Catalyst-free synthesis of coumarin-, quinolone- and pyridine-annulated oxazole derivatives
An efficient approach for the synthesis of coumarin-, quinolone- and pyridine-annulated oxazole derivatives has been achieved by direct base-mediated intramolecular carbon–oxygen bond formation in a transition metal catalyst-free protocol. Intramolecular cyclization of o-bromoamides in DMSO in the p...
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Veröffentlicht in: | Tetrahedron letters 2012-03, Vol.53 (13), p.1553-1557 |
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Hauptverfasser: | , , , |
Format: | Artikel |
Sprache: | eng |
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Online-Zugang: | Volltext |
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Zusammenfassung: | An efficient approach for the synthesis of coumarin-, quinolone- and pyridine-annulated oxazole derivatives has been achieved by direct base-mediated intramolecular carbon–oxygen bond formation in a transition metal catalyst-free protocol. Intramolecular cyclization of o-bromoamides in DMSO in the presence of Cs2CO3 at 130°C affords heterocycle-annulated oxazole derivatives in high yields via a nucleophilic addition of amide to form the C–O bond. |
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ISSN: | 0040-4039 1873-3581 |
DOI: | 10.1016/j.tetlet.2012.01.015 |