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Metátesis de cierre de anillo asistido por quelato: una estrategia para acelerar la macrociclosis a temperaturas
Carolyn S Higman1, Daniel L Nascimento1, Benjamin J Ireland1
1Center for Catalysis Research & Innovation, and Department of Chemistry and Biomolecular Sciences, University of Ottawa , Ottawa, Canada K1N 6N5.
Journal of the American Chemical Society
|January 19, 2018
Resumen
Los nuevos catalizadores de rutenio con quelatos hemilabílicos aceleran la metástasis de cierre de anillo para la síntesis de macrociclos. Este enfoque supera los desafíos de la oligomerización y mejora los rendimientos de moléculas complejas.
Área de la Ciencia:
- Química orgánica
- Catálisis
- Ciencias macromoleculares
Sus antecedentes:
- La metátesis de cierre de anillo (RCM) es crucial para la síntesis de macrociclos utilizados en productos farmacéuticos y fragancias.
- La oligomerización es una reacción secundaria común en RCM, reduciendo los rendimientos objetivo.
- Los catalizadores de rutenio existentes (Ru-NHC) pueden convertir oligómeros pero sufren de descomposición, lo que limita la eficiencia.
Objetivo del estudio:
- Desarrollar nuevos catalizadores de rutenio para una macrociclado eficiente a través de RCM.
- Para abordar la descomposición del catalizador y mejorar la selectividad en las reacciones RCM.
- Investigar el papel de los quelatos hemilabiles en la mejora de la actividad catalítica.
Principales métodos:
- Síntesis de nuevos catalizadores de rutenio que incorporan un quelato de o-dianilina (ODA) hemilabil.
- Aplicación de estos catalizadores en las reacciones RCM de varios dienes.
- Análisis de las tasas de reacción, los rendimientos y la selectividad, con un enfoque en la macrociclado frente a la oligomerización.
Principales resultados:
- Los nuevos catalizadores Ru-NHC-ODA aceleran significativamente la macrociclación, especialmente para los dienos con sitios polares de enlace de hidrógeno.
- Estos catalizadores demuestran una estabilidad mejorada, inhibiendo potencialmente la descomposición durante la metástasis.
- Se logró una macrociclización rápida de dienes conformacionalmente flexibles a temperatura ambiente, superando a los sistemas Ru-NHC anteriores.
Conclusiones:
- La incorporación de quelatos ODA hemilabílicos en catalizadores Ru-NHC mejora la eficiencia de la RCM para la síntesis de macrociclos.
- Los nuevos catalizadores ofrecen una solución prometedora para superar los problemas de oligomerización y descomposición del catalizador.
- Este trabajo avanza en los métodos catalíticos para la producción de valiosos compuestos macrocíclicos.
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