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Allene C ((sp²) -H Activación y alquenilación catalizada por el paladio

Benedikt S Schreib¹, Mina Son², Françoise A Aouane¹

¹ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093 Zurich, Switzerland.

Journal of the American Chemical Society

|December 16, 2021

Resumen

Este estudio introduce un nuevo método catalizado por el paladio para la alquenilización C-H de los alenos, dando como resultado penta-1,2,4-trienos. Los grupos directores de picolinamida facilitan esta reacción y se pueden eliminar fácilmente después de la síntesis.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

La activación selectiva del enlace C ((sp2) -H en los allenos es un desafío debido a su reactividad inherente.
La catálisis de metales de transición ofrece potencial para la funcionalización controlada de los allenes.

Objetivo del estudio:

Desarrollar una alquenilación C-H catalizada por el paladio de alenos electrónicamente imparciales.
Explorar el uso de grupos de dirección para la activación selectiva de C-H de los allenos.
Para sintetizar los derivados del penta-1,2,4-trieno.

Principales métodos:

Alquenilación de C-H catalizada por el paladio utilizando grupos de dirección de picolinamida.
Estudios mecanicistas que incluyen investigaciones experimentales y computacionales.
Aplicación de los N,O-acetales de picolinamida como auxiliares extraíbles

Principales resultados:

Se obtienen altos rendimientos (hasta el 94%) de productos de penta-1,2,4-trieno.
Se demostró la formación de ciclos de alenilo-pallada y un mecanismo de reacción de tipo Heck.
Utilizó con éxito picolinamida N,O-acetales para la alquenilación de derivados del alenilacarbinol.
Se ha confirmado la fácil eliminación de los grupos de dirección sin degradación del producto.

Conclusiones:

Desarrolló una eficiente alquenilación C-H catalizada por Pd de los alenos.
Se estableció una vía mecanicista que incluye la dirección de la asistencia del grupo y el acoplamiento tipo Heck.
Se han introducido picolinamidas N,O-acetales fácilmente extraíbles como auxiliares valiosos para la activación de C-H.

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