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Reacción asimétrica de Aza-Henry bajo catálisis de transferencia de fase: un estudio experimental y teórico
Enrique Gomez-Bengoa1, Anthony Linden, Rosa López
1Departamento de Química Orgánica I, Facultad de Química, Universidad del País Vasco, Apdo. 1072, San Sebastián, 20080, Spain.
Journal of the American Chemical Society
|May 31, 2008
Resumen
Este estudio introduce una reacción aza-Henry catalítica asimétrica eficiente utilizando condiciones de transferencia de fase. El nuevo método permite la síntesis directa de valiosas aminas y ésteres quirales a partir de materiales de partida fácilmente disponibles.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Catalización asimétrica por catálisis asimétrica.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- La reacción aza-Henry es una transformación crucial para la síntesis de las beta-nitroaminas.
- El desarrollo de versiones asimétricas catalíticas es esencial para acceder a productos enriquecidos enantioméricamente.
- La catálisis de transferencia de fase ofrece ventajas en términos de condiciones de reacción y accesibilidad del catalizador.
Objetivo del estudio:
- Desarrollar una eficiente reacción catalítica asimétrica aza-Henry bajo condiciones de transferencia de fase.
- Demostrar la amplia aplicabilidad del método para sintetizar aminas y ésteres quirales.
- Para dilucidar las interacciones clave que rigen la enantioselectividad observada.
Principales métodos:
- Utilizando catalizadores de amonio derivados de cinchona con base CsOH x H2O en el tolueno.
- Reaccionan los nitroalcanos con las sulfonas alfa-amido derivadas tanto de las azometinas no enolizables como de las enolizables.
- Empleando condiciones de transferencia de fase para facilitar la reacción entre fases inmiscibles.
Principales resultados:
- Se lograron reacciones aza-Henry asimétricas catalíticas eficientes con alta enantioselectividad.
- Demostró la validez del método para varios nitroalcanos y azometinas, produciendo beta-nitroaminas.
- Proporcionó una síntesis asimétrica directa de 1,2-diaminas y gamma-amino alfa, ésteres beta-insaturados.
- Identificó un estado de transición preferido que involucra un patrón inusual de enlaces de hidrógeno.
Conclusiones:
- La reacción aza-Henry catalizada por transferencia de fase presentada es un método versátil y eficiente para la síntesis asimétrica.
- La metodología proporciona acceso directo a valiosos bloques de construcción quirales, incluidas las diaminas y los ésteres insaturados.
- El estudio ofrece información sobre el mecanismo de reacción y el control estereoquímico, allanando el camino para un mayor desarrollo de catalizadores.
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