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Funcionalización de β-C-H asimétrico activado por luz visible de cetonas sustituidas por receptores con compuestos

Jiajia Ma¹, Anthony R Rosales², Xiaoqiang Huang¹

¹Fachbereich Chemie, Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35043 Marburg, Germany.

Journal of the American Chemical Society

|November 22, 2017

Resumen

Este estudio introduce un nuevo método para la funcionalización asimétrica de C-H utilizando luz visible y un catalizador de rodio. La reacción crea eficientemente moléculas complejas con alta estereoselectividad, avanzando la síntesis orgánica.

Área de la Ciencia:

Química orgánica
Catálisis
La fotoquímica

Sus antecedentes:

La síntesis asimétrica es crucial para los productos farmacéuticos y materiales.
El desarrollo de sistemas catalíticos eficientes para la funcionalización de C-H sigue siendo un reto.
La catálisis fotorredóxica con luz visible ofrece un enfoque sostenible para las transformaciones orgánicas.

Objetivo del estudio:

Desarrollar un nuevo método asimétrico de funcionalización β-C ((sp3)-H activado por luz visible.
Para utilizar un catalizador de ácido de Lewis estereogénico en rodio para un alto control estereogénico.
Explorar el mecanismo de reacción a través de estudios experimentales y computacionales.

Principales métodos:

Irradiación con luz visible de 2-acil imidazoles/piridinas con compuestos 1,2-dicarbonilo.
Catalización con un ácido de Lewis estereogénico en rodio hecho a medida.
Aislamiento y purificación del producto.
Análisis de estereoselectividad (determinación de dr y ee).
Investigaciones mecanicistas mediante métodos experimentales y computacionales.

Principales resultados:

Productos de formación de enlaces C-C de alto rendimiento (hasta el 99%).
Excelentes estereoselectividades (hasta >20:1 dr y >99% ee).
Identificación de un mecanismo de reacción que involucra el enolato de Rh fotoactivado, la transferencia de un solo electrón, la transferencia de protones y la recombinación radical-radical.

Conclusiones:

El método desarrollado proporciona una ruta eficiente y altamente estereoselectiva para la funcionalización β-C ((sp3) -H.
El diseño del catalizador y la activación de la luz visible son clave para lograr una alta enantioselectividad.
Las ideas mecanicistas allanan el camino para el diseño de nuevos sistemas catalíticos para la síntesis asimétrica.

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