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Claraz A. Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations. Beilstein J Org Chem 2024; 20:1988-2004. [PMID: 39161708 PMCID: PMC11331547 DOI: 10.3762/bjoc.20.175] [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: 04/14/2024] [Accepted: 07/23/2024] [Indexed: 08/21/2024] Open
Abstract
Hydrazones are important structural motifs in organic synthesis, providing a useful molecular platform for the construction of valuable compounds. Electrooxidative transformations of hydrazones constitute an attractive opportunity to take advantage of the versatility of these reagents. By directly harnessing the electrical current to perform the oxidative process, a large panel of organic molecules can be accessed from readily available hydrazones under mild, safe and oxidant-free reaction conditions. This review presents a comprehensive overview of oxidative electrosynthetic transformations of hydrazones. It includes the construction of azacycles, the C(sp2)-H functionalization of aldehyde-derived hydrazones and the access to diazo compounds as either synthetic intermediates or products. A special attention is paid to the reaction mechanism with the aim to encourage further development in this field.
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Affiliation(s)
- Aurélie Claraz
- Institut de Chimie des Substances Naturelles, CNRS, Univ. Paris-Saclay, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France
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2
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Zhou Y, Akkarasereenon K, Liu L, Lin R, Song L, Tong R. Ecofriendly Protocol for ipso-Bromination of Arylboronic Acids. Org Lett 2024; 26:5151-5156. [PMID: 38864512 DOI: 10.1021/acs.orglett.4c01570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
We report a novel and environmentally friendly method for the ipso-bromination of arylboronic acids by exploiting the oxone/KBr system. We discovered that CuBr can catalyze the reaction and increase the yield from 63 to 97%. We believe that CuBr might catalyze the in situ generation of HOBr from oxone/KBr. The mild reaction condition permits tolerance of a diverse array of functional groups with exclusive regio- and chemoselectivity and allows low-cost large-scale reaction without explosion risk.
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Affiliation(s)
- Yiqin Zhou
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China
| | - Kornkamon Akkarasereenon
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China
| | - Lifang Liu
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Ran Lin
- College of Bee Science and Biomedicine, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Liyan Song
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Rongbiao Tong
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China
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Henry M, Minty L, Kwok ACW, Elwood JML, Foulis AJ, Pettinger J, Jamieson C. One-Pot Oxidative Amidation of Aldehydes via the Generation of Nitrile Imine Intermediates. J Org Chem 2024; 89:7913-7926. [PMID: 38778786 PMCID: PMC11165588 DOI: 10.1021/acs.joc.4c00575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/22/2024] [Accepted: 05/16/2024] [Indexed: 05/25/2024]
Abstract
A one-pot procedure for the oxidative amidation of aldehydes via the in situ generation of reactive nitrile imine (NI) intermediates has been developed. Distinct from our progenitor processes, mechanistic and control experiments revealed that the NI undergoes rapid oxidation to an acyl diazene species, which then facilitates N-acylation of an amine. A range of substrates have been explored, including application in the synthesis of pharmaceutically relevant compounds.
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Affiliation(s)
- Martyn
C. Henry
- Department
of Pure and Applied Chemistry, University
of Strathclyde, Glasgow G1 1XL, United
Kingdom
| | - Laura Minty
- Department
of Pure and Applied Chemistry, University
of Strathclyde, Glasgow G1 1XL, United
Kingdom
| | - Alexander C. W. Kwok
- Department
of Pure and Applied Chemistry, University
of Strathclyde, Glasgow G1 1XL, United
Kingdom
| | - Jessica M. L. Elwood
- Department
of Pure and Applied Chemistry, University
of Strathclyde, Glasgow G1 1XL, United
Kingdom
| | - Adam J. Foulis
- Department
of Pure and Applied Chemistry, University
of Strathclyde, Glasgow G1 1XL, United
Kingdom
| | - Jonathan Pettinger
- GSK,
Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom
| | - Craig Jamieson
- Department
of Pure and Applied Chemistry, University
of Strathclyde, Glasgow G1 1XL, United
Kingdom
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Noël F, El Kaïm L, Masson G, Claraz A. Electrocatalytic dehydrogenative and defluorinative coupling between aldehyde-derived N, N-dialkylhydrazones and fluoromalonates: synthesis of 2-pyrazolines. Org Biomol Chem 2024; 22:4269-4273. [PMID: 38742988 DOI: 10.1039/d4ob00588k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
An electrocatalytic synthesis of 2-pyrazolines via dehydrogenative and defluorinative cross-coupling reactions between (hetero)arylaldehyde-derived N,N-dialkylhydrazones and fluoromalonates is disclosed. Salient features of this work include (i) readily available starting materials, (ii) practical reaction conditions, and (ii) a formal oxidative (4 + 1)-cycloaddition via triple C-H bond functionalization. Cyclic voltammetry analyses support the electrocatalytic formation of an α-fluoromalonyl radical.
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Affiliation(s)
- Florent Noël
- Institut de Chimie des Substances Naturelles, CNRS, Univ. Paris-Saclay, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
| | - Laurent El Kaïm
- Laboratoire de Synthèse Organique (LSO-UMR 76523), CNRS, Ecole Polytechnique, ENSTA-Paris, Institut Polytechnique de Paris, 828 Bd des Maréchaux, 91128 Palaiseau Cedex, France
| | - Géraldine Masson
- Institut de Chimie des Substances Naturelles, CNRS, Univ. Paris-Saclay, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
- HitCat, Seqens-CNRS Joint Laboratory, Seqens'Lab, Porcheville, France
| | - Aurélie Claraz
- Institut de Chimie des Substances Naturelles, CNRS, Univ. Paris-Saclay, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
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Zhao T, Sun Y, Meng Y, Liu L, Dai J, Yan G, Pan X, Guan X, Song L, Lin R. Design, Synthesis and Antifungal Activities of Novel Pyrazole Analogues Containing the Aryl Trifluoromethoxy Group. Molecules 2023; 28:6279. [PMID: 37687108 PMCID: PMC10488855 DOI: 10.3390/molecules28176279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 08/18/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023] Open
Abstract
On the basis of the three-component synthetic methodology developed by us, a total of twenty-six pyrazole compounds bearing aryl OCF3 were designed and synthesized. Their chemical structures were characterized by 1H and 13C nuclear magnetic resonance and high-resolution mass spectrometry. These compounds were evaluated systematically for antifungal activities in vitro against six plant pathogenic fungi by the mycelium growth rate method. Most of the compounds showed some activity against each of the fungi at 100 μg/mL. Compounds 1t and 1v exhibited higher activity against all the tested fungi, and 1v displayed the highest activity against F. graminearum with an EC50 value of 0.0530 μM, which was comparable with commercial pyraclostrobin. Structure-activity relationship analysis showed that, with respect to the R1 substituent, the straight chain or cycloalkyl ring moiety was a key structural moiety for the activity, and the R2 substituent on the pyrazole ring could have significant effects on the activity. Simple and readily available pyrazoles with potent antifungal activity were obtained, which are ready for further elaboration to serve as a pharmacophore in new potential antifungal agents.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Liyan Song
- Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China (G.Y.); (X.P.); (X.G.)
| | - Ran Lin
- Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China (G.Y.); (X.P.); (X.G.)
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Zheng T, Xu J, Cheng S, Ye J, Ma S, Tong R. Green Halogenation of Indoles with Oxone-Halide. J Org Chem 2023; 88:11497-11503. [PMID: 37499121 DOI: 10.1021/acs.joc.3c00638] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Oxidative functionalization of indoles is one of the most widely used approaches to exploit the synthetic utility of indoles. In continuation of our research interest in the green oxidation of indoles, we further explore the oxidation of indoles with oxone-halide and discover that the protecting group on the nitrogen of indoles plays a decisive role in controlling the pathways of indole oxidation with oxone-halide. An electron-withdrawing group on the nitrogen of indoles (N-EWG) enables C2 halogenation with stoichiometric halide, while C3 halogenation could be selectively achieved by using stoichiometric halide without dependence on the electronic property of the protecting group on the indole nitrogen. Different from our previous results obtained by using catalytic halide, these findings lead to the development of an environmentally friendly, efficient, and mild protocol for access to 2- or 3-haloindoles (chloro and bromo). As compared to the previous synthetic methods for 2-/3-haloindoles, our method exploits the in situ-generated reactive halogenating species from oxone-halide for halogenation of indoles and thus eliminates the use of stoichiometric halogenating agents and the production of toxic and hazardous organic byproducts derived from oxidants.
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Affiliation(s)
- Tao Zheng
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang 550025, China
| | - Jun Xu
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang 550025, China
| | - Shaojun Cheng
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang 550025, China
| | - Jianghai Ye
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang 550025, China
| | - Shiqiang Ma
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon 999077, Hong Kong, China
| | - Rongbiao Tong
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon 999077, Hong Kong, China
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Linden M, Hofmann S, Herman A, Ehler N, Bär RM, Waldvogel SR. Electrochemical Synthesis of Pyrazolines and Pyrazoles via [3+2] Dipolar Cycloaddition. Angew Chem Int Ed Engl 2023; 62:e202214820. [PMID: 36478106 DOI: 10.1002/anie.202214820] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 12/06/2022] [Accepted: 12/06/2022] [Indexed: 12/12/2022]
Abstract
Pyrazolines and pyrazoles are common and important motifs of pharmaceutical agents and agrochemicals. Herein, the first electrochemical approach for their direct synthesis from easily accessible hydrazones and dipolarophiles up to decagram scale is presented. The application of a biphasic system (aqueous/organic) even allows for the conversion of highly sensitive alkenes, wherein inexpensive sodium iodide is employed in a dual role as supporting electrolyte and mediator. In addition, mechanistic insight into the reaction is given by the isolation of key step intermediates. The relevance of the presented reaction is underlined by the synthesis of commercial herbicide safener mefenpyr-diethyl in good yields.
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Affiliation(s)
- Martin Linden
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Silja Hofmann
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Antonia Herman
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Nicole Ehler
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Robin M Bär
- Research & Development, Crop Science, Bayer AG, Alfred-Nobel-Str. 50, 40789, Monheim am Rhein, Germany
| | - Siegfried R Waldvogel
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
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Song L, Zhou Y, Liang H, Li H, Lai Y, Yao H, Lin R, Tong R. Two Green Protocols for Halogenative Semipinacol Rearrangement. J Org Chem 2023; 88:504-512. [PMID: 36480595 DOI: 10.1021/acs.joc.2c02496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Semipinacol rearrangement is a special type of Wagner-Meerwein rearrangement that involves carbocation 1,2-rearrangement to provide carbonyl compounds with an α-quaternary carbon center. It has been strategically used for natural product synthesis and construction of highly congested quaternary carbons. Herein, we report a safe and green protocol that uses oxone/halide and Fenton bromide to achieve halogenative semipinacol rearrangement. The key feature of this method is the green in situ generation of reactive halogenating species from oxidation of halide with oxone or H2O2, which produces a nontoxic byproduct (potassium sulfate or water). Easy operation (insensitive to air and moisture) at room temperature without using special equipment adds additional advantage over previous methods.
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Affiliation(s)
- Liyan Song
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Yiqin Zhou
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China
| | - Hanbin Liang
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China
| | - Hongzuo Li
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Yunrong Lai
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Hongliang Yao
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, Guangdong 510275, China
| | - Ran Lin
- Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Rongbiao Tong
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China.,Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, Guangdong 510275, China
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Liang L, Guo LD, Tong R. Achmatowicz Rearrangement-Inspired Development of Green Chemistry, Organic Methodology, and Total Synthesis of Natural Products. Acc Chem Res 2022; 55:2326-2340. [PMID: 35916456 DOI: 10.1021/acs.accounts.2c00358] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The six-membered heterocycles containing oxygen and nitrogen (tetrahydropyrans, pyrans, piperidines) are among the most common heterocyclic structures ubiquitously present in bioactive molecules such as carbohydrates, small-molecule drugs, and natural products. Chemical synthesis of fully functionalized pyrans and piperidines is a research theme of practical importance and scientific significance and, thus, has attracted continuous interest from synthetic chemists. Among the numerous synthetic approaches, Achmatowicz rearrangement (AchR) represents a general and unique strategy that uses biomass-derived furfuryl alcohols as the renewable starting material to obtain fully functionalized six-membered oxygen/nitrogen heterocycles, which provides golden opportunities for organic chemists to address various synthetic challenges.This Account summarizes our 10 years of work on exploiting AchR to address some challenges in organic synthesis ranging from green chemistry and organic methodology to the total synthesis of natural products. We enabled the sustainable and safe use of AchR in a small (academia) or large (industrial) scale by developing two generations of green approaches for AchR (oxone-halide and Fenton-halide), which largely eliminate the use of the most popular, but more toxic and expansive, NBS and m-CPBA. This triggered our intensive interest in developing new green chemistry for important organic reactions, in particular, halogenation/oxidation reactions involving reactive halogenating species with the aim of eliminating the use of commonly used toxic halogen agents such as elemental bromine, chlorine gas, and various N-haloamide reagents (NBS, NCS, and NIS). We successfully employed oxone-halide and Fenton-halide as green alternatives to several mechanistically related organic reactions including arene/alkene halogenation, oxidation or oxidative rearrangement of indoles, oxidation of alcohols/thioacetals, and oxidative halogenation of aldoximes for the in situ generation of nitrile oxide. These green reactions are expected to have a solid impact on the future of organic synthesis in academia and industries.We expanded the synthetic utility of AchR by exploring several new transformations of AchR products and developed a cascade reductive ring expansion, reductive deoxygenation/Heck-Matsuda arylation, palladium-catalyzed C-arylation, and regiodivergent [3 + 2] cycloaddition with 1,3-dicarbonyls. These methodologies offer a new avenue to fully functionalized six-membered heterocycles.The synthetic utility of AchR was demonstrated in our total synthesis of 28 natural products with a pyran/piperidine moiety. The AchR-based strategy endows the total synthesis with scalability, sustainability, and flexibility. The green and scalable approaches developed in our lab for AchR allow us to easily obtain decagrams of synthetically valuable pyrans and/or piperidines with low risk and low cost from biomass-derived furfuryl alcohol/aldehyde.
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