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Palladium-Catalyzed Cross Coupling; Heck Coupling Reaction

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Acoplamiento cruzado alquilado regioselectivo de enlaces C-H remotos no activados

Scott M Thullen¹, Sean M Treacy¹, Tomislav Rovis¹

¹Department of Chemistry , Columbia University , New York , New York 10027 , United States.

Journal of the American Chemical Society

|September 4, 2019

Resumen

Este estudio introduce un nuevo método para la funcionalización de C ((sp3) -H, que permite el acoplamiento selectivo de enlaces C ((sp3) -H no activados con bromuros de alquilo mediante fotorreducción y catálisis de níquel.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

Los enlaces C(sp3)-H no activados son difíciles de funcionalizar debido a su baja reactividad y similitud estructural.
El desarrollo de métodos selectivos para la funcionalización de C ((sp3) -H es crucial para la síntesis de moléculas orgánicas complejas.

Objetivo del estudio:

Desarrollar un método regioselectivo para el acoplamiento de enlaces C ((sp3) -H no activados con bromuros de alquilo.
Para utilizar un sistema catalítico combinado de fotorreducción y níquel para esta transformación.

Principales métodos:

Utilizando un sistema catalítico dual que incluye catalizadores de fotorreducción y níquel.
Utilizando un grupo de dirección de amida pendiente para lograr la regioselectividad a través de la transferencia de átomo de 1,5-hidrógeno (HAT).
Interceptación del radical intermedio generado con un catalizador de níquel para la alquilación.

Principales resultados:

Se logra el acoplamiento regioselectivo de enlaces C(sp3) -C(sp3) -H no activados y bromuros de alquilo.
Se ha demostrado un buen rendimiento y una excelente selectividad en la reacción de alquilación distal.
El mecanismo 1,5-HAT dicta la selectividad posicional de la reacción.

Conclusiones:

El sistema catalítico fotoredox/níquel desarrollado proporciona una estrategia eficaz para la funcionalización regioselectiva de enlaces C ((sp3) -H no activados.
Este método ofrece una herramienta valiosa para construir enlaces C-C en síntesis orgánica compleja.
El uso de una amida pendiente para HAT es clave para lograr una alta selectividad posicional.

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