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Inserción migratoria intermolecular de olefinas no activadas en enlaces de nitrógeno y paladio. Efectos estéricos y

Patrick S Hanley¹, John F Hartwig

¹Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States.

Journal of the American Chemical Society

|August 6, 2011

Resumen

Este estudio revela cómo las propiedades de los ligandos influyen en la inserción de alquenos catalizados por el paladio en enlaces de nitrógeno y paladio. Los factores estéricos y electrónicos de los ligandos y alquenos controlan las tasas de reacción y la formación de productos, ofreciendo información sobre los mecanismos catalíticos.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
La catálisis de la catálisis.
Síntesis orgánica La síntesis orgánica.

Sus antecedentes:

Los complejos palladio-amido son intermediarios clave en los ciclos catalíticos.
Comprender la inserción migratoria es crucial para el diseño de catalizadores eficientes.
La influencia de los ligandos auxiliares en la reactividad es compleja y requiere un estudio detallado.

Objetivo del estudio:

Investigar el impacto de las propiedades estéricas y electrónicas de los ligandos auxiliares y sustratos de alquenos en la tasa de inserción migratoria.
Para sintetizar y caracterizar nuevos complejos de amido de paladio con entornos de ligando a medida.
Para dilucidar la interacción entre la unión de alquenos y la cinética de inserción migratoria.

Principales métodos:

Síntesis de complejos de amido de paladio ligado con benzilfosfina y ciclometalado.
Observación espectroscópica de los intermediarios olefin-amido.
Estudios cinéticos de la inserción migratoria y la eliminación del beta-hidruro.
Evaluación de los efectos estéricos y electrónicos sobre las velocidades de reacción y las afinidades de unión.

Principales resultados:

El bulto estérico del ligando influye tanto en la afinidad de unión al alqueno como en las tasas de inserción migratoria.
Los ligandos auxiliares pobres en electrones aceleran la inserción migratoria.
Los vinilarenos pobres en electrones reaccionan más rápido en el paso de inserción, a pesar de los complejos menos estables.
La interacción de las energías de unión e inserción dicta la reactividad general.

Conclusiones:

Tanto las propiedades estéricas como las electrónicas de los ligandos auxiliares modulan significativamente la inserción migratoria de alquenos no activados en enlaces de nitrógeno y paladio.
Las tendencias observadas proporcionan una comprensión mecanicista de las reacciones de aminación catalizadas por paladio.
Este trabajo ofrece información valiosa para el diseño racional de catalizadores de paladio para la síntesis orgánica.

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