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Ciclizaciones enantioselectivas de las sililoxieninas catalizadas por complejos de fosfina de metales catiónicos

Jean-François Brazeau¹, Suyan Zhang, Ignacio Colomer

¹Department of Chemistry, University of California, Berkeley, California 94720, USA.

Journal of the American Chemical Society

|February 3, 2012

Resumen

Los ligandos quirales de la fosfina permiten la ciclización enantioselectiva de las sililoxieninas utilizando la catálisis del paladio y el oro. Estos métodos producen ciclopentanos quirales y derivados bicíclicos con altas estereoselectividades.

Área de la Ciencia:

Química orgánica es la química orgánica.
La catálisis es la catálisis.
Síntesis asimétrica de síntesis.

Sus antecedentes:

La catálisis de metales de transición es crucial para la construcción de moléculas orgánicas complejas.
La síntesis enantioselectiva es vital para los productos farmacéuticos y los productos químicos finos.
Las sililoxieneninas son versátiles bloques de construcción para las reacciones de ciclización.

Objetivo del estudio:

Desarrollar métodos complementarios de ciclización enantioselectiva para las silylloxyenynes.
Explorar el uso de ligandos quirales de fosfina en la catálisis del paladio y el oro.
Para sintetizar ciclopentano quiral y derivados bicíclicos con alto estereocontrol.

Principales métodos:

Ciclización catalizada por el paladio de 1,6-sililoxieneninas con alquinas terminales.
Ciclización catalizada por oro catiónico de 1,6- y 1,5-sililoxieneninas con alquinas internas.
Ciclización en tándem que involucra la α,β-insaturación y la ciclización de sililoxi-1,3-dieno-7-ynes.

Principales resultados:

Se obtienen altas enantioselectividades (hasta el 91% ee) en reacciones catalizadas por el paladio.
Excelente exceso enantiomérico (hasta 94% ee) obtenido en reacciones catalizadas por oro.
Altas diastereoselectividades (>20:1 dr) y enantioselectividades (hasta 99% ee) para los derivados cíclicos.

Conclusiones:

Desarrolló métodos enantioselectivos eficientes para la ciclización de silylloxyenyne.
Demostró la utilidad de los ligandos quirales de la fosfina tanto en la catálisis del paladio como en la del oro.
Amplió el alcance para incluir ciclizaciones en tándem y síntesis de complejas estructuras bicíclicas.

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