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Inesperada activación de Ar-X inducida por H2O con trifluorometilepalladio (II) arilos
Vladimir V Grushin1, William J Marshall
1Central Research and Development, E.I. DuPont de Nemours & Co., Inc., Experimental Station, Wilmington, Delaware 19880-0328, USA. vlad.grushin-1@usa.dupont.com
Journal of the American Chemical Society
|April 6, 2006
Resumen
Las trazas de agua activan los complejos de paladio para el acoplamiento fenilo-haluro, formando bifenilo. Este proceso implica la reducción del paladio a paladio, crucial para la activación de enlaces de haluro de fenilo y la posterior formación de productos.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis es la catálisis.
- Coordinación Química de la Coordinación
Sus antecedentes:
- Los complejos de paladio son catalizadores vitales en la síntesis orgánica.
- Comprender los mecanismos de activación de los complejos de paladio es clave para desarrollar sistemas catalíticos eficientes.
- Los ligandos trifluorometilo y arilo en el paladio pueden influir en la reactividad.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos complejos de paladio (II) con ligandos de difosfina.
- Para investigar la activación de enlaces fenil-haluro por estos complejos.
- Para aclarar el papel del agua en el ciclo catalítico.
Principales métodos:
- Síntesis y caracterización completa de los complejos [{L-L) Pd{Ar}{CF3}.
- Investigación de las reacciones de activación del haluro de fenilo en condiciones variables.
- Estudios mecanicistas que incluyen análisis cinético e identificación de productos intermedios.
Principales resultados:
- Se sintetizaron con éxito nuevos complejos de paladio (II) con los ligandos dppe, dppp y tmeda.
- [dppePdPhCF3)] demostró la activación del fenil-ioduro y el fenil-cloruro para producir bifenil.
- Se encontraron trazas de agua que son esenciales para la reacción, promoviendo la reducción de PdII a Pd0 catalíticamente activo.
Conclusiones:
- El agua juega un papel crítico en el inicio de la catálisis mediante la reducción de Pd(II) a Pd(0).
- La reacción procede a través de pasos de transmesación y eliminación reductiva.
- Se propusieron vías alternativas que involucran transferencia de alfa-F e hidrólisis para la reducción inducida por el agua.
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