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Epoxidación asimétrica de alquenos catalizados por un complejo de cobalto
Qianwen He1, Mao-Ping Pu1, Zheng Jiang1
1Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China.
Journal of the American Chemical Society
|July 5, 2023
Resumen
Los investigadores desarrollaron un nuevo catalizador quiral de cobalto para la epoxidación enantioselectiva de alquenos. Este avance supera el desafío de la "pared oxo", permitiendo una síntesis asimétrica eficiente con un ligando quiral único de N, N-dióxido.
Área de la Ciencia:
- Química organometálica
- Catálisis asimétrica
- Síntesis orgánica
Sus antecedentes:
- Se establecen catalizadores quirales no hémicos de manganeso y hierro-oxígeno para la epoxidación de alquenos.
- Los catalizadores quirales de cobalto-oxígeno están poco desarrollados para esta transformación debido a la
Objetivo del estudio:
- Informar sobre el primer complejo quiral de cobalto para la epoxidación enantioselectiva de alquenos trisubstituidos.
- Investigar el papel de un ligando quiral de N,N'-dióxido basado en tetraoxígeno en la epoxidación catalizada por cobalto.
Principales métodos:
- Epoxidación enantioselectiva utilizando el PhIO como oxidante.
- Estudios espectroscópicos (HRMS, UV-vis) y mediciones de la sensibilidad magnética.
- Cálculos de la teoría funcional de la densidad (DFT) y estudios cinéticos.
Principales resultados:
- Un complejo quiral de cobalto catalizó con éxito la epoxidación enantioselectiva de alceno cíclico y acíclico trisubstituido.
- Se confirmó la formación de un cuarteto de tautómero Co ((III) -oxilo como la especie activa Co-O.
- El ligando quiral N,N'-dióxido fue crucial para la formación intermedia y la transferencia de oxígeno enantioselectiva.
Conclusiones:
- El catalizador de cobalto quiral desarrollado supera efectivamente la limitación de la pared oxo.
- El estudio aclara el mecanismo y el origen de la enantioselectividad en la epoxidación catalizada por cobalto.
- Este trabajo abre nuevas vías para los catalizadores quirales de cobalto en síntesis asimétrica.
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