Catálisis de las dienaminas: organocatalítica asimétrica gamma-aminación de alfa, beta-aldehídos insaturados
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Søren Bertelsen1, Mauro Marigo, Sebastian Brandes
1The Danish National Research Foundation: Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
Journal of the American Chemical Society
|September 28, 2006
Resumen
Este estudio introduce un nuevo método de organocatálisis para la gamma-aminación asimétrica directa de aldehídos insaturados. Las aminas secundarias permiten esta reacción, logrando altas enantioselectividades para varios sustratos.
Área de la Ciencia:
- La organocatálisis es una catálisis orgánica.
- Síntesis asimétrica de síntesis.
- Química orgánica es la química orgánica.
Sus antecedentes:
- Los aldehídos alfa, beta insaturados suelen someterse a reacciones en la posición beta.
- La funcionalización directa en la posición gamma de estos compuestos es un desafío.
- El desarrollo de nuevos métodos catalíticos para la funcionalización selectiva es crucial en la síntesis orgánica.
Objetivo del estudio:
- Para presentar un nuevo concepto en organocatálisis: la funciónlización gamma asimétrica directa de aldehídos alfa, beta insaturados.
- Para demostrar el uso de aminas secundarias para invertir la reactividad de estos aldehídos para la gamma-aminación.
- Explorar el alcance y la enantioselectividad de esta nueva transformación.
Principales métodos:
- Utilizando las aminas secundarias como catalizadores.
- Empleando azodicarboxilatos como fuentes electrófilas de nitrógeno.
- Investigando el alcance de la reacción con varios aldehídos alfa, beta insaturados.
- Realización de estudios experimentales y cálculos de la Teoría Funcional de la Densidad (DFT).
Principales resultados:
- Exitosa gamma-aminación asimétrica directa directa de aldehídos alfa y beta insaturados.
- Se obtienen rendimientos de moderados a buenos para los productos sintetizados.
- Se observaron altas enantioselectividades, que alcanzan hasta el 93% ee.
- Mecanismo de reacción propuesto que involucra una cicloadición hetero-Diels-Alder.
Conclusiones:
- Las aminas secundarias pueden invertir efectivamente la reactividad de los aldehídos alfa, beta insaturados para la gamma-aminación directa.
- El método desarrollado proporciona acceso a compuestos de carbonilo gamma-aminados enriquecidos enantioméricamente.
- El mecanismo hetero-Diels-Alder propuesto explica los resultados estereoquímicos observados, ofreciendo nuevos conocimientos sobre las transformaciones organocatalíticas.
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