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Síntesis enantioselectiva catalítica de alfa-aminooxí y alfa-hidroxicetona mediante el uso de nitrosobenzeno

Norie Momiyama¹, Hisashi Yamamoto

¹Department of Chemistry, University of Chicago, 5735 South Ellis Avenue, Illinois 60637, USA.

Journal of the American Chemical Society

|June 6, 2003

Resumen

Un nuevo método catalítico permite reacciones altamente enantioselectivas de nitroso-aldol utilizando complejos (R) -BINAP-plata. Este enfoque sintetiza de manera eficiente las aminooxicetonas, precursores de las valiosas alfa-hidroxicetonas con alta enantiopuridad.

Área de la Ciencia:

Química orgánica es la química orgánica.
Catalización asimétrica por catálisis asimétrica.
Metodología sintética de la metodología sintética.

Sus antecedentes:

Las reacciones de nitroso-aldol son cruciales para la formación de enlaces carbono-carbono.
Lograr una alta enantioselectividad y regioselectividad (O- vs. N-alquilación) en estas reacciones sigue siendo un desafío.
El desarrollo de sistemas catalíticos para la O-alquilación enantioselectiva es de gran interés.

Objetivo del estudio:

Desarrollar una reacción catalítica de nitroso aldol altamente enantioselectiva y O-selectiva.
Explorar el uso de los complejos (R) -BINAP-plata como catalizadores para esta transformación.
Para establecer una ruta eficiente a las cetonas alfa-hidroxi enriquecidas enantioméricamente.

Principales métodos:

El estudio empleó enolados de estaño y nitrosobenzeno como sustratos.
Se investigó un sistema catalítico que utilizaba complejos (R) -BINAP-plata.
Se examinaron varias sales de plata para optimizar las condiciones de reacción, incluido el triflato de plata (AgOTf) y el perclorato de plata (AgClO4).

Principales resultados:

La reacción desarrollada logró una alta enantioselectividad, con hasta un 97% de exceso enantiomérico (ee).
Se observó una excelente regioselectividad para la O-alquilación sobre la N-alquilación (>99:1).
El producto de aminooxicetona resultante podría convertirse en alfa-hidroxicetona sin pérdida de enantiopuridad.

Conclusiones:

Se ha establecido una nueva y eficiente reacción catalítica enantioselectiva O-selectiva de nitroso aldol.
El sistema complejo (R) -BINAP-plata proporciona una poderosa herramienta para acceder a las aminooxicetonas enriquecidas enantioméricamente.
Esta metodología ofrece una valiosa estrategia sintética para la introducción catalítica enantioselectiva de oxígeno alfa a grupos carbonilo.

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