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Hidroformilación enantioselectiva por un catalizador Rh atrapado en una metallocalización supramolecular
Cristina García-Simón1, Rafael Gramage-Doria, Saeed Raoufmoghaddam
1Grup de Química Bioinorgànica i Supramolecular, Institut de Química Computacional i Catàlisi, and Departament de Química, Universitat de Girona. Campus Montilivi , Girona E17071 Catalonia, Spain.
Journal of the American Chemical Society
|January 31, 2015
Resumen
Los catalizadores quirales de rodio encapsulados en jaulas supramoleculares mejoran la hidroformilación enantioselectiva de los estirenos. Este control quiral indirecto, similar a las enzimas, aumenta la estereoselectividad para la catálisis asimétrica avanzada.
Área de la Ciencia:
- Química supramolecular de las moléculas.
- Catalización asimétrica por catálisis asimétrica.
- Química organometálica Química orgánica de los metales.
Sus antecedentes:
- Lograr una alta regioselectividad y enantioselectividad en la hidroformilación sigue siendo un desafío.
- Los catalizadores quirales a menudo requieren un control preciso de su esfera de coordinación para un rendimiento óptimo.
- La química supramolecular ofrece nuevas estrategias para el diseño y el control de catalizadores.
Objetivo del estudio:
- Desarrollar un catalizador supramolecular para la hidroformilación regio y enantioselectiva de estirenos.
- Investigar el efecto de la encapsulación del catalizador dentro de una jaula supramolecular sobre la actividad catalítica y la selectividad.
- Explorar el mecanismo de la enantioselectividad mejorada a través del control quiral indirecto.
Principales métodos:
- El autoensamblaje impulsado por la coordinación de complejos de dipalladio macrocíclicos y porfirinas de zinc tetracarboxilato para formar una jaula supramolecular no quiral.
- Encapsulación de un complejo Rh quiral dentro de la jaula autoensamblada.
- Reacciones de hidroformilación regioselectiva y enantioselectiva utilizando los catalizadores encapsulados y no encapsulados.
- Análisis espectroscópico (por ejemplo, RMN, UV-Vis) para estudiar las propiedades del catalizador y la esfera de coordinación.
Principales resultados:
- El catalizador supramolecular logró la hidroformilación regio y enantioselectiva de los estirenos.
- La encapsulación mejoró significativamente la inducción quiral en comparación con el catalizador Rh no encapsulado.
- Los datos espectroscópicos no indicaron cambios en las propiedades electrónicas o en la primera esfera de coordinación del catalizador Rh tras la encapsulación.
- La enantioselectividad mejorada se atribuyó a modificaciones en la segunda esfera de coordinación inducida por el entorno de la jaula.
Conclusiones:
- La encapsulación del catalizador dentro de las jaulas supramoleculares puede mejorar efectivamente la enantioselectividad en la catálisis asimétrica.
- El control indirecto de la quiralidad a través del espacio, imitando los mecanismos enzimáticos, es una estrategia viable para mejorar la estereoselectividad.
- Las cápsulas supramoleculares de tamaño ajustable son muy prometedoras para el desarrollo futuro de catalizadores asimétricos avanzados.
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