Synthèse d'isoxazoles substitués en α de l'oxygène et d'isoxazoles substitués en α de l'azote et de l'oxygène par des chaînes alkyle ou alcényle
| Autor: | Jean-Claude Cherton, N. Lefebvre, Marc Lanson, D. Ladjama, J-J. Basselier, Z. Vossough |
|---|---|
| Rok vydání: | 1991 |
| Předmět: | |
| Zdroj: | Canadian Journal of Chemistry. 69:625-631 |
| ISSN: | 1480-3291 0008-4042 |
| DOI: | 10.1139/v91-095 |
| Popis: | Two series of isoxazoles substituted by long alkyl or alkenyl chains in the α position with respect to the oxygen atom or in the α position with respect to the two heteroatoms have been synthesized. Starting from 3,5-dimethylisoxazole, the regioselective metalation/alkylation on the α-O methyl group was a very convenient route to a large variety of "α-O substituted isoxazoles". When applied to α-O methylated isoxazoles bearing an α-N alkenyl chain the same method provides an original unequivocal approach to 3,5-dialkenyl isoxazoles. An alternative route to these compounds, despite the formation of di-isoxazoline as by-product and an additional step corresponding to the oxidation of the intermediate isoxazoline, is the 1,3-dipolar cycloaddition, by using terminal dienes as dipolarophiles with alkenyl dipoles. Nevertheless, the cycloaddition between monoalkylated alcynes and alkylated dipoles remains the most straightforward synthesis of 3,5-dialkyl isoxazoles. Key words: isoxazoles, alkenyl side chains, metalation–alkylation, regioselectivity. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|