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Síntesis enantioselectiva mediada por cobalto de los dienos C(2) y C(1)

W Christopher Boyd¹, Mark R Crimmin, Lauren E Rosebrugh

¹Department of Chemistry, University of California, Berkeley, California 94720, United States.

Journal of the American Chemical Society

|November 2, 2010

Resumen

Este estudio informa de la funcionalización asimétrica C-H de alquenos utilizando un catalizador de cobalto y bases quirales. Este método permite la síntesis enantioselectiva de valiosos ligandos de dieno con alta selectividad.

Área de la Ciencia:

Química orgánica es la química orgánica.
Química organometálica Química orgánica de los metales.
Catalización asimétrica por catálisis asimétrica.

Sus antecedentes:

La funcionalización C-H es una transformación clave en la síntesis orgánica.
La catálisis asimétrica permite la síntesis de compuestos enantioméricamente puros.
El norborneno y el norbornadieno son alquenos cíclicos versátiles para la funcionalización.

Objetivo del estudio:

Desarrollar un nuevo método para la funcionalización asimétrica C-H de norborneno y norbornadieno.
Para utilizar un complejo de cobalto-nitrosilo como un intermediario reactivo.
Para lograr la síntesis enantioselectiva de los ligandos de dieno simétricos C(2) y C(1).

Principales métodos:

Reacción de funcionalización C-H asimétrica mediada por [{η(5)-((t) BuMe(2) Si) C(5) H(4)}Co(NO) ((2) ].
Uso de una nueva mezcla de base quiral de sales de amonio enantiopuro y NaHMDS.
Aplicación para la desimetrización de los alquenos C (((s)).

Principales resultados:

Se logró una alta regioselectividad (3.7-20:1 anti/syn) en la funcionalización.
Se observó una diastereoselectividad casi perfecta (>99:1 dr).
Se obtuvo una alta enantioselectividad (90-96% ee) para los ligandos de dieno sintetizados.

Conclusiones:

El método desarrollado proporciona un acceso eficiente a los ligandos de dieno enriquecidos enantioméricamente.
Este trabajo demuestra una aplicación novedosa de la funcionalización asimétrica C-H para la desimetrización de alceno.
La metodología ofrece una poderosa herramienta para construir moléculas quirales complejas.

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