Synthesis of 4-(thien-2-yl)-substituted coumarins through Lewis acid catalyzed Michael addition of thiophenes to 3-benzoylcoumarins followed by oxidation |
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| Authors: | Roman A. Irgashev Arseny A. KarmatskyGennady L. Rusinov Valery N. Charushin |
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| Affiliation: | I. Postovsky Institute of Organic Synthesis, Ural Division, Russian Academy of Sciences, S. Kovalevskoy Str., 22, Ekaterinburg 620041, Russia; Ural Federal University named after the First President of Russia B.N. Yeltsin, Mira St. 19, Ekaterinburg 620002, Russia |
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| Abstract: | 3-Benzoyl-4-(thien-2-yl)coumarins have been obtained in good yields according to the SNH addition–oxidation protocol, involving the diastereoselective addition of thiophenes at C-4 of 3-benzoylcoumarins under BBr3 catalysis, followed by oxidation of the intermediate 3,4-trans-3-benzoyl-4-(thien-2-yl)-3,4-dihydrocoumarins with DDQ. This two-step procedure can be regarded as nucleophilic substitution of hydrogen (SNH) on the heterocyclic ring of coumarins. |
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| Keywords: | Thiophenes 3-Benzoylcoumarins Lewis acid Nucleophilic aromatic substitution of hydrogen Metal-free cross-coupling reactions Direct heteroarylation |
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