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Síntesis enantioselectiva del ansa-zirconocenocenos
Matthew D LoCoco1, Richard F Jordan
1Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, USA.
Journal of the American Chemical Society
|October 28, 2004
Resumen
Los complejos quirales de zirconoceno fueron sintetizados con alto rendimiento y pureza enantiomérica utilizando nuevos reactivos ansa-bis-indenilo. Estos compuestos son valiosos para la catálisis asimétrica, con aplicaciones potenciales en la síntesis estereoselectiva.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis asimétrica.
- Química del zirconio Química del zirconio
Sus antecedentes:
- Los ligandos quirales son cruciales para la síntesis enantioselectiva.
- Los complejos de circonoceno son catalizadores ampliamente utilizados en la polimerización y la síntesis orgánica.
- El desarrollo de rutas eficientes para zirconocenos enantioméricamente puros es de gran interés.
Objetivo del estudio:
- Para sintetizar nuevos complejos quirales ansa-zirconoceno.
- Para investigar la utilidad de los nuevos reactivos de litio ansa-bis-indenilo.
- Para lograr altos rendimientos y exceso enantiomérico en la síntesis de estos complejos.
Principales métodos:
- Reacción de un complejo de zirconio bis-amida quiral quelado con reactivos de litio ansa-bis-indenilo.
- Aislamiento y purificación de los productos de ansa-zirconoceno resultantes.
- Conversión de un ansa-zirconoceno a su derivado dicloruro y recuperación del ligando quiral de diamina.
Principales resultados:
- La síntesis de dos nuevos ansa-zirconocenos, (S,S,R,R)-9a y (S,S,R,R)-9b, se logró con un rendimiento aislado de >95% y un exceso enantiomérico de >99%.
- Se obtuvo dicloruro enantioméricamente puro (S,S)-10b con un rendimiento del 91%.
- El ligando quiral de diamina se recuperó con éxito después de la reacción.
Conclusiones:
- El método desarrollado proporciona un acceso eficiente a los ansa-zirconocenos enantioméricamente puros.
- Los nuevos reactivos de litio ansa-bis-indenilo son socios de acoplamiento efectivos para los complejos quirales de zirconio.
- Estos zirconocenos quirales son candidatos prometedores para aplicaciones en catálisis asimétrica.
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