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Acoplamiento Suzuki-Miyaura catalizado con paladio de ésteres de arilo

Taoufik Ben Halima¹, Wanying Zhang¹, Imane Yalaoui¹

¹Centre for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa , 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.

Journal of the American Chemical Society

|December 22, 2016

Resumen

Este estudio introduce un nuevo método de acoplamiento Suzuki-Miyaura utilizando catalizadores de paladio basados en carbenos N-heterocíclicos (NHC). Este enfoque permite el uso de ésteres de arilo como electrófilos, produciendo productos cetónicos valiosos.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

El acoplamiento Suzuki-Miyaura es una reacción de piedra angular para la formación de enlaces carbono-carbono, generalmente empleando haluros de arilo o pseudohaluros.
La expansión del alcance de esta reacción a electrófilos menos reactivos sigue siendo un desafío significativo en la química sintética.
Los métodos tradicionales que utilizan ésteres similares a menudo conducen a productos biarílicos a través de la catálisis del níquel, lo que pone de relieve la necesidad de sistemas catalíticos alternativos.

Objetivo del estudio:

Desarrollar un nuevo sistema catalítico para el acoplamiento Suzuki-Miyaura utilizando ésteres de arilo como electrófilos.
Para permitir la síntesis de productos que contienen cetonas a partir de ésteres de arilo fácilmente disponibles.
Investigar las diferencias mecánicas entre la catálisis del paladio y el níquel en las reacciones de acoplamiento de ésteres.

Principales métodos:

Desarrollo de un catalizador de paladio basado en carbenos heterocíclicos (NHC).
Aplicación del catalizador en las reacciones de acoplamiento Suzuki-Miyaura con ésteres de arilo como electrófilos.
Cálculos de la Teoría Funcional de Densidad (DFT) para aclarar los mecanismos de reacción y el comportamiento del catalizador.
Análisis comparativo de la reactividad del éster frente a otros socios de acoplamiento acilativos.

Principales resultados:

Demostración exitosa del acoplamiento Suzuki-Miyaura utilizando el enlace C ((acil) -O de ésteres de arilo como el sitio electrófilo.
Síntesis de varios productos que contienen cetonas, mostrando la utilidad del método desarrollado.
Identificación de las divergencias mecánicas de las reacciones catalizadas por níquel, atribuidas al sistema catalizador NHC-Pd.
Los cálculos de DFT proporcionaron información sobre las razones subyacentes de la quimioselectividad y la reactividad observadas.

Conclusiones:

Un catalizador de paladio basado en NHC promueve efectivamente el acoplamiento de Suzuki-Miyaura con ésteres de arilo, proporcionando una nueva ruta a las cetonas.
Esta metodología amplía el alcance del acoplamiento Suzuki-Miyaura a los electrofilos anteriormente infrautilizados.
El estudio destaca la importancia del diseño del catalizador para lograr patrones de reactividad y resultados de producto distintos.

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