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Acoplamiento carbono-carbono de enlaces C(sp3)-F utilizando catálisis de aluminio
Weixing Gu1, Mason R Haneline, Christos Douvris
1Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA.
Journal of the American Chemical Society
|September 3, 2009
Resumen
Nuevos catalizadores permiten la defluoración alquilativa de los enlaces alifáticos C-F utilizando compuestos de alquila aluminio. Esta reacción selectiva convierte los bonos C-F en bonos C-Me con alta fidelidad.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química del flúor Química del flúor
- La catálisis de la catálisis.
Sus antecedentes:
- Los bonos alifáticos C-F generalmente no reaccionan.
- Los métodos existentes para la funcionalización de bonos C-F a menudo carecen de selectividad o requieren condiciones duras.
Objetivo del estudio:
- Desarrollar catalizadores eficientes y selectivos para la alquilación de enlaces alifáticos C-F.
- Para investigar el mecanismo y el alcance de esta nueva reacción de desfluoración alquilativa (AlkDF).
Principales métodos:
- Se utilizaron equivalentes de cationes de dialquilalumenio con aniones de hexabromocarborano como catalizadores.
- Empleó varios compuestos de alquilaluminio, incluidos el trimetilaluminio (Me(3) Al) y el trietilaluminio (Et(3) Al), como agentes alquiladores.
- Productos de reacción analizados utilizando técnicas analíticas estándar para determinar la conversión y la selectividad.
Principales resultados:
- Desarrolló catalizadores eficientes y de larga duración para la defluoración alquilativa (AlkDF) de enlaces C ((sp ((3)) -F.
- Se ha demostrado la conversión de alta fidelidad de los bonos C-F a los bonos C-Me utilizando Me(3)Al.
- Se observó que solo los bonos C(sp(3)) -F son reactivos, mientras que los bonos C(sp(2)) -F no se ven afectados.
- Identificó la hidrodefluoración como una vía competitiva con Et(3) Al, lo que sugiere una transferencia competitiva de hidruro versus alquilo.
- Demostró la capacidad de los compuestos de organoaluminio para tolerar el agua, simplificando las condiciones de reacción.
Conclusiones:
- Los catalizadores de dialquilalumenio ofrecen un método selectivo y eficiente para la defluoración alquilativa de enlaces alifáticos C-F.
- Este sistema catalítico proporciona ventajas sobre la activación de C-F no catalizada, incluidas mayores tasas y selectividad.
- La metodología es aplicable a varios sustratos que contienen enlaces alifáticos C-F, incluidos los monofluoroalcanes y los grupos CF3).
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