Studies on the Enantioselective Synthesis of E-Ethylidene-bearing Spiro[indolizidine-1,3′-oxindole] Alkaloids
A synthetic route for the enantioselective construction of the tetracyclic spiro[indolizidine-1,3′-oxindole] framework present in a large number of oxindole alkaloids, with a <i>cis</i> H-3/H-15 stereochemistry, a functionalized two-carbon substituent at C-15, and an <i>E</i>...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/227909 |
| Acceso en línea: | http://hdl.handle.net/10261/227909 |
| Access Level: | acceso abierto |
| Palabra clave: | Oxindoles Alkaloids Spiro compounds Ethylidene |
| Sumario: | A synthetic route for the enantioselective construction of the tetracyclic spiro[indolizidine-1,3′-oxindole] framework present in a large number of oxindole alkaloids, with a <i>cis</i> H-3/H-15 stereochemistry, a functionalized two-carbon substituent at C-15, and an <i>E</i>-ethylidene substituent at C-20, is reported. The key steps of the synthesis are the generation of the tetracyclic spirooxindole ring system by stereoselective spirocyclization from a tryptophanol-derived oxazolopiperidone lactam, the removal of the hydroxymethyl group, and the stereoselective introduction of the <i>E</i>-ethylidene substituent by acetylation at the α-position of the lactam carbonyl, followed by hydride reduction and elimination. Following this route, the 21-oxo derivative of the enantiomer of the alkaloid 7(<i>S</i>)-geissoschizol oxindole has been prepared. |
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