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Catalizadores mejorados de rutenio para la metátesis de olefinas Z-selectivas
Benjamin K Keitz1, Koji Endo, Paresma R Patel
1Arnold and Mabel Beckman Laboratories of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|November 22, 2011
Resumen
Nuevos catalizadores de rutenio permiten la metátesis Z-selectiva de las olefinas. Los ligandos de tipo nitrato mejoran significativamente la actividad y la selectividad, logrando altos números de rotación para aplicaciones industriales.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis es la catálisis.
- Síntesis orgánica La síntesis orgánica.
Sus antecedentes:
- La metátesis de las olefinas es una poderosa reacción de formación de enlaces carbono-carbono.
- Lograr una alta selectividad Z en la metátesis de olefinas sigue siendo un desafío.
- Los catalizadores de rutenio son ampliamente utilizados, pero requieren optimización para selectividades específicas.
Objetivo del estudio:
- Para sintetizar y evaluar nuevos catalizadores de rutenio activados por C-H para la metátesis de olefinas Z-selectivas.
- Para investigar el impacto de las modificaciones de ligandos en el rendimiento del catalizador.
- Explorar el potencial de estos catalizadores en la síntesis de compuestos industrialmente relevantes.
Principales métodos:
- Síntesis de nuevos complejos de rutenio con carbenos y ligandos carboxilatos N-heterocíclicos modificados.
- Evaluación del rendimiento del catalizador en varias reacciones de metástasis de olefinas, incluida la metástasis cruzada.
- Variación sistemática de los tipos de ligando (monodentado frente a bidentado, carboxilato frente a nitrato).
Principales resultados:
- La modificación del ligando impacta significativamente la actividad del catalizador y la selectividad Z.
- La sustitución de bidentato por ligandos monodentados disminuyó el rendimiento.
- Los ligandos de tipo nitrato demostraron una actividad y selectividad superiores en comparación con los carboxilatos.
- Se lograron cifras de rotación cercanas a 1000 para las reacciones de metatesis cruzada.
Conclusiones:
- Se han desarrollado nuevos catalizadores de rutenio activados por C-H con mejorada selectividad Z.
- Los ligandos de tipo nitrato son clave para mejorar la actividad y la selectividad de la metástasis.
- Estos catalizadores son prometedores para la síntesis eficiente de productos químicos valiosos.
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