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Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions
Published on: March 20, 2014
Estudios sobre la reacción de Heck con fosfatos alquenilo: ¿se puede controlar la migración del 1,2? Alcance y
Jean-Philippe Ebran1, Anders L Hansen, Thomas M Gøgsig
1The Center for Insoluble Protein Structures inSPIN, Department of Chemistry, the Interdisciplinary Nanoscience Center, University of Aarhus, Langelandsgade 140, 8000 Aarhus, Denmark.
Journal of the American Chemical Society
|May 4, 2007
Resumen
Este estudio introduce un nuevo sistema de catalizador para las reacciones de acoplamiento de Heck, lo que permite la síntesis de productos de dieno a partir de fosfatos de vinilo simples y alquenos. El ligando de Buchwald dialkylbiarylphosphine, X-Phos, promueve efectivamente la sustitución vinílica mientras suprime la migración intermedia no deseada.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis de la catálisis.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- La reacción de acoplamiento de Heck es una herramienta poderosa para la formación de enlaces carbono-carbono.
- Desarrollar sistemas catalíticos eficientes para acoplar sustratos no activados sigue siendo un desafío.
- El control de la regioselectividad y la prevención de reacciones secundarias como la 1,2-migración son cruciales para la utilidad sintética.
Objetivo del estudio:
- Desarrollar un nuevo sistema de catalizador para el acoplamiento Heck de fosfatos de vinilo no activados con alquenos con déficit de electrones.
- Para explorar el uso de las dialkylbiarylphosphines de Buchwald (por ejemplo, X-Phos) como ligandos en esta transformación.
- Para investigar y controlar la migración 1,2-de los intermediarios de alquenil paladio.
Principales métodos:
- Utilizó cloruro de paladio (II) complejado con ciclooctadieno (PdCl2 (COD)) y dialquilbiarilfosfinas (X-Phos) de Buchwald como el sistema catalizador.
- Empleado cloruro de litio como aditivo para promover la sustitución vinílica.
- Investigó la influencia del sustituto C1 en el sustrato de fosfato de vinilo para controlar la isomerización y la migración.
- Realizó experimentos de competencia con haluros de arilo para evaluar la selectividad del catalizador.
Principales resultados:
- El ligando X-Phos promovió efectivamente el acoplamiento Heck de varios fosfatos alquenil con alquenos con déficit de electrones.
- La adición de cloruro de litio suprimió la 1,2-migración del intermediario alquenil paladio (II).
- La extensión de la migración de 1,2 fue dependiente del sustituto C1, con carbono cuaternario C1-alquilo dando resultados óptimos.
- El acoplamiento selectivo de Heck con haluros de arilo sobre fosfatos de vinilo se logró mediante una cuidadosa selección de ligandos (X-Phos vs. P(t-Bu) 3).
Conclusiones:
- Se ha desarrollado un nuevo y eficiente sistema catalítico para el acoplamiento Heck de fosfatos de vinilo no activados.
- La elección del ligando de la fosfina (X-Phos o P(t-Bu) 3 permite una síntesis preferencial de productos Heck migrados o no migrados.
- El sistema catalizador demuestra selectividad para el acoplamiento del haluro de arilo sobre la activación del enlace C-O del fosfato de vinilo.
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