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Semihidrogenación alquina con un catalizador no clásico bien definido: un giro H2 en la isomerización y la

Kenan Tokmic¹, Alison R Fout¹

¹School of Chemical Sciences, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States.

Journal of the American Chemical Society

|October 7, 2016

Resumen

Este estudio introduce un catalizador de cobalto para la semihidrogenación de las alquinas internas a las transalquinas. Los estudios mecanicistas revelan una cis-hidrogenación inicial seguida de una isomerización catalizada por cobalto a E-alquenos.

Área de la Ciencia:

Química organometálica
Catálisis
Síntesis orgánica

Sus antecedentes:

Los complejos de cobalto se exploran cada vez más como catalizadores en las transformaciones orgánicas.
La semihidrogenación selectiva de los alquinos sigue siendo un desafío en la química sintética.

Objetivo del estudio:

Desarrollar un catalizador basado en cobalto para la semihidrogenación de alquinas internas.
Investigar el mecanismo de la semihidrogenación alquina catalizada por cobalto.

Principales métodos:

Se utilizó un precatalizador Co (I) -N2 para la semihidrogenación de alquinos.
Se emplean condiciones de temperatura y presión variables.
Se llevaron a cabo estudios mecanicistas utilizando espectroscopia de RMN de transferencia por polarización inducida por 1H, 2H y para-hidrógeno (PHIP).

Principales resultados:

Se ha logrado la semihidrogenación de una amplia gama de alquinas internas en alquenos.
Se ha observado la formación de productos transalquenicos con buen rendimiento y selectividad E/Z.
Los estudios de RMN indicaron una cis-hidrogenación inicial seguida de una isomerización de alqueno co-mediada.

Conclusiones:

El catalizador de cobalto desarrollado permite una semihidrogenación eficiente y selectiva de los alquinos internos.
La reacción procede a través de una única vía de cis-hidrogenación seguida de isomerización.
Este trabajo amplía la utilidad de la catálisis del cobalto en la síntesis orgánica.

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