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Adiciones enantioselectivas catalizadas por tiurea a los iones de oxocarbenio
Sarah E Reisman1, Abigail G Doyle, Eric N Jacobsen
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Journal of the American Chemical Society
|May 16, 2008
Resumen
Los catalizadores quirales de urea y tiurea permiten reacciones enantioselectivas de los iones de oxocarbenio. Estos catalizadores facilitan la sustitución de acetales de sililceteno por 1-cloroisocromos, con los derivados terciarios de amida bencílica mostrando los mejores resultados.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Catalización asimétrica por catálisis asimétrica.
Sus antecedentes:
- Los iones de oxocarbenio son importantes intermediarios en la síntesis orgánica.
- Desarrollar métodos enantioselectivos para sus reacciones es crucial para crear moléculas quirales.
Objetivo del estudio:
- Para reportar reacciones asimétricas y catalíticas que involucran iones de oxocarbenio.
- Investigar el uso de la urea quiral y los derivados de la tiurea como catalizadores para las transformaciones enantioselectivas.
Principales métodos:
- Utilizado sencillo, la urea quiral y los derivados de la tiurea como catalizadores.
- Investigó la reacción de sustitución de acetales de sililceteno en 1-cloroisocromos.
- Estructuras catalizadoras analizadas, particularmente aquellas con grupos terciarios de amida bencílica.
Principales resultados:
- Se ha demostrado el éxito de las reacciones de sustitución enantioselectiva catalizadas por la urea quiral y los derivados de la tiurea.
- Se identificaron catalizadores terciarios que contienen amida bencílica como los que proporcionan las enantioselectividades más altas.
- Se descubrió que las estructuras óptimas del catalizador se derivaban de derivados de 2-arilpirrolidina enriquecidos con enantio.
Conclusiones:
- La urea quiral y los derivados de la tiurea son catalizadores efectivos para la química asimétrica de iones de oxocarbenio.
- Se propone la unión de aniones por el catalizador quiral para generar el intermediario reactivo de iones de oxocarbenio.
- La síntesis enantioselectiva se puede lograr utilizando catalizadores quirales a medida derivados de las estructuras de pirrolidina.
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