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Aceleración inducida estéricamente de la activación del haluro de arilo por Pd(0): una alternativa radical a la

Daniel Hupperich¹, Jaime Ponce-de-León¹, Ignacio Funes-Ardoiz¹

¹Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

Journal of the American Chemical Society

|May 29, 2025

Resumen

El obstáculo estérico acelera las reacciones de acoplamiento cruzado catalizadas por el paladio. Este estudio revela un mecanismo de abstracción de halógenos de 1 electrón en entornos estéricamente exigentes, desafiando las suposiciones anteriores de 2 electrones.

Área de la Ciencia:

Química organometálica
Catálisis
Síntesis orgánica

Sus antecedentes:

El acoplamiento cruzado catalizado por paladio es crucial en la síntesis orgánica.
El paso inicial es típicamente una adición oxidativa de 2 electrones de haluro de arilo a Pd(0).
Esto forma un complejo Pd (II), un mecanismo ampliamente aceptado.

Objetivo del estudio:

Investigar el mecanismo del acoplamiento cruzado catalizado por Pd(0) con sustratos estéricamente obstaculizados.
Para desafiar el modelo convencional de transferencia de 2 electrones bajo tensión estérica.

Principales métodos:

Se utilizan bromuros de arilo estériles y catalizadores voluminosos Pd (0).
Reacciones realizadas a temperatura ambiente en una escala de gramos.
Se llevaron a cabo estudios mecanicistas para aclarar el proceso de transferencia de electrones.

Principales resultados:

Se ha observado una aceleración de la activación del haluro de arilo con un aumento de la impedancia estérica.
Se logró la conversión completa de un bromuro de arilo sustituido por di-tert-butilo en 1 minuto.
Los datos mecánicos indicaron una vía de abstracción de halógenos de 1 electrón.

Conclusiones:

La adición oxidativa convencional de 2 electrones no es el único mecanismo para el acoplamiento cruzado catalizado por Pd (0).
Un mecanismo de abstracción de halógenos de 1 electrón es operativo en entornos estéricamente congestionados.
Este hallazgo ofrece nuevas ideas sobre el diseño del catalizador y la optimización de la reacción.

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