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Utilidad del efecto ligando en la catálisis del oro homogéneo: posibilitando la ciclización activada por enlaces π
Dong Ding, Tao Mou, Minghao Feng
1Shanghai Key Laboratory of Green Chemistry and Chemical Process, School of Chemistry and Molecular Engineering, East China Normal University , 3663 North Zhongshan Road, Shanghai, 200062, P. R. China.
Journal of the American Chemical Society
|April 9, 2016
Resumen
Este estudio demuestra un control preciso sobre la catálisis del oro para la hidroarilación de alquinos. El diseño de los ligandos dicta la regioselectividad, lo que permite la orto- o paraciclización selectiva para la síntesis de moléculas complejas.
Área de la Ciencia:
- Química orgánica
- Catálisis
- Catálisis homogénea
Sus antecedentes:
- Las propiedades de los ligandos influyen significativamente en los resultados de la catálisis homogénea.
- El control de la regioselectividad en la hidroarilación intramolecular de las alquinas sigue siendo un desafío.
Objetivo del estudio:
- Lograr la hidroariación intramolecular regiodivergente de los alquinos mediante la utilización integral de las propiedades electrónicas y estéricas de los ligandos.
- Desarrollar nuevos catalizadores para reacciones de ciclización selectiva.
Principales métodos:
- Se utilizan catalizadores catiónicos Au (I) con ligandos de fosfito y fosfina adaptados.
- Se empleó un ligando de fosfito flexible con deficiencia de electrones para la ortociclización.
- Se empleó un ligando rígido de fosfina rico en electrones para la paraciclización.
- Investigó un proceso catalítico de relé de oro y plata para sintetizar estructuras complejas.
Principales resultados:
- Se logra la ciclización de la orto-posición estéricamente obstaculizada utilizando un centro catiónico Au ((I) de tres coordenadas con un ligando fosfito y un grupo directivo de metoxilo amida.
- Se obtiene exclusivamente por ciclización de paraposiciones con un catalizador rígido basado en un ligando de fosfina abundante en electrones Au (I).
- Tetrahidropiroloquinolinonas sintetizadas con estructuras tricíclicas congestionadas mediante un proceso catalítico de relevo de Au/Ag.
Conclusiones:
- Se ha demostrado la capacidad de controlar la regioselectividad en la hidroarilación de alquinos a través del diseño estratégico del ligando en la catálisis del oro homogéneo.
- Estableció un sistema catalítico versátil para acceder a diversos productos de ciclización.
- Destacó el efecto sinérgico de los catalizadores de oro y plata en la construcción de arquitecturas moleculares complejas.
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