGermany
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3
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Liu Z, Sun Y, Liu T. Recent Advances in Synthetic Methodologies to Form C-18F Bonds. Front Chem 2022; 10:883866. [PMID: 35494631 PMCID: PMC9047704 DOI: 10.3389/fchem.2022.883866] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 03/14/2022] [Indexed: 11/13/2022] Open
Abstract
Positron emission tomography (PET) is an important technique for the early diagnosis of disease. Due to the specific physical and chemical properties of Fluorine-18, this important isotope is widely used in PET for labelling and molecular imaging, and its introduction into medicine molecules could produce PET tracers. Developing with the development of organic synthetic methodologies, the introduction of Fluorine-18 into drug molecules efficiently and rapidly under mild conditions, and the formation of C-18F chemical bonds, has become one of the leading topics in both organic synthetic chemistry and radiochemistry. In this mini-review, we review a series of recent advances in the organic synthesis of C-18F bonds (2015–2021), including non-catalytic radiofluorinations via good leaving functional groups, transition metal-catalyzed radiofluorinations, and photo- or electro-catalytic synthetic radiofluorinations. As a result of the remarkable advancements in this field, organic synthetic methods for forming C-18F bonds are expected to continue growing.
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Affiliation(s)
- Zhiyi Liu
- State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin, China
- The Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Tianjin, China
| | - Yijun Sun
- State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin, China
- The Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Tianjin, China
| | - Tianfei Liu
- State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin, China
- The Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Tianjin, China
- Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- *Correspondence: Tianfei Liu,
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Allison N, Balandeh M, Holloway T, Gomez A, Rios A, Waldmann CM, Lebedev A, Sadeghi S. Electrochemical No-Carrier-Added Radiofluorination of Thioethers. J Fluor Chem 2022. [DOI: 10.1016/j.jfluchem.2022.109988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Hernández-Valdés D, Sadeghi S. Electrochemical Radiofluorination of Small Molecules: New Advances. CHEM REC 2021; 21:2397-2410. [PMID: 34010479 DOI: 10.1002/tcr.202100086] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/20/2021] [Indexed: 12/14/2022]
Abstract
The development of new 18 F-based radiopharmaceuticals constantly demands innovations in the search for new radiofluorination methods. [18 F]fluoride is the simplest and most convenient chemical form of the isotope for the synthesis of 18 F-based radiopharmaceuticals. The ease of production and handling, as well as the possibility of obtaining high molar activities, makes it the preferred choice for radiofluorination. However, the use of [18 F]fluoride in late-stage radiofluorination comes with challenges, especially for the radiolabeling of electron-rich molecules where SN 2 and SN Ar reactions are not suitable. New developments in fluorination chemistry have been extensively studied to overcome these difficulties. Selective electrochemical oxidation of precursors, using a controlled potential, is one method to create reactive intermediates and overcome the activation energy required for nucleophilic fluorination of electron-rich moieties. This method has been used for years in cold fluorination of organic molecules and more recently has been adapted as an alternative to traditional radiofluorination methods. Although relatively young, this field stands out as a promising route for the synthesis of new PET probes as well as fluorinated pharmaceuticals. This review focuses on recent advances in electrochemical radiofluorination as an alternative for the late-stage radiolabeling of organic molecules.
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Affiliation(s)
- Daniel Hernández-Valdés
- Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4 L8, Canada
| | - Saman Sadeghi
- Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4 L8, Canada.,Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
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Scheide MR, Nicoleti CR, Martins GM, Braga AL. Electrohalogenation of organic compounds. Org Biomol Chem 2021; 19:2578-2602. [DOI: 10.1039/d0ob02459g] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this review we target sp, sp2 and sp3 carbon fluorination, chlorination, bromination and iodination reactions using electrolysis as a redox medium. Mechanistic insights and substrate reactivity are also discussed.
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Affiliation(s)
- Marcos R. Scheide
- Departamento de Química
- Universidade Federal de Santa Catarina – UFSC
- Florianópolis
- Brazil
| | - Celso R. Nicoleti
- Departamento de Química
- Universidade Federal de Santa Catarina – UFSC
- Florianópolis
- Brazil
| | - Guilherme M. Martins
- Departamento de Química
- Universidade Federal de Santa Catarina – UFSC
- Florianópolis
- Brazil
| | - Antonio L. Braga
- Departamento de Química
- Universidade Federal de Santa Catarina – UFSC
- Florianópolis
- Brazil
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Fuchigami T, Inagi S. Recent Advances in Electrochemical Systems for Selective Fluorination of Organic Compounds. Acc Chem Res 2020; 53:322-334. [PMID: 32017527 DOI: 10.1021/acs.accounts.9b00520] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Organofluorine compounds are key materials applied in daily life because of their versatile utility as functional materials, pharmaceuticals, and agrochemicals. Development of the selective fluorination of organic molecules under safe conditions is therefore one of the most important subjects in modern synthetic organofluorine chemistry. Thus, various electrophilic fluorination reagents such as XeF2, (PhSO2)2NF (NFSI), Et2NSF3 (DAST), (MeOCH2CH2)2NSF3 (Deoxofluor), 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo-[2.2.2]octane bis(tetrafluoroborate) (Selectfluor), N-fluoropyridinium salts, and 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride (Fluolead) have been developed for chemical fluorination to date and the development of new fluorinating reagents is still ongoing. Electrochemical synthesis has recently attracted much attention from the perspective of green sustainable chemistry because no hazardous reagents are required and scale-up is generally easy. Although electrochemical perfluorination of organic compounds using a nickel anode in anhydrous HF has been well-established to manufacture perfluoro-functional materials, electrochemical partial fluorination (selective electrochemical fluorination) has been underdeveloped due to the low nucleophilicity of fluoride ions and anode passivation, which interferes with electrolysis. Selective electrochemical fluorination can be commonly achieved in aprotic solvents containing fluoride ions to provide mostly mono- and difluorinated products. Electrolysis is conducted at constant potentials slightly higher than the first oxidation potential of a substrate. Constant current electrolysis is also effective for selective fluorination in many cases. Choice of the combination of a supporting fluoride salt and an electrolytic solvent is most important to accomplish efficient selective fluorination. In this Account, we focus on our recent work on the electrochemical mono- and difluorination of various organic compounds and their synthetic application. We first briefly explain our research background of electrochemical fluorination. Main factors such as the effects of fluoride salts as supporting electrolytes, electrolytic solvents, and anode materials on the selectivity and efficiency of fluorination are discussed. Next, effects of PEG oligomer additives enhancing the nucleophilicity of fluoride ions and organic solvent-free systems using poly(HF) salt ionic liquids as well as recyclable mediatory systems for electrochemical fluorination are described. The desulfurizative monofluorination of xanthate and gem-difluorination of benzothioate and dithioacetals are briefly mentioned. Regioselective anodic fluorination of various heterocyclic compounds having a phenylthio group as electroauxiliary and heterocycles containing sulfur and other heteroatoms are also described. In addition, a boryl group is shown to be a good leaving group for anodic fluorination. Moreover, electrochemically α,α-difluorinated phenylsulfides and phenylselenides are illustrated to be useful for photochemical C-H difluoromethylation of aromatic and heteroaromatic compounds. Finally, this Account also highlights highly diastereoselective fluorination of aliphatic heterocyclic and open-chain compounds, as well as new electrolytic fluorination methods using inorganic fluoride salts such as KF and CsF.
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Affiliation(s)
- Toshio Fuchigami
- Department of Electronic Chemistry, Tokyo Institute of Technology, Nagatsuta, Yokohama 226-8502, Japan
| | - Shinsuke Inagi
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Nagatsuta, Yokohama 226-8502, Japan
- PRESTO, Japan Science and Technology Agency (JST) 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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Balandeh M, Rios A, Allison N, Shirazi D, Gomez A, Rambaran L, Holloway T, Sadeghi S. Electrochemical Flash Fluorination and Radiofluorination. ChemElectroChem 2018; 5:3353-3356. [PMID: 31475090 DOI: 10.1002/celc.201800973] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A new method for rapid late-stage fluorination using the cation pool technique is presented. Fluorination and no-carrier-added radiofluorination of methyl (phenylthio) acetate, methyl 2-(methylthio) acetate, and methyl 2-(ethylthio) acetate were performed. The carbocations formed through electrochemical oxidation were stabilized by using a divided electrochemical cell and 2,2,2-trifluoroethanol (TFE) as the solvent at -20 °C. At the end of electrolysis, either stable-isotope [19F]fluoride or no-carrier-added radioactive [18F]fluoride was added to the reaction mixture to form the fluorinated or radiofluorinated product.
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Affiliation(s)
- Mehrdad Balandeh
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA
| | - Alejandra Rios
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA.,Physics and Biology in Medicine Interdepartmental Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
| | - Nathanael Allison
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA
| | - Daniela Shirazi
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA
| | - Adrian Gomez
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA.,Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
| | - Laura Rambaran
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA
| | - Travis Holloway
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA
| | - Saman Sadeghi
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA
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Enhancement of surface stability of lithium manganese oxide spinel by silyl-group functionalized fluoride-responsive ionic liquid additives. J IND ENG CHEM 2018. [DOI: 10.1016/j.jiec.2018.03.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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