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Efimov IV, Shafikov MZ, Beliaev NA, Volkova NN, Beryozkina TV, Dehaen W, Fan Z, Grishko VV, Lubec G, Slepukhin PA, Bakulev VA. Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides. Beilstein J Org Chem 2016; 12:2390-2401. [PMID: 28144307 PMCID: PMC5238569 DOI: 10.3762/bjoc.12.233] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 10/24/2016] [Indexed: 11/23/2022] Open
Abstract
Reactions of β-azolyl enamines and nitrile oxides were studied by both experimental and theoretical methods. (E)-β-(4-Nitroimidazol-5-yl), (5-nitroimidazol-4-yl) and isoxazol-5-yl enamines smoothly react regioselectively at room temperature in dioxane solution with aryl, pyridyl, and cyclohexylhydroxamoyl chlorides without a catalyst or a base to form 4-azolylisoxazoles as the only products in good yields. The intermediate 4,5-dihydroisoxazolines were isolated as trans isomers during the reaction of (E)-β-imidazol-4-yl enamines with aryl and cyclohexylhydroxamoyl chlorides. Stepwise and concerted pathways for the reaction of β-azolyl enamines with hydroxamoyl chlorides were considered and studied at the B3LYP/Def2-TZVP level of theory combined with D3BJ dispersion correction. The reactions of benzonitrile oxide with both E- and Z-imidazolyl enamines have been shown to proceed stereoselectively to form trans- and cis-isoxazolines, respectively. The preference of E-isomers over Z-isomers, driven by the higher stability of the former, apparently controls the stereoselectivity of the investigated cycloaddition reaction with benzonitrilе oxide. Based on the reactivity of azolyl enamines towards hydroxamoyl chlorides, a novel, effective catalyst-free method was elaborated to prepare 4-azolyl-5-substituted isoxazoles that are otherwise difficult to obtain.
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Affiliation(s)
- Ilya V Efimov
- TOS Department, Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira str., 620002 Yekaterinburg, Russia
| | - Marsel Z Shafikov
- TOS Department, Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira str., 620002 Yekaterinburg, Russia
- Chemistry Department, University of York, Heslington, York, YO10 5DD, UK
| | - Nikolai A Beliaev
- TOS Department, Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira str., 620002 Yekaterinburg, Russia
| | - Natalia N Volkova
- TOS Department, Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira str., 620002 Yekaterinburg, Russia
| | - Tetyana V Beryozkina
- TOS Department, Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira str., 620002 Yekaterinburg, Russia
| | - Wim Dehaen
- Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | - Zhijin Fan
- State Key Laboratory of Elemento-Organic Chemistry Nankai University, Collaborative Innovation Center of Chemical Science and Engineering 300071 Tianjin, China
| | - Viktoria V Grishko
- Laboratory of Biologically Active Compounds, Institute of Technical Chemistry Ural Branch of Russian Academy of Sciences, 3 Academician Korolev str., Perm, Russia
| | - Gert Lubec
- Medical University of Vienna, Department of Pediatrics, 14 Lazarettgasse, 1090 Vienna, Austria
| | - Pavel A Slepukhin
- TOS Department, Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira str., 620002 Yekaterinburg, Russia
- I. Ya. Postovsky Institute of Organic Synthesis, Ural Branch of Russian Academy of Sciences, 20 S. Kovalevskaya str., 620990 Yekaterinburg, Russia
| | - Vasiliy A Bakulev
- TOS Department, Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira str., 620002 Yekaterinburg, Russia
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Synthetic Advances in the Indane Natural Product Scaffolds as Drug Candidates. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/b978-0-444-63932-5.00008-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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