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C ((sp2) -H Borilación de arenas fluoradas utilizando un precatalizador de cobalto estable en el aire: la
Jennifer V Obligacion1, Máté J Bezdek1, Paul J Chirik1
1Department of Chemistry, Princeton University , New Jersey 08544, United States.
Journal of the American Chemical Society
|February 1, 2017
Resumen
Los nuevos catalizadores de cobalto logran una alta selectividad orto-fluoro en la borilación C ((sp2) -H de arenas fluoradas. Este avance permite una síntesis eficiente del medicamento antiinflamatorio flurbiprofeno.
Área de la Ciencia:
- Química organometálica
- Catálisis
- Química orgánica sintética
Sus antecedentes:
- La borilación C ((sp2) -H es una reacción crucial en la síntesis orgánica.
- El logro de la selectividad del sitio, especialmente de orto-a-fluoro, en la borilación de arenas fluoradas es un desafío.
- Los catalizadores de metales preciosos a menudo dependen de grupos de dirección, lo que limita el alcance del sustrato.
Objetivo del estudio:
- Desarrollar nuevos catalizadores de cobalto para la borilación selectiva del sitio C ((sp2) -H de los arenos fluorados.
- Para lograr una alta selectividad de orto-fluoruro, superando los efectos tradicionales del grupo de dirección.
- Para demostrar la utilidad de estos catalizadores en la síntesis de valiosos compuestos farmacéuticos.
Principales métodos:
- Síntesis y caracterización de cobalto (III) dihidruro de borilo (1) y cobalto (II) bis (pivalato) (2) complejos con el ligando 4-Me- (iPrPNP).
- Evaluación de la actividad catalítica y de la selectividad en la borilación C ((sp2) -H de varios arenes fluorados.
- Evaluación de la tolerancia del grupo funcional y la compatibilidad con otros reactivos como las aminas y los hidrosilanos.
Principales resultados:
- Desarrollo de catalizadores de cobalto mejorados electrónicamente que exhiban una alta selectividad orto-fluoro en la borilación C ((sp2) -H.
- Tanto los catalizadores de cobalto (III) sensibles al aire como los de cobalto (II) estables al aire demostraron una amplia tolerancia de grupo funcional.
- La selectividad observada se mantuvo incluso en presencia de dimetilamina bencílica e hidrosilanos, superando a los catalizadores de metales preciosos.
- El sistema catalítico fue aplicado con éxito a la síntesis eficiente de flurbiprofeno.
Conclusiones:
- Los nuevos catalizadores de cobalto ofrecen una selectividad de sitio mejorada electrónicamente para la borilación C ((sp2) -H de los arenos fluorados.
- Estos catalizadores proporcionan una poderosa alternativa a los sistemas de metales preciosos, superando las limitaciones asociadas con los grupos de dirección.
- La metodología desarrollada facilita la síntesis práctica de moléculas importantes, incluido el medicamento antiinflamatorio flurbiprofeno.
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