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Hidrogenación asimétrica catalítica de los N-Boc-imidazoles y los oxazoles
Ryoichi Kuwano1, Nao Kameyama, Ryuhei Ikeda
1Department of Chemistry, Graduate School of Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan. rkuwano@chem.kyushu-univ.jp
Journal of the American Chemical Society
|April 29, 2011
Resumen
Los investigadores lograron una hidrogenación altamente enantioselectiva de los imidazoles y oxazoles sustituidos en imidazolinas y oxazolinas quirales utilizando un nuevo catalizador de rutenio. Este avance permite la reducción asimétrica catalítica de anillos aromáticos heterocíclicos de cinco miembros.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Catalización asimétrica por catálisis asimétrica.
- Química Heterocíclica La Química Heterocíclica es una de las más conocidas.
Sus antecedentes:
- Los compuestos heterocíclicos quirales son bloques de construcción cruciales en los productos farmacéuticos y la ciencia de los materiales.
- Los métodos catalíticos eficientes para sintetizar las imidazolinas y oxazolinas enantioméricamente puras son muy buscados.
- Los métodos anteriores para reducir los heterociclos aromáticos de cinco miembros a menudo carecen de estereoselectividad o requieren condiciones duras.
Objetivo del estudio:
- Desarrollar un nuevo sistema catalítico para la hidrogenación asimétrica de imidazoles y oxazoles sustituidos.
- Para lograr una alta enantioselectividad en la reducción de anillos aromáticos de cinco miembros que contienen heteroátomos de nitrógeno y oxígeno.
- Establecer un nuevo método para sintetizar las imidazolinas y oxazolinas quirales.
Principales métodos:
- Hidrogenación de los imidazoles y oxazoles sustituidos utilizando un catalizador quiral de rutenio.
- El catalizador fue generado in situ a partir de Ru (η3) -metalilo (ε2) (cod) y un ligando quiral transcelatorio de la bisfosfina, PhTRAP.
- Análisis del exceso enantiomérico (ee) utilizando cromatografía quiral.
Principales resultados:
- Hidrogenación exitosa de los imidazoles y los oxazoles a sus correspondientes imidazolinas y oxazolinas quirales.
- Se logra hasta un 99% de exceso enantiomérico (ee) en los productos.
- Demostró la primera reducción asimétrica catalítica exitosa de anillos aromáticos de 5 miembros con múltiples heteroátomos.
Conclusiones:
- El sistema catalítico de rutenio-PhTRAP desarrollado proporciona una ruta altamente efectiva para la hidrogenación asimétrica.
- Este método ofrece un avance significativo en la síntesis de las imidazolinas y oxazolinas quirales enriquecidas enantioméricamente.
- Representa un avance en la reducción asimétrica catalítica de sustratos aromáticos heterocíclicos difíciles.
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