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Carson MC, Liu CR, Kozlowski MC. Synthesis of Phenol-Pyridinium Salts Enabled by Tandem Electron Donor-Acceptor Complexation and Iridium Photocatalysis. J Org Chem 2024; 89:3419-3429. [PMID: 38365194 PMCID: PMC11197922 DOI: 10.1021/acs.joc.3c02872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2024]
Abstract
Herein, we describe a dual photocatalytic system to synthesize phenol-pyridinium salts using visible light. Utilizing both electron donor-acceptor (EDA) complex and iridium(III) photocatalytic cycles, the C-N cross-coupling of unprotected phenols and pyridines proceeds in the presence of oxygen to furnish pyridinium salts. Photocatalytic generation of phenoxyl radical cations also enabled a nucleophilic aromatic substitution (SNAr) of a fluorophenol with an electron-poor pyridine. Spectroscopic experiments were conducted to probe the mechanism and reaction selectivity. The unique reactivity of these phenol-pyridinium salts were displayed in several derivatization reactions, providing rapid access to a diverse chemical space.
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Affiliation(s)
- Matthew C. Carson
- Department of Chemistry, Roy and Diana Vagelos Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Cindy R. Liu
- Department of Chemistry, Roy and Diana Vagelos Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Marisa C. Kozlowski
- Department of Chemistry, Roy and Diana Vagelos Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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2
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Escolano M, Gaviña D, Alzuet-Piña G, Díaz-Oltra S, Sánchez-Roselló M, Pozo CD. Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines. Chem Rev 2024; 124:1122-1246. [PMID: 38166390 PMCID: PMC10902862 DOI: 10.1021/acs.chemrev.3c00625] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Dearomatization reactions have become fundamental chemical transformations in organic synthesis since they allow for the generation of three-dimensional complexity from two-dimensional precursors, bridging arene feedstocks with alicyclic structures. When those processes are applied to pyridines, quinolines, and isoquinolines, partially or fully saturated nitrogen heterocycles are formed, which are among the most significant structural components of pharmaceuticals and natural products. The inherent challenge of those transformations lies in the low reactivity of heteroaromatic substrates, which makes the dearomatization process thermodynamically unfavorable. Usually, connecting the dearomatization event to the irreversible formation of a strong C-C, C-H, or C-heteroatom bond compensates the energy required to disrupt the aromaticity. This aromaticity breakup normally results in a 1,2- or 1,4-functionalization of the heterocycle. Moreover, the combination of these dearomatization processes with subsequent transformations in tandem or stepwise protocols allows for multiple heterocycle functionalizations, giving access to complex molecular skeletons. The aim of this review, which covers the period from 2016 to 2022, is to update the state of the art of nucleophilic dearomatizations of pyridines, quinolines, and isoquinolines, showing the extraordinary ability of the dearomative methodology in organic synthesis and indicating their limitations and future trends.
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Affiliation(s)
- Marcos Escolano
- Department of Organic Chemistry, Faculty of Pharmacy, University of Valencia, 46100 Burjassot, Valencia, Spain
| | - Daniel Gaviña
- Department of Organic Chemistry, Faculty of Pharmacy, University of Valencia, 46100 Burjassot, Valencia, Spain
| | - Gloria Alzuet-Piña
- Department of Inorganic Chemistry, Faculty of Pharmacy, University of Valencia, 46100 Burjassot, Valencia, Spain
| | - Santiago Díaz-Oltra
- Department of Organic Chemistry, Faculty of Pharmacy, University of Valencia, 46100 Burjassot, Valencia, Spain
| | - María Sánchez-Roselló
- Department of Organic Chemistry, Faculty of Pharmacy, University of Valencia, 46100 Burjassot, Valencia, Spain
| | - Carlos Del Pozo
- Department of Organic Chemistry, Faculty of Pharmacy, University of Valencia, 46100 Burjassot, Valencia, Spain
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3
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Mondal SL, Bhajammanavar V, Ramakrishna I, Baidya M. Brønsted acid-catalyzed annulation reaction of hydroxamic acids: synthesis of cyclopentane-fused isoxazolidines and their benzilic amide rearrangement. Chem Commun (Camb) 2023; 59:13211-13214. [PMID: 37853763 DOI: 10.1039/d3cc03810f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
Readily available hydroxamic acids were leveraged to access challenging nitrones in the presence of H3PO4 as a Brønsted acid catalyst and engaged in an intramolecular (3+2) annulation reaction to make valuable cyclopentane-fused isoxazolidines with high yields and excellent diastereoselectivity. The products were further utilized in a unique base-promoted benzilic amide rearrangement to provide cyclopentane-fused γ-lactams bearing three contiguous stereocenters as a single diastereomer.
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Affiliation(s)
- Swati Lekha Mondal
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
| | - Vinod Bhajammanavar
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
| | - Isai Ramakrishna
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
| | - Mahiuddin Baidya
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
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4
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Harmange Magnani C, Hernández-Meléndez JR, Tantillo DJ, Maimone TJ. Total Synthesis of Altemicidin: A Surprise Ending for a Monoterpene Alkaloid. JACS AU 2023; 3:2883-2893. [PMID: 37885570 PMCID: PMC10598567 DOI: 10.1021/jacsau.3c00417] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/21/2023] [Accepted: 09/21/2023] [Indexed: 10/28/2023]
Abstract
Monoterpene alkaloids encompass distinct chemical diversity and wide-ranging bioactivity. Their compact complexity has made them popular as synthetic targets and has inspired many distinct strategies and tactics in the field of heterocyclic chemistry. This article documents the evolution of a synthetic program aimed at accessing the unusual sulfonamide-containing natural product altemicidin, which was generally believed to be a monoterpene alkaloid throughout our entire synthetic investigations but has recently been found to originate through an unexpected and quite disparate biosynthetic pathway. By leveraging a pyridine dearomatization/cycloaddition strategy, we developed a concise pathway to the 5,6-fused bicyclic azaindane core and, after significant experimentation, an ultimate synthesis of altemicidin itself. Tactics to productively manipulate the multiple functional groups present on this highly polar scaffold proved challenging but were eventually realized via several carefully orchestrated and chemoselective transformations-investments that paid dividends in the form of significantly shorter chemical synthesis. Surprisingly, the bond-forming logic between our presumed abiotic synthetic strategy to this alkaloid class and its subsequently identified biosynthetic pathway is eerily similar.
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Affiliation(s)
- Claire
S. Harmange Magnani
- Department
of Chemistry, University of California,
Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - José R. Hernández-Meléndez
- Department
of Chemistry, University of California,
Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Dean J. Tantillo
- Department
of Chemistry, University of California−Davis; 1 Shields Avenue, Davis, California 95616, United States
| | - Thomas J. Maimone
- Department
of Chemistry, University of California,
Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
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5
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Barra L, Awakawa T, Abe I. Noncanonical Functions of Enzyme Cofactors as Building Blocks in Natural Product Biosynthesis. JACS AU 2022; 2:1950-1963. [PMID: 36186570 PMCID: PMC9516700 DOI: 10.1021/jacsau.2c00391] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 08/05/2022] [Accepted: 08/05/2022] [Indexed: 06/16/2023]
Abstract
Enzymes involved in secondary metabolite biosynthetic pathways have typically evolutionarily diverged from their counterparts functioning in primary metabolism. They often catalyze diverse and complex chemical transformations and are thus a treasure trove for the discovery of unique enzyme-mediated chemistries. Besides major natural product classes, such as terpenoids, polyketides, and ribosomally or nonribosomally synthesized peptides, biosynthetic investigations of noncanonical natural product biosynthetic pathways often reveal functionally distinct enzyme chemistries. In this Perspective, we aim to highlight challenges and opportunities of biosynthetic investigations on noncanonical natural product pathways that utilize primary metabolites as building blocks, otherwise generally considered as enzyme cofactors. A focus is made on the discovered chemical and enzymological novelties.
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Affiliation(s)
- Lena Barra
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Department
of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Takayoshi Awakawa
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative
Research Institute of Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Ikuro Abe
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative
Research Institute of Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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6
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Cao MY, Ma BJ, Gu QX, Fu B, Lu HH. Concise Enantioselective Total Synthesis of Daphenylline Enabled by an Intramolecular Oxidative Dearomatization. J Am Chem Soc 2022; 144:5750-5755. [PMID: 35289615 DOI: 10.1021/jacs.2c01674] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Daphenylline is a structurally unique member of the triterpenoid Daphniphyllum natural alkaloids, which exhibit intriguing biological activities. Six total syntheses have been reported, five of which utilize aromatization approaches. Herein, we report a concise protecting-group-free total synthesis by means of a novel intramolecular oxidative dearomatization reaction, which concurrently generates the critical seven-membered ring and the quaternary-containing vicinal stereocenters. Other notable transformations include a tandem reductive amination/amidation double cyclization reaction, to assemble the cage-like architecture, and installation of the other two chiral stereocenters via a highly enantioselective rhodium-catalyzed challenging hydrogenation of the diene intermediate (90% e.e.) and an unprecedented remote acid-directed Mukaiyama-Michael reaction of the complex benzofused cyclohexanone (13:1 d.r.).
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Affiliation(s)
- Meng-Yue Cao
- Department of Chemistry, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.,Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Bin-Jie Ma
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Qing-Xiu Gu
- Department of Chemistry, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.,Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Bei Fu
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Hai-Hua Lu
- Department of Chemistry, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.,Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
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7
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β-NAD as a building block in natural product biosynthesis. Nature 2021; 600:754-758. [PMID: 34880494 DOI: 10.1038/s41586-021-04214-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 11/04/2021] [Indexed: 01/07/2023]
Abstract
ABSTRATCT β-Nicotinamide adenine dinucleotide (β-NAD) is a pivotal metabolite for all living organisms and functions as a diffusible electron acceptor and carrier in the catabolic arms of metabolism1,2. Furthermore, β-NAD is involved in diverse epigenetic, immunological and stress-associated processes, where it is known to be sacrificially utilized as an ADP-ribosyl donor for protein and DNA modifications, or the generation of cell-signalling molecules3,4. Here we report the function of β-NAD in secondary metabolite biosynthetic pathways, in which the nicotinamide dinucleotide framework is heavily decorated and serves as a building block for the assembly of a novel class of natural products. The gatekeeping enzyme of the discovered pathway (SbzP) catalyses a pyridoxal phosphate-dependent [3+2]-annulation reaction between β-NAD and S-adenosylmethionine, generating a 6-azatetrahydroindane scaffold. Members of this novel family of β-NAD-tailoring enzymes are widely distributed in the bacterial kingdom and are encoded in diverse biosynthetic gene clusters. The findings of this work set the stage for the discovery and exploitation of β-NAD-derived natural products.
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