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Requisitos estructurales para la transferencia del catalizador de paladio en un enlace doble carbono-carbono
Masataka Nojima1, Yoshihiro Ohta1, Tsutomu Yokozawa1
1Department of Material and Life Chemistry, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan.
Journal of the American Chemical Society
|April 23, 2015
Resumen
Este estudio revela que los orto-sustitutos en el stilbeno
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis de la catálisis.
- Química organometálica Química orgánica de los metales.
Sus antecedentes:
- Las reacciones de acoplamiento cruzado catalizadas por el paladio son vitales en la síntesis orgánica.
- Comprender los mecanismos de transferencia de catalizadores es crucial para la optimización de la reacción.
- La transferencia de catalizador intramolecular versus intermolecular impacta en la eficiencia y la selectividad de la reacción.
Objetivo del estudio:
- Investigar el mecanismo de la transferencia del catalizador intramolecular de tris (ter-butilo) fosfina paladio (t) (Bu3PPd) en los enlaces dobles carbono-carbono (CC).
- Determinar el papel de los sustituyentes del stilbeno en el control de la transferencia del catalizador durante el acoplamiento Suzuki-Miyaura.
- Para dilucidar los factores que impiden la transferencia de catalizadores intermoleculares.
Principales métodos:
- Utilizó las reacciones de acoplamiento Suzuki-Miyaura con dibromostilbenos y ácidos/ésteres borónicos de arilo.
- Empleó varios aditivos que contienen CC como modelos para estudiar la transferencia de catalizadores.
- Se analizó la influencia de los orto-sustitutos en los enlaces CC del stilbeno.
Principales resultados:
- Se descubrió que los grupos de orto-sustitutos en los enlaces CC del stilbeno son críticos para la transferencia selectiva de catalizadores intramoleculares.
- Se demostró que estos sustituyentes suprimen la formación de complejos bimoleculares CC-Pd-CC.
- Se ha demostrado que la supresión de la formación de complejos bimoleculares impide la transferencia intermolecular de (t) Bu3PPd(0).
Conclusiones:
- La orto-sustitución en los stilbenes dirige la transferencia intramolecular del catalizador de paladio.
- El obstáculo estérico de los orto-sustitutos es clave para prevenir la transferencia de catalizadores intermoleculares.
- Este hallazgo ofrece una estrategia para controlar el comportamiento del catalizador en reacciones de acoplamiento cruzado.
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