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Ligandos de Dendriphos hexacationales en la reacción de acoplamiento cruzado Suzuki-Miyaura catalizada por Pd:
Dennis J M Snelders1, Gerard van Koten, Robertus J M Klein Gebbink
1Chemical Biology and Organic Chemistry, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Journal of the American Chemical Society
|July 31, 2009
Resumen
Un nuevo sistema catalítico que utiliza ligandos de Dendriphos con paladio demuestra una alta actividad en las reacciones de acoplamiento cruzado Suzuki-Miyaura. Este sistema combina eficientemente los cloruros de arilo y los bromuros a bajas cargas de paladio, superando el rendimiento de los catalizadores tradicionales.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Síntesis orgánica La síntesis orgánica.
Sus antecedentes:
- El acoplamiento cruzado Suzuki-Miyaura es una reacción vital en la síntesis orgánica.
- El desarrollo de catalizadores de paladio altamente activos y eficientes es crucial para la química sostenible.
- Los ligandos de fosfina convencionales a menudo requieren altas cargas de paladio o condiciones adversas.
Objetivo del estudio:
- Desarrollar un sistema catalítico basado en paladio altamente activo para el acoplamiento cruzado Suzuki-Miyaura.
- Para investigar el papel de los ligandos de Dendriphos hexacationales basados en triarilfosfina en la catálisis.
- Para explorar la actividad catalítica con sustratos difíciles como cloruros de arilo y bromuros.
Principales métodos:
- Se utilizó un sistema catalítico compuesto por Pd{2) dba{3) x CHCl{3) y los ligandos de Dendriphos (1-3).
- Reacciones de acoplamiento cruzado Suzuki-Miyaura realizadas en condiciones suaves con baja carga de paladio (0,1 mol %).
- Se realizaron experimentos de control y envenenamiento para identificar las especies catalíticas activas.
Principales resultados:
- Logró una alta actividad catalítica en el acoplamiento de bromuros de arilo no activados y cloruros de arilo activados.
- Demostró una actividad significativamente mayor en comparación con los catalizadores convencionales de paladio-triarilfosfina.
- Se identificó un complejo homogéneo Pd(0)-Dendriphos como la especie activa.
- Se observó un efecto cinético dendrítico positivo para los cloruros de arilo, atribuido a la estabilización estérica por generaciones de ligandos superiores.
Conclusiones:
- Los ligandos de Dendriphos hexacationales promueven la formación de especies voluminosas, coordinadamente insaturadas Pd{0}, mejorando la actividad catalítica.
- Las cargas catiónicas y la masa estérica de los ligandos de Dendriphos son clave para su rendimiento superior.
- El sistema catalítico ofrece una ruta eficiente para el acoplamiento Suzuki-Miyaura, particularmente para los cloruros de arilo, con potencial para aplicaciones más amplias.
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