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Un método suave y catalizado por el paladio para la deshidrohalogenación de bromuros de alquilo: estudios sintéticos
Alex C Bissember1, Anna Levina, Gregory C Fu
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|August 22, 2012
Resumen
Este estudio utiliza la eliminación de beta-hidruro para la deshidrohalogenación catalizada por el paladio, produciendo de manera eficiente olefinas terminales a partir de bromuros de alquilo a temperatura ambiente. Este nuevo método se aplicó con éxito a una síntesis de (R) -mevalonolactona.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis es la catálisis.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- Las reacciones de acoplamiento cruzado catalizadas por paladio son fundamentales en la síntesis orgánica.
- La eliminación de beta-hidruro es a menudo una reacción secundaria indeseable en tales procesos.
- Los métodos eficientes para sintetizar las olefinas terminales son muy buscados.
Objetivo del estudio:
- Desarrollar un nuevo método catalizado por paladio para la deshidrohalogenación de bromuros de alquilo.
- Para utilizar el paso de eliminación de beta-hidruro típicamente no deseado como la transformación clave.
- Demostrar la utilidad de este método en una síntesis total formal y aclarar su mecanismo.
Principales métodos:
- Deshidrohalogenación catalizada por paladio de bromuros de alquilo utilizando ligandos de fosfina.
- Aplicación del método desarrollado a la síntesis de (R) -mevalonolactona.
- Investigaciones mecanicistas para determinar el paso determinante de la tasa e identificar los intermediarios clave.
Principales resultados:
- La reacción procede con un excelente rendimiento a temperatura ambiente.
- El método es tolerante con una variedad de grupos funcionales.
- Los estudios mecánicos revelaron que el paso que determina la velocidad es dependiente del sustrato y que L(2) PdHBr no es un intermediario.
Conclusiones:
- Se ha desarrollado una nueva y eficiente deshidrohalogenación catalizada por paladio de bromuros de alquilo a olefinas terminales.
- El método ofrece una ruta práctica para la síntesis de olefinas y ha sido validado a través de una síntesis total formal.
- Las ideas mecanicistas proporcionan una comprensión más profunda de las vías de reacción catalizadas por el paladio.
![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
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