Synthesis of 2-Phenyl-4,5-Substituted Oxazoles by Copper-Catalyzed Intramolecular Cyclization of Functionalized Enamides
In: Journal of organic chemistry, Jg. 77 (2012), Heft 23, S. 10752-10763
academicJournal
- print, 35 ref
Zugriff:
An efficient two-step synthesis of 2-phenyl-4,5-substituted oxazoles involving intramolecular copper-catalyzed cyclization of highly functionalized novel β-(methylthio)enamides as the key step has been reported. These enamides are obtained by nucleophilic ring-opening of newly synthesized 4-[(methylthio)hetero(aryl)methylene]-2-phenyl-5-oxazolone precursors by alkoxides, amines, amino acid esters and aryl/alkyl Grignard reagents, thus leading to the introduction of an ester, N-substituted carboxamide or acyl functionalities at 4-position of the product oxazoles. Synthesis of two naturally occurring 2,5-diaryloxazoles, i.e., texamine and uguenenazole, via two-step hydrolysis―decarboxylation of the corresponding 2,5-diaryloxazole-4-carboxylates has also been described. Similarly, three of the serine-derived oxazole-4-carboxamides were elaborated to novel trisubstituted 4,2'-bisoxazoles through DAST/DBU-mediated cyclodehydration―dehydrohalogenation sequence. The present protocol is complementary and an improvement to our previously reported silver carbonate-induced cyclization of β-bis(methylthio)enamides to 2-phenyl-5-(methylthio)-4-substituted oxazoles.
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Synthesis of 2-Phenyl-4,5-Substituted Oxazoles by Copper-Catalyzed Intramolecular Cyclization of Functionalized Enamides
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Autor/in / Beteiligte Person: | VIJAY KUMAR, S ; SARAIAH, B ; MSRA, N. C ; ILA, H |
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Zeitschrift: | Journal of organic chemistry, Jg. 77 (2012), Heft 23, S. 10752-10763 |
Veröffentlichung: | Washington, DC: American Chemical Society, 2012 |
Medientyp: | academicJournal |
Umfang: | print, 35 ref |
ISSN: | 0022-3263 (print) |
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