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Metátesis de enlace sigma inducida por Li+: arilo por intercambio de metilo en boro en un anión de
Zbynĕk Janousek1, Uwe Lehmann, Jakub Castulík
1Department of Chemistry and Biochemistry, University of Colorado at Boulder, Colorado, USA.
Journal of the American Chemical Society
|April 1, 2004
Resumen
Se observó una nueva reacción de metatesis de enlace sigma entre un derivado de carborato de litio y un arilsilano a 190°C. Esta reacción requiere cationes activos de litio y produce un anión carborato arilado, cuya estructura se aclara mediante cristalografía de rayos X.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química del boro en la química del boro
- Química del carborano Química del carborano
Sus antecedentes:
- Los carboranos son compuestos versátiles de clúster de boro con propiedades electrónicas y estructurales únicas.
- La metátesis de enlaces sigma es una herramienta poderosa para formar nuevos enlaces carbono-elemento.
- Comprender la reactividad de los derivados del carborano es crucial para desarrollar nuevas metodologías sintéticas.
Objetivo del estudio:
- Para investigar la reactividad de la metátesis de enlaces sigma de un derivado del monocarbadodecaborato de litio.
- Para explorar la influencia del contra-catión en la reacción de metatesis.
- Para caracterizar el producto de la reacción de arilación.
Principales métodos:
- Reacción a alta temperatura del derivado del monocarbadodecaborato de litio (1a) con el p-bromofeniltrimetilsilano.
- Cristalografía de rayos X para la determinación de la estructura del anión carborato arilado (2).
- Estudios comparativos utilizando sal de cesio (1b) y la adición de 12-corona-4.
Principales resultados:
- La metátesis formal del enlace sigma ocurrió a 190°C, produciendo tetrametilsilano y el anión carborato arilado.
- La reacción depende de la presencia de cationes Li+ activos, ya que falló con la sal de cesio o en presencia de un éter de corona.
- Se determinó con éxito la estructura de rayos X del anión carborato arilado.
Conclusiones:
- Los derivados del monocarbadodecaborato de litio pueden someterse a una metátesis de enlaces sigma con los arilsilanos.
- La presencia de cationes Li+ activos es esencial para esta reacción específica de metátesis.
- El estudio proporciona información sobre el mecanismo y el alcance de la funcionalización del carborano a través de la metátesis.
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