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La alfa-ariación catalizada por el paladio de los ésteres
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|August 17, 2001
Resumen
Un novedoso método catalizado con un solo recipiente de paladio permite la alfa-ariación de ésteres utilizando bromuros de arilo y cloruros. Esta síntesis eficiente produce importantes derivados de fármacos y crea centros de carbono cuaternarios.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis por catálisis.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- Las reacciones de acoplamiento cruzado catalizadas por paladio son cruciales en la síntesis orgánica.
- Los métodos eficientes para la alfa-arilación de ésteres son muy buscados para la construcción de moléculas complejas.
Objetivo del estudio:
- Desarrollar un procedimiento sencillo y eficiente de una sola olla para la alfa-ariación intermolecular catalizada por paladio de ésteres.
- Explorar el alcance y las limitaciones del método desarrollado para sintetizar compuestos valiosos.
Principales métodos:
- Se utiliza el acetato de paladio (Pd(OAc) 2 o tris ((dibenzilideneacetona) dipalladio ((0) (Pd2 ((dba) 3) como catalizadores.
- Se emplean grandes fosfinas o-bifenil ricas en electrones como ligandos.
- Se utilizó litio bis ((trimethylsilyl) amide (LiHMDS) como base para la reacción.
Principales resultados:
- Se obtienen altos rendimientos y selectividades para la monoariación de varios ésteres con bromuros de arilo a temperatura ambiente o 80°C.
- Se han sintetizado con éxito los ésteres tert-butilicos del naproxeno (79% de rendimiento) y del flurbiprofeno (86% de rendimiento).
- Demostró la actividad del sistema catalizador con cloruros de arilo y la formación de centros cuaternarios utilizando enolados de éster trisubstituidos.
Conclusiones:
- El procedimiento de un solo bote desarrollado ofrece una ruta simple y efectiva para la alfa-arilación de ésteres.
- El método proporciona acceso a importantes derivados de fármacos antiinflamatorios no esteroideos y arquitecturas moleculares complejas.
- El sistema catalítico muestra una amplia aplicabilidad, incluido el uso de cloruros de arilo y la síntesis de compuestos estéricamente obstaculizados.
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