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Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization
Published on: November 29, 2018
Catalizadores a base de Ru fácilmente accesibles y fácilmente modificables para la polimerización eficiente y
R Kashif M Khan1, Sebastian Torker, Amir H Hoveyda
1Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, United States.
Journal of the American Chemical Society
|July 5, 2013
Resumen
Nuevos catalizadores de rutenio con ligandos de metiolato permiten una metátesis de olefinas altamente selectiva por Z. Estos eficientes catalizadores funcionan en condiciones suaves con bajas cargas, ofreciendo una ruta más simple para complejas transformaciones químicas.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis es la catálisis.
- La ciencia de los polímeros es la ciencia de los polímeros.
Sus antecedentes:
- La metátesis de olefinas es una poderosa reacción de formación de enlaces carbono-carbono.
- Lograr una alta selectividad Z en la metástasis sigue siendo un desafío significativo.
- Los catalizadores basados en rutenio son ampliamente utilizados, pero a menudo carecen de un control estereoquímico preciso.
Objetivo del estudio:
- Desarrollar nuevos catalizadores basados en rutenio para la metatesis de olefinas Z-selectivas eficientes.
- Para investigar el rendimiento de estos catalizadores en la polimerización de la metátesis de apertura de anillo (ROMP) y la apertura de anillo / metátesis cruzada (ROCM).
- Aclarar las características estructurales y mecánicas que contribuyen al rendimiento del catalizador.
Principales métodos:
- Síntesis de nuevos complejos de Ru-dithiolato a partir de precursores comerciales.
- Evaluación de la eficiencia del catalizador y la selectividad Z en las reacciones ROMP y ROCM.
- Caracterización utilizando cálculos de difracción de rayos X y teoría funcional de la densidad (DFT).
Principales resultados:
- Síntesis de un solo paso de catalizadores de Ru-dithiolato en un rendimiento del 68-82%.
- Z-selectividad excepcional (93:7 a >98:2 Z:E) alcanzada bajo condiciones suaves (22 °C).
- Alta actividad catalítica con bajas cargas de catalizador (0,002 mol %) y altos números de rotación (hasta 43.000).
Conclusiones:
- Los catalizadores de Ru-dithiolato diseñados racionalmente proporcionan una metatesis de olefinas eficiente y altamente Z-selectiva.
- Estos catalizadores ofrecen simplicidad operativa y alta actividad sin una purificación estricta del sustrato.
- Los datos DFT y de rayos X proporcionan información sobre el diseño y el mecanismo del catalizador.
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