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Luo CH, Wang PL, Chang CC. Cascade Vinyl Radical Ipso-Cyclization Reactions and the Formation of α,β-Unsaturated-β-aryl-γ-lactams from N-Propargyl Benzamides. J Org Chem 2021; 86:15033-15044. [PMID: 34591475 DOI: 10.1021/acs.joc.1c01717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Various N-(2-bromo-allyl) benzamides were used as the starting materials to study vinyl radical cyclization reactions. The vinyl radicals underwent ipso-cyclization, fragmentation, and cyclization reactions to produce β-aryl-γ-lactams with the carbonyl group remaining intact. To further study this cascade radical reaction, vinyl radicals were generated by the addition of a tributyltin radical to alkyne moieties, followed by radical ipso-cyclization, fragmentation, cyclization, and β-scission reactions with the production of a series of α,β-unsaturated-β-aryl-γ-lactam derivatives. This new type of radical reaction was examined from the substituent effects on both the amino groups and the aryl groups. A bulky tert-butyl substituent on the amino group enhanced the formation of a Z-conformation of the benzamides and facilitated vinyl radical ipso-cyclization reactions. A synthetic method for preparing α,β-unsaturated-β-aryl-γ-lactams from N-propargyl benzamides was developed.
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Affiliation(s)
- Chih-Hao Luo
- Department of Chemistry, Fu Jen Catholic University, 510 Zhongzheng Road, Xinzhuang District, New Taipei City, 24205 Taiwan
| | - Pei-Ling Wang
- Department of Chemistry, Fu Jen Catholic University, 510 Zhongzheng Road, Xinzhuang District, New Taipei City, 24205 Taiwan
| | - Che-Chien Chang
- Department of Chemistry, Fu Jen Catholic University, 510 Zhongzheng Road, Xinzhuang District, New Taipei City, 24205 Taiwan
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Sun K, Lv QY, Lin YW, Yu B, He WM. Nitriles as radical acceptors in radical cascade reactions. Org Chem Front 2021. [DOI: 10.1039/d0qo01058h] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The application of the cyano group as a radical acceptor in the cascade reactions for the construction of various important heterocycles and carbocycles was summarized.
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Affiliation(s)
- Kai Sun
- Green Catalysis Center
- College of Chemistry
- Zhengzhou University
- Zhengzhou 450001
- China
| | - Qi-Yan Lv
- Green Catalysis Center
- College of Chemistry
- Zhengzhou University
- Zhengzhou 450001
- China
| | - Ying-Wu Lin
- School of Chemistry and Chemical Engineering
- University of South China
- Hengyang
- China
| | - Bing Yu
- Green Catalysis Center
- College of Chemistry
- Zhengzhou University
- Zhengzhou 450001
- China
| | - Wei-Min He
- Department of Chemistry
- Hunan University of Science and Engineering
- Yongzhou 425100
- China
- Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation
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Lynch DM, Scanlan EM. Thiyl Radicals: Versatile Reactive Intermediates for Cyclization of Unsaturated Substrates. Molecules 2020; 25:E3094. [PMID: 32646036 PMCID: PMC7412111 DOI: 10.3390/molecules25133094] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 06/30/2020] [Accepted: 07/02/2020] [Indexed: 01/11/2023] Open
Abstract
Sulfur centered radicals are widely employed in chemical synthesis, in particular for alkene and alkyne hydrothiolation towards thioether bioconjugates. The steadfast radical chain process that enables efficient hydrothiolation has been explored in the context of cascade reactions to furnish complex molecular architectures. The use of thiyl radicals offers a much cheaper and less toxic alternative to the archetypal organotin-based radical methods. This review outlines the development of thiyl radicals as reactive intermediates for initiating carbocyclization cascades. Key developments in cascade cyclization methodology are presented and applications for natural product synthesis are discussed. The review provides a chronological account of the field, beginning in the early seventies up to very recent examples; a span of almost 50 years.
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Affiliation(s)
| | - Eoin M. Scanlan
- School of Chemistry and Trinity Biomedical Sciences Institute (TBSI), Trinity College Dublin, The University of Dublin, Dublin 2, Ireland;
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Heteroatom-Centred Radicals for the Synthesis of Heterocyclic Compounds. TOPICS IN HETEROCYCLIC CHEMISTRY 2018. [DOI: 10.1007/7081_2018_19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Zhao W, Montgomery J. Functionalization of Styrenes by Copper-Catalyzed Borylation/ortho-Cyanation and Silver-Catalyzed Annulation Processes. Angew Chem Int Ed Engl 2015; 54:12683-6. [DOI: 10.1002/anie.201507303] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Indexed: 11/11/2022]
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Zhao W, Montgomery J. Functionalization of Styrenes by Copper-Catalyzed Borylation/ortho-Cyanation and Silver-Catalyzed Annulation Processes. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201507303] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Affiliation(s)
- Fabrice Dénès
- Laboratoire CEISAM UMR CNRS 6230 - UFR des Sciences et Techniques, Université de Nantes , 2 rue de la Houssinière, BP 92208 - 44322 Nantes Cedex 3, France
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Massi A, Nanni D. Thiol-yne coupling: revisiting old concepts as a breakthrough for up-to-date applications. Org Biomol Chem 2012; 10:3791-807. [PMID: 22491759 DOI: 10.1039/c2ob25217a] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Radical thiol-yne coupling (TYC) has emerged as one of the most appealing click chemistry procedures, appearing as a sound candidate for replacing/complementing other popular click reactions such as the thiol-ene coupling (TEC) and the Cu-catalysed azide-alkyne cycloaddition (CuAAC). Radical TYC is indeed a metal-free reaction suitable for biomedical applications, and its mechanistic features often make it more efficient than its TEC sister reaction and more suitable for multifaceted derivatisations in the materials chemistry and bioconjugation realms. This article reviews the fascinating results obtained in those fields in very recent years.
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Vervisch K, D'hooghe M, Törnroos KW, De Kimpe N. Radical-mediated nitrile translocation as the key step in the stereoselective transformation of 2-(4-chloro-2-cyanobutyl)aziridines to methyl cis-(1-arylmethyl-4-phenylpiperidin-2-yl)acetates. Org Biomol Chem 2012; 10:3308-14. [DOI: 10.1039/c2ob07062f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Minozzi M, Monesi A, Nanni D, Spagnolo P, Marchetti N, Massi A. An insight into the radical thiol/yne coupling: the emergence of arylalkyne-tagged sugars for the direct photoinduced glycosylation of cysteine-containing peptides. J Org Chem 2010; 76:450-9. [PMID: 21175145 DOI: 10.1021/jo101906j] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
An explorative study of the Thiol-Yne Coupling (TYC) reaction has been carried out using an aliphatic (1-octyne) and an aromatic alkyne (phenylacetylene) and two alkanethiols (methyl thioglycolate and N-acetyl-L-cysteine methyl ester). The outcomes of the TYC reactions strongly depend on the experimental conditions (e.g., temperature, solvent, and alkyne/thiol ratio), but these can be properly adjusted to achieve selective production of either mono- or bis-coupling products. With respect to 1-octyne, phenylacetylene undergoes notably easier radical hydrothiolation, further showing a notably higher aptitude for monohydrothiolation exclusive of bis-hydrothiolation. The overall findings were exploited in glycosylation of cysteine derivatives as well as of cysteine-containing peptides. A sugar featuring an arylacetylene moiety gave rise to a true click-reaction, that is, glycosylation of the tripeptide glutathione in its native form, by means of virtually equimolar amounts of reagents. This reaction was successfully applied, under physiological conditions, to a cysteine-containing nonapeptide with marked advantages over the analogous Thiol-Ene Coupling (TEC) derivatization. A TYC/TEC sequence affording bis-armed cysteine derivatives through dual functionalization of an alkynyl sugar was additionally devised.
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Affiliation(s)
- Matteo Minozzi
- Dipartimento di Chimica Organica A. Mangini, Università di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy
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Sato A, Yorimitsu H, Oshima K. Radical Additions of Arenethiols to Ynamides for the Selective Synthesis of N-[(Z)-2-(Arylsulfanyl)-1-alkenyl]amides. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.03.570] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Taniguchi T, Fujii T, Idota A, Ishibashi H. Reductive Addition of the Benzenethiyl Radical to Alkynes by Amine-Mediated Single Electron Transfer Reaction to Diphenyl Disulfide. Org Lett 2009; 11:3298-301. [DOI: 10.1021/ol901084k] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tsuyoshi Taniguchi
- School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Tatsuya Fujii
- School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Atsushi Idota
- School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Hiroyuki Ishibashi
- School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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Montevecchi PC, Navacchia ML. THIOL MEDIATED 5-(π-ENDO)ORTHO VINYL RADICAL CYCLIZATIONS. PHOSPHORUS SULFUR 2006. [DOI: 10.1080/10426500008076542] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Pier Carlo Montevecchi
- a Dipartimento di Chimica Organica “A. Mangini” , Università di Bologna , Hale Risorgimento 4, I-40136, Bologna, Italy
| | - Maria Luisa Navacchia
- a Dipartimento di Chimica Organica “A. Mangini” , Università di Bologna , Hale Risorgimento 4, I-40136, Bologna, Italy
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Bowman WR, Cloonan MO, Fletcher AJ, Stein T. Synthesis of heteroarenes using cascade radical cyclisation via iminyl radicals. Org Biomol Chem 2005; 3:1460-7. [PMID: 15827642 DOI: 10.1039/b501509j] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cascade radical cyclisation involving homolytic aromatic substitution has been used to synthesise new tetracycles. Treatment of vinyl iodide radical precursors with Me(3)Sn. radicals (from hexamethylditin) yielded intermediate vinyl radicals which undergo 5-exo cyclisation onto suitably placed nitrile groups to yield intermediate iminyl radicals. The iminyl radicals undergo aromatic homolytic substitution via 6-endo cyclisation (or 5-exo cyclisation followed by neophyl rearrangement) with loss of hydrogen (H.) in a H-abstraction step. We propose that this abstraction was facilitated by tert-butoxyl (t-BuO.) radicals from di-tert-butyl peroxide or methyl radicals, generated from breakdown of trimethylstannyl radicals (Me(3)Sn.). The biologically active alkaloids mappicine and luotonin A were synthesised using the new methodology. A novel radical conversion of nitriles to primary amides is proposed.
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Affiliation(s)
- W Russell Bowman
- Department of Chemistry, Loughborough University, Leicestershire, UK.
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Tada M, Hanaoka Y. The reaction of triphenylstannylcobaloxime with enynes under photochemical and thermal conditions. J Organomet Chem 2000. [DOI: 10.1016/s0022-328x(00)00550-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Radical addition to isonitriles: a route to polyfunctionalized alkenes through a novel three-component radical cascade reaction. J Org Chem 2000; 65:2763-72. [PMID: 10808453 DOI: 10.1021/jo991871y] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction of aromatic disulfides, alkynes, and isonitriles under photolytic conditions affords polyfunctionalized alkenes--beta-arylthio-substituted acrylamides or acrylonitriles--in fair yields through a novel three-component radical cascade reaction. The procedure entails addition of a sulfanyl radical to the alkyne followed by attack of the resulting vinyl radical to the isonitrile. A fast reaction, e.g., scavenging by a nitro derivative or beta-fragmentation, is necessary in order to trap the final imidoyl radical, since addition of vinyl radicals to isonitriles seems to be a reversible process. The stereochemistry of the reaction is discussed, particularly with respect to the stereochemical outcome of related hydrogen abstraction reactions by the same vinyl radicals. The lower or even inverted preference for either geometrical isomer observed in our cases with respect to that encountered in hydrogen abstraction reactions is explained in terms of transition-state interactions and/or isomerization of the final imidoyl radical. The latter possibility is supported by semiempirical calculations, which show that the spin distribution in the imidoyl radical can allow rotation of the adjacent carbon-carbon double bond prior to beta-fragmentation.
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Melandri D, Montevecchi PC, Navacchia ML. Thiol radical addition to alkynes. Sulfanyl radical addition and hydrogen atom abstraction relative reaction rates. Tetrahedron 1999. [DOI: 10.1016/s0040-4020(99)00699-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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