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Catalizador, Z selectivo, Semi-hidrogenación de alquinas con un complejo de anilidos de zinc

Greg J Baker¹, Andrew J P White¹, Ian J Casely²

¹Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, White City, London W12 0BZ, United Kingdom.

Journal of the American Chemical Society

|March 27, 2023

Resumen

Este estudio detalla un nuevo complejo de zinc que activa el dihidrógeno (H2) para la hidrozincación de compuestos insaturados. Este descubrimiento permite la semi-hidrogenación selectiva de los alquinos, ofreciendo una nueva vía catalítica.

Área de la Ciencia:

Química organometálica
Catálisis
Química inorgánica

Sus antecedentes:

La activación del dihidrógeno (H2) es crucial para la hidrogenación catalítica.
El desarrollo de sistemas catalíticos selectivos y eficientes sigue siendo un desafío clave en la química.
Los complejos de zinc ofrecen potencial para nuevas transformaciones catalíticas.

Objetivo del estudio:

Informar sobre la activación reversible del dihidrógeno mediante el uso de un complejo de anilida de zinc molecular.
Para aclarar el mecanismo de activación de H2 y las reacciones subsiguientes de hidrozincación.
Desarrollar un sistema catalítico para la semi-hidrogenación selectiva de las alquinas.

Principales métodos:

Experimentos estequiométricos para sondear los mecanismos de reacción.
Cálculos de la Teoría Funcional de la Densidad (DFT) para conocimientos mecanicistas.
Estudios de hidrocinación con varios sustratos insaturados (alquinas, alquenos y alcadinas).

Principales resultados:

La activación de H2 ocurre a través de un estado de transición de cuatro miembros que implica la adición de enlaces Zn-N.
El complejo de hidróxido de zinc resultante efectivamente hidrozincaetas enlaces C = C (alquinas, alquenos, 1,3-butadiina).
La hidrozinación de los alquinos es estereospecífica (isómero sin) y más rápida que la de los alquenos.
Se desarrolló un sistema catalítico para la semi-hidrogenación selectiva de alquinos con altas relaciones Z:E.

Conclusiones:

El complejo de anilido de zinc facilita la activación reversible de H2 y la hidrozincación.
Este trabajo presenta el primer ejemplo de catálisis de hidrogenación selectiva utilizando complejos de zinc.
El sistema catalítico desarrollado es prometedor para las transformaciones selectivas de alquinos.

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