1
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Patra T, Arepally S, Seitz J, Wirth T. Electrocatalytic continuous flow chlorinations with iodine(I/III) mediators. Nat Commun 2024; 15:6329. [PMID: 39068163 PMCID: PMC11283512 DOI: 10.1038/s41467-024-50643-z] [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: 03/22/2024] [Accepted: 07/17/2024] [Indexed: 07/30/2024] Open
Abstract
Electrochemistry offers tunable, cost effective and environmentally friendly alternatives to carry out redox reactions with electrons as traceless reagents. The use of organoiodine compounds as electrocatalysts is largely underdeveloped, despite their widespread application as powerful and versatile reagents. Mechanistic data reveal that the hexafluoroisopropanol assisted iodoarene oxidation is followed by a stepwise chloride ligand exchange for the catalytic generation of the dichloroiodoarene mediator. Here, we report an environmentally benign iodine(I/III) electrocatalytic platform for the in situ generation of dichloroiodoarenes for different reactions such as mono- and dichlorinations as well as chlorocyclisations within a continuous flow setup.
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Affiliation(s)
- Tuhin Patra
- School of Chemistry, Cardiff University, Park Place, Main Building, Cardiff, Cymru/Wales, UK
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Argul, Odisha, India
| | - Sagar Arepally
- School of Chemistry, Cardiff University, Park Place, Main Building, Cardiff, Cymru/Wales, UK
| | - Jakob Seitz
- School of Chemistry, Cardiff University, Park Place, Main Building, Cardiff, Cymru/Wales, UK
| | - Thomas Wirth
- School of Chemistry, Cardiff University, Park Place, Main Building, Cardiff, Cymru/Wales, UK.
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2
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Atkins AP, Dean AC, Lennox AJJ. Benzylic C(sp 3)-H fluorination. Beilstein J Org Chem 2024; 20:1527-1547. [PMID: 39015617 PMCID: PMC11250007 DOI: 10.3762/bjoc.20.137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 06/26/2024] [Indexed: 07/18/2024] Open
Abstract
The selective fluorination of C(sp3)-H bonds is an attractive target, particularly for pharmaceutical and agrochemical applications. Consequently, over recent years much attention has been focused on C(sp3)-H fluorination, and several methods that are selective for benzylic C-H bonds have been reported. These protocols operate via several distinct mechanistic pathways and involve a variety of fluorine sources with distinct reactivity profiles. This review aims to give context to these transformations and strategies, highlighting the different tactics to achieve fluorination of benzylic C-H bonds.
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Affiliation(s)
| | - Alice C Dean
- University of Bristol, School of Chemistry, Bristol, BS8 1TS, U.K.
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3
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Bennett JJ, Murphy PV. Flow Chemistry for Synthesis of 2-(C-Glycosyl)acetates from Pyranoses via Tandem Wittig and Michael Reactions. Org Process Res Dev 2024; 28:1848-1859. [PMID: 38783857 PMCID: PMC11110061 DOI: 10.1021/acs.oprd.3c00414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/01/2024] [Accepted: 02/07/2024] [Indexed: 05/25/2024]
Abstract
C-Glycosyl compounds (C-glycosides) are a class of saccharide derivatives with improved stability over their O-linked counterparts. This paper reports the synthesis of several trans-2-(C-glycosyl)acetates via a tandem Wittig-Michael reaction from pyranoses (cyclic hemiacetals) using continuous flow processing, which gave improvements compared to reactions conducted in round-bottom flasks. Products were isolated in yields of >60% from reactions of benzyl-protected xylopyranoses, glucopyranoses, and galactopyranoses at higher temperatures and pressures, which were superior to yields from batch procedures. A two-step procedure involving the Wittig reaction followed by Michael reaction (intramolecular oxa-Michael) of the unsaturated ester obtained in the presence of DBU was developed. Reactions of protected mannopyranose gave low yields in corresponding reactions in flow due to competing C-2 epimerization.
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Affiliation(s)
- Jack J. Bennett
- School
of Biological and Chemical Sciences, University
of Galway, University Road, Galway H91 TK33, Ireland
| | - Paul V. Murphy
- School
of Biological and Chemical Sciences, University
of Galway, University Road, Galway H91 TK33, Ireland
- SSPC
− SFI Research Centre for Pharmaceuticals, University of Galway, University Road, Galway H91 TK33, Ireland
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4
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Kitamura T, Oyamada J, Higashi M, Kishikawa Y. Molecular Iodine as a Catalyst for Alkene Difluorination. J Org Chem 2024; 89:5896-5900. [PMID: 38593206 DOI: 10.1021/acs.joc.4c00179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
The difluorination reaction of alkenes catalyzed by molecular iodine was revealed for the first time. This difluorination reaction affords a simple and practical experimental method and can be applied to many aliphatic and aromatic alkenes bearing synthetically useful functional groups, such as ester, amide, hydroxy, and aryl groups. Preliminary mechanistic studies of this alkene difluorination suggest the existence of two catalytic cycles: the IF-driven cycle and the catalytic cycle by the IF adduct.
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Affiliation(s)
- Tsugio Kitamura
- Department of Chemistry and Applied Chemistry, Saga University, Saga 840-8502, Japan
| | - Juzo Oyamada
- Department of Chemistry and Applied Chemistry, Saga University, Saga 840-8502, Japan
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5
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Martins GM, Braga FC, de Castro PP, Brocksom TJ, de Oliveira KT. Continuous flow reactions in the preparation of active pharmaceutical ingredients and fine chemicals. Chem Commun (Camb) 2024; 60:3226-3239. [PMID: 38441166 DOI: 10.1039/d4cc00418c] [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: 03/20/2024]
Abstract
Herein, we present an overview of continuous flow chemistry, including photoflow and electroflow technologies in the preparation of active pharmaceutical ingredients (APIs) and fine chemical intermediates. Examples highlighting the benefits and challenges associated with continuous flow processes, mainly involving continuous thermal, photo- and electrochemical transformations, are drawn from the relevant literature, especially our experience and collaborations in this area, with emphasis on the synthesis and prospective scale-up.
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Affiliation(s)
- Guilherme M Martins
- Department of Chemistry, Federal University of São Carlos, São Carlos, São Paulo, 13565-905, Brazil.
| | - Felipe C Braga
- Department of Chemistry, Federal University of São Carlos, São Carlos, São Paulo, 13565-905, Brazil.
| | - Pedro P de Castro
- Department of Chemistry, Federal University of São Carlos, São Carlos, São Paulo, 13565-905, Brazil.
| | - Timothy J Brocksom
- Department of Chemistry, Federal University of São Carlos, São Carlos, São Paulo, 13565-905, Brazil.
| | - Kleber T de Oliveira
- Department of Chemistry, Federal University of São Carlos, São Carlos, São Paulo, 13565-905, Brazil.
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6
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Liu C, Liu Y, Yang S, Zheng B, Zhang Y. Electrochemical Lactonization Enabled by Unusual Shono-Type Oxidation from Functionalized Benzoic Acids. Org Lett 2024; 26:1936-1940. [PMID: 38407049 DOI: 10.1021/acs.orglett.4c00318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
A novel method for electrochemical lactonization via C(sp3)-H functionalization was developed. This metal- and oxidant-free strategy enabled the efficient synthesis of various lactones. Gram-scale reaction and derivatization of the lactone product demonstrated the synthetic utility of this methodology. Mechanistic studies using control experiments and CV curves elucidated the proposed intramolecular HAT and the oxidative cyclization pathway. An unusual Shono-type oxidation was realized through this electrochemical approach, proceeding without a traditional nucleophilic addition process.
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Affiliation(s)
- Chen Liu
- College of Science, China Agricultural University, Beijing 100193, P. R. China
| | - Yunge Liu
- College of Science, China Agricultural University, Beijing 100193, P. R. China
| | - Shurui Yang
- College of Science, China Agricultural University, Beijing 100193, P. R. China
| | - Bing Zheng
- College of Science, China Agricultural University, Beijing 100193, P. R. China
| | - Yunfei Zhang
- College of Science, China Agricultural University, Beijing 100193, P. R. China
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7
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Kim J, Kim C, Lee D. Fluoride-triggered phase transition of metallogels for on-demand in situ containment of fluids. Chem Commun (Camb) 2024; 60:1762-1765. [PMID: 38251973 DOI: 10.1039/d3cc06023c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
Sol-gel transition regulates mass transport in fluidic systems. We designed pre-gelators that react with fluoride anions to form a metallogel barrier. A combination of spectroscopic, rheological, and X-ray spectroscopic studies elucidated the mechanism of gelation involving desilylation followed by metal coordination-driven self-assembly, the kinetics of which can be finely controlled by the chemical structure of the silyl substituents. Protonation-induced degelation restores flow, allowing the metallogel to function as a reversible chemical valve.
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Affiliation(s)
- Junghwan Kim
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
- Carbon Composite Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology (KIST), Wanju 55324, Korea
| | - Chungryeol Kim
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
| | - Dongwhan Lee
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
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8
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Moskalik MY. Monofluoromethylation of N-Heterocyclic Compounds. Int J Mol Sci 2023; 24:17593. [PMID: 38139426 PMCID: PMC10744182 DOI: 10.3390/ijms242417593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 12/24/2023] Open
Abstract
The review focuses on recent advances in the methodologies for the formation or introduction of the CH2F moiety in N-heterocyclic substrates over the past 5 years. The monofluoromethyl group is one of the most versatile fluorinated groups used to modify the properties of molecules in synthetic medical chemistry. The review summarizes two strategies for the monofluoromethylation of N-containing heterocycles: direct monofluoromethylation with simple XCH2F sources (for example, ICH2F) and the assembly of N-heterocyclic structures from CH2F-containing substrates. The review describes the monofluoromethylation of pharmaceutically important three-, five- and six-membered N-heterocycles: pyrrolidines, pyrroles, indoles, imidazoles, triazoles, benzothiazoles, carbazoles, indazoles, pyrazoles, oxazoles, piperidines, morpholines, pyridines, quinolines and pyridazines. Assembling of 6-fluoromethylphenanthridine, 5-fluoromethyl-2-oxazolines, C5-monofluorinated isoxazoline N-oxides, and α-fluoromethyl-α-trifluoromethylaziridines is also shown. Fluoriodo-, fluorchloro- and fluorbromomethane, FCH2SO2Cl, monofluoromethyl(aryl)sulfoniummethylides, monofluoromethyl sulfides, (fluoromethyl)triphenylphosphonium iodide and 2-fluoroacetic acid are the main fluoromethylating reagents in recent works. The replacement of atoms and entire functional groups with a fluorine atom(s) leads to a change and often improvement in activity, chemical or biostability, and pharmacokinetic properties. The monofluoromethyl group is a bioisoster of -CH3, -CH2OH, -CH2NH2, -CH2CH3, -CH2NO2 and -CH2SH moieties. Bioisosteric replacement with the CH2F group is both an interesting task for organic synthesis and a pathway to modify drugs, agrochemicals and useful intermediates.
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Affiliation(s)
- Mikhail Yu Moskalik
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Division of the Russian Academy of Sciences, 1 Favorsky Street, 664033 Irkutsk, Russia
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9
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Yu J, Liu T, Sun W, Zhang Y. Electrochemical Decarboxylative Elimination of Carboxylic Acids to Alkenes. Org Lett 2023; 25:7816-7821. [PMID: 37870311 DOI: 10.1021/acs.orglett.3c02997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
An electrochemical strategy for the decarboxylative elimination of carboxylic acids to alkenes at room temperature has been developed. This mild and oxidant-free method provides a green alternative to traditional thermal decarboxylation reactions. Structurally diverse aliphatic carboxylic acids, including biologically active drugs, underwent smooth conversion to the corresponding alkenes in good to excellent yields.
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Affiliation(s)
- Jiage Yu
- College of Science, China Agricultural University, Beijing 100193, P. R. China
| | - Teng Liu
- College of Science, China Agricultural University, Beijing 100193, P. R. China
| | - Wanhao Sun
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100871, P. R. China
| | - Yunfei Zhang
- College of Science, China Agricultural University, Beijing 100193, P. R. China
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10
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Lee TC, Tong Y, Fu WC. Advances in Continuous Flow Fluorination Reactions. Chem Asian J 2023; 18:e202300723. [PMID: 37707985 DOI: 10.1002/asia.202300723] [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: 08/17/2023] [Revised: 09/12/2023] [Accepted: 09/14/2023] [Indexed: 09/16/2023]
Abstract
Fluorination reactions are important in constructing organofluorine motifs, which contribute to favorable biological properties in pharmaceuticals and agrochemicals. However, fluorination reagents and reactions are associated with various problems, such as their hazardous nature, high exothermicity, and poor selectivity and scalability. Continuous flow has emerged as a transformative technology to provide many advantages relative to batch syntheses. This review article summarizes recent continuous flow techniques that address the limitations and challenges of fluorination reactions. Approaches based on different flow techniques are discussed, including gas-liquid reactions, packed-bed reactors, in-line purifications, streamlined multistep synthesis, large-scale reactions well as flow photoredox- and electrocatalysis.
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Affiliation(s)
- Tsz Chun Lee
- Department of Chemistry, City University of Hong Kong, Tat Chee Ave, Kowloon, Hong Kong SAR, China
| | - Yi Tong
- Department of Chemistry, City University of Hong Kong, Tat Chee Ave, Kowloon, Hong Kong SAR, China
| | - Wai Chung Fu
- Department of Chemistry, City University of Hong Kong, Tat Chee Ave, Kowloon, Hong Kong SAR, China
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11
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Chen SJ, Zhong WQ, Huang JM. Electrochemical Trifluoromethylation and Sulfonylation of N-Allylamides: Synthesis of Oxazoline Derivatives. J Org Chem 2023; 88:12630-12640. [PMID: 37579302 DOI: 10.1021/acs.joc.3c01310] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
We report a new method for the synthesis of trifluoromethylated and sulfonylated oxazolines by electrochemical radical cascade cyclizations of N-allylamides with sodium trifluoromethanesulfinate or sulfonylhydrazines. This protocol provides a green and useful strategy to synthesize trifluoromethylated and sulfonylated oxazolines with a broad substrate scope under ambient conditions.
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Affiliation(s)
- Shu-Jun Chen
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, People's Republic of China
| | - Wei-Qiang Zhong
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, People's Republic of China
| | - Jing-Mei Huang
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, People's Republic of China
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12
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Burke A, Di Filippo M, Spiccio S, Schito AM, Caviglia D, Brullo C, Baumann M. Antimicrobial Evaluation of New Pyrazoles, Indazoles and Pyrazolines Prepared in Continuous Flow Mode. Int J Mol Sci 2023; 24:ijms24065319. [PMID: 36982392 PMCID: PMC10048858 DOI: 10.3390/ijms24065319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 03/03/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
Multi-drug resistant bacterial strains (MDR) have become an increasing challenge to our health system, resulting in multiple classical antibiotics being clinically inactive today. As the de-novo development of effective antibiotics is a very costly and time-consuming process, alternative strategies such as the screening of natural and synthetic compound libraries is a simple approach towards finding new lead compounds. We thus report on the antimicrobial evaluation of a small collection of fourteen drug-like compounds featuring indazoles, pyrazoles and pyrazolines as key heterocyclic moieties whose synthesis was achieved in continuous flow mode. It was found that several compounds possessed significant antibacterial potency against clinical and MDR strains of the Staphylococcus and Enterococcus genera, with the lead compound (9) reaching MIC values of 4 µg/mL on those species. In addition, time killing experiments performed on compound 9 on Staphylococcus aureus MDR strains highlight its activity as bacteriostatic. Additional evaluations regarding the physiochemical and pharmacokinetic properties of the most active compounds are reported and showcased, promising drug-likeness, which warrants further explorations of the newly identified antimicrobial lead compound.
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Affiliation(s)
- Adam Burke
- Science Centre South, School of Chemistry, University College Dublin, Dublin 4, Ireland
| | - Mara Di Filippo
- Science Centre South, School of Chemistry, University College Dublin, Dublin 4, Ireland
| | - Silvia Spiccio
- Science Centre South, School of Chemistry, University College Dublin, Dublin 4, Ireland
| | - Anna Maria Schito
- Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa, 16132 Genoa, Italy
| | - Debora Caviglia
- Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa, 16132 Genoa, Italy
- Section of Medicinal Chemistry, Department of Pharmacy (DIFAR), University of Genoa, 16132 Genoa, Italy
| | - Chiara Brullo
- Section of Medicinal Chemistry, Department of Pharmacy (DIFAR), University of Genoa, 16132 Genoa, Italy
| | - Marcus Baumann
- Science Centre South, School of Chemistry, University College Dublin, Dublin 4, Ireland
- Correspondence:
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13
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Leech MC, Nagornîi D, Walsh JM, Kiaku C, Poole DL, Mason J, Goodall ICA, Devo P, Lam K. eFluorination Using Cheap and Readily Available Tetrafluoroborate Salts. Org Lett 2023; 25:1353-1358. [PMID: 36856464 DOI: 10.1021/acs.orglett.2c04305] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
A practical electrochemical method for the rapid, safer, and mild synthesis of tertiary hindered alkyl fluorides from carboxylic acids has been developed without the need for hydrofluoric acid salts or non-glass reactors. In this anodic fluorination, collidinium tetrafluoroborate acts as both the supporting electrolyte and fluoride donor. A wide range of functional groups has been shown to be compatible, and the possibility of scale-up using flow electrochemistry has also been demonstrated.
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Affiliation(s)
- Matthew C Leech
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, United Kingdom
| | - Dmitrii Nagornîi
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, United Kingdom
| | - Jamie M Walsh
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, United Kingdom
| | - Cyrille Kiaku
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, United Kingdom
| | - Darren L Poole
- Discovery High-Throughput Chemistry, Medicinal Chemistry, GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, United Kingdom
| | - Joseph Mason
- Discovery High-Throughput Chemistry, Medicinal Chemistry, GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, United Kingdom
| | - Iain C A Goodall
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, United Kingdom
| | - Perry Devo
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, United Kingdom
| | - Kevin Lam
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, United Kingdom
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14
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Spils J, Wirth T, Nachtsheim BJ. Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation. Beilstein J Org Chem 2023; 19:27-32. [PMID: 36686040 PMCID: PMC9830492 DOI: 10.3762/bjoc.19.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 12/07/2022] [Indexed: 01/04/2023] Open
Abstract
We describe a multi-step continuous-flow procedure for the generation of six-membered diaryliodonium salts. The accompanying scalability and atom economy are significant improvements to existing batch methods. Benzyl acetates are submitted to this two-step procedure as highly available and cheap starting materials. An acid-catalyzed Friedel-Crafts alkylation followed by an anodic oxidative cyclization yielded a defined set of cyclic iodonium salts in a highly substrate-dependent yield.
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Affiliation(s)
- Julian Spils
- Institute for Organic and Analytical Chemistry, University of Bremen, Leobener Straße 7, 28359 Bremen, Germany
| | - Thomas Wirth
- School of Chemistry, Cardiff University, Park Place, Main Building, Cardiff CF10 3AT, UK
| | - Boris J Nachtsheim
- Institute for Organic and Analytical Chemistry, University of Bremen, Leobener Straße 7, 28359 Bremen, Germany
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15
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Jiang Y, Yorimitsu H. Taming Highly Unstable Radical Anions and 1,4-Organodilithiums by Flow Microreactors: Controlled Reductive Dimerization of Styrenes. JACS AU 2022; 2:2514-2521. [PMID: 36465543 PMCID: PMC9709950 DOI: 10.1021/jacsau.2c00375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/05/2022] [Accepted: 10/05/2022] [Indexed: 05/21/2023]
Abstract
The reduction of styrenes with lithium arenide in a flow microreactor leads to the instantaneous generation of highly unstable radical anions that subsequently dimerize to yield the corresponding 1,4-organodilithiums. A flow reactor with fast mixing is essential for this reductive dimerization as the efficiency and selectivity are low under batch conditions. A series of styrenes undergo dimerization, and the resulting 1,4-organodilithiums are trapped with various electrophiles. Trapping with divalent electrophiles affords precursors for useful yet less accessible cyclic structures, for example, siloles from dichlorosilanes. Thus, we highlight the power of single-electron reduction of unsaturated compounds in flow microreactors for organic synthesis.
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16
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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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17
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Bajada MA, Sanjosé-Orduna J, Di Liberto G, Tosoni S, Pacchioni G, Noël T, Vilé G. Interfacing single-atom catalysis with continuous-flow organic electrosynthesis. Chem Soc Rev 2022; 51:3898-3925. [PMID: 35481480 DOI: 10.1039/d2cs00100d] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The global warming crisis has sparked a series of environmentally cautious trends in chemistry, allowing us to rethink the way we conduct our synthesis, and to incorporate more earth-abundant materials in our catalyst design. "Single-atom catalysis" has recently appeared on the catalytic spectrum, and has truly merged the benefits that homogeneous and heterogeneous analogues have to offer. Further still, the possibility to activate these catalysts by means of a suitable electric potential could pave the way for a true integration of diverse synthetic methodologies and renewable electricity. Despite their esteemed benefits, single-atom electrocatalysts are still limited to the energy sector (hydrogen evolution reaction, oxygen reduction, etc.) and numerous examples in the literature still invoke the use of precious metals (Pd, Pt, Ir, etc.). Additionally, batch electroreactors are employed, which limit the intensification of such processes. It is of paramount importance that the field continues to grow in a more sustainable direction, seeking new ventures into the space of organic electrosynthesis and flow electroreactor technologies. In this piece, we discuss some of the progress being made with earth abundant homogeneous and heterogeneous electrocatalysts and flow electrochemistry, within the context of organic electrosynthesis, and highlight the prospects of alternatively utilizing single-atom catalysts for such applications.
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Affiliation(s)
- Mark A Bajada
- Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
| | - Jesús Sanjosé-Orduna
- Flow Chemistry Group, van't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Giovanni Di Liberto
- Department of Materials Science, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, Italy
| | - Sergio Tosoni
- Department of Materials Science, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, Italy
| | - Gianfranco Pacchioni
- Department of Materials Science, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, Italy
| | - Timothy Noël
- Flow Chemistry Group, van't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Gianvito Vilé
- Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
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18
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Chen C, Wang X, Yang T. Recent Updates on Electrogenerated Hypervalent Iodine Derivatives and Their Applications as Mediators in Organic Electrosynthesis. Front Chem 2022; 10:883474. [PMID: 35494647 PMCID: PMC9043554 DOI: 10.3389/fchem.2022.883474] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 03/25/2022] [Indexed: 01/15/2023] Open
Abstract
With the renaissance of chemical electrosynthesis in the last decade, the electrochemistry of hypervalent iodine compounds has picked up the pace and achieved significant improvements. By employing traceless electrons instead of stoichiometric oxidants as the alternative clean “reagents”, many hypervalent iodine compounds were efficiently electro-synthesized via anodic oxidation methods and utilized as powerful redox mediators triggering valuable oxidative coupling reactions in a more sustainable way. This minireview gives an up-to-date overview of the recent advances during the past 3 years, encompassing enhanced electrosynthesis technologies, novel synthetic applications, and ideas for improving reaction sustainability.
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Affiliation(s)
- Chaoyue Chen
- School of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou, China
- *Correspondence: Chaoyue Chen, ; Tinghai Yang,
| | - Xin Wang
- School of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou, China
| | - Tinghai Yang
- School of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou, China
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China
- *Correspondence: Chaoyue Chen, ; Tinghai Yang,
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19
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Electrochemical intramolecular haloheterocyclization reactions using 1,2-dihaloethanes as halogenating reagents. Tetrahedron Lett 2022. [DOI: 10.1016/j.tetlet.2021.153602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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He Y, Yin Y, Liu C, Wu XF, Yin Z. Electrochemical oxidative cyclization of N-allylcarboxamides: efficient synthesis of halogenated oxazolines. NEW J CHEM 2022. [DOI: 10.1039/d1nj04819h] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Herein, we reported an efficient and sustainable intramolecular electrochemical cyclization of N-allylcarboxamides for the synthesis of various halogenated oxazolines.
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Affiliation(s)
- Yanyang He
- School of Pharmacy, Jiangsu University, Zhenjiang 212013, P. R. China
| | - Yanzhao Yin
- School of Pharmacy, Jiangsu University, Zhenjiang 212013, P. R. China
| | - Chenwei Liu
- School of Pharmacy, Jiangsu University, Zhenjiang 212013, P. R. China
| | - Xiao-Feng Wu
- Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Science, 116023 Dalian, Liaoning, China
- Leibniz-Institut für Katalyse e. V., Albert-Einstein-Straße 29a, 18059 Rostock, Germany
| | - Zhiping Yin
- School of Pharmacy, Jiangsu University, Zhenjiang 212013, P. R. China
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21
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Doobary S, Poole DL, Lennox AJJ. Intramolecular Alkene Fluoroarylation of Phenolic Ethers Enabled by Electrochemically Generated Iodane. J Org Chem 2021; 86:16095-16103. [PMID: 34766770 DOI: 10.1021/acs.joc.1c01946] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The 3-substituted chromane core is found in several bioactive natural products. Herein, we describe a route to 3-fluorinated chromanes from allylic phenol ethers. Our external oxidant-free approach takes advantage of an electrochemical generation of a hypervalent iodine species, difluoro-λ3-tolyl iodane, which mediates the alkene fluoroarylation. High yields and selectivity for this transformation are achieved for electron poor substrates. The redox chemistry has been characterized for the electrochemical generation of the iodane in the presence of fluoride, and insights into the mechanism are given. The transformation has been demonstrated on gram scales, which indicates the potential broader utility of the process.
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Affiliation(s)
- Sayad Doobary
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Darren L Poole
- Medicines Design, GSK Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, U.K
| | - Alastair J J Lennox
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
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