Notable regi- y estereodivergencia controlada por ligandos en la hidrosilación intermolecular de alquinas internas:
Shengtao Ding1, Li-Juan Song, Lung Wa Chung
1Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong SAR, China.
Journal of the American Chemical Society
|August 27, 2013
Resumen
Los catalizadores de rutenio permiten la hidrosilación controlada por ligando de los alquinos, produciendo diversos vinildisilanos. El bulto estérico y los ligandos catalizadores dictan la región opuesta y la estereoselectividad en este eficiente método sintético.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Química orgánica sintética y orgánica.
Sus antecedentes:
- Las hidrosilaciones intermoleculares de alquinas internas son transformaciones sintéticas cruciales.
- Lograr una alta regionalidad y estereoselectividad en estas reacciones sigue siendo un desafío.
- El diseño de ligandos es clave para controlar los resultados catalíticos.
Objetivo del estudio:
- Para revelar las primeras hidrociliaciones intermoleculares regionales y estereodivergentes altamente eficientes controladas por ligando de alquinas internas.
- Para explorar la actividad catalítica de los complejos catiónicos de rutenio, específicamente [Cp*Ru(MeCN) 3+ y [CpRu(MeCN) 3+].
- Investigar el papel de los grupos sililo y los ligandos catalizadores en el control de la selectividad.
Principales métodos:
- Catálisis utilizando complejos catiónicos de rutenio ([Cp*Ru(MeCN) 3) + y [CpRu(MeCN) 3) +).
- Hidrosilación intermolecular de las alquinas silílicas.
- Cálculos de la Teoría Funcional de Densidad (DFT) para elucidar los mecanismos de reacción.
- Validación experimental de las predicciones teóricas.
Principales resultados:
- Descubrimiento de la hidrosilación intermolecular controlada por ligandos, regio y estereodivergente de las alquinas internas.
- Formación de vinildisilanos con excelente y opuesta regio- y estereoselectividad (α anti vs. β sin adición) dependiendo del ligando catalizador de rutenio (Cp* vs. Cp).
- Demostración de que los grupos de enmascaramiento de sililo proporcionan volumen estérico para la selectividad y permiten la derivación versátil de productos.
- Los cálculos de DFT revelaron un mecanismo que involucra la hidrometalización oxidativa, la isomerización y la migración silílica reductiva.
Conclusiones:
- El efecto estérico de los ligandos y los sustituyentes alquinos gobierna críticamente la regioselectividad y la estereoselectividad.
- La interacción entre el grupo sililo en el alquino y el ligando del catalizador de rutenio dicta la estereodivergencia observada.
- Este trabajo proporciona una plataforma versátil para sintetizar bloques de construcción valiosos a través de la hidrosilación controlada.
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