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Acoplamiento oxidativo en tándem catalizado por el hierro y anulación: un enfoque eficiente para construir

Xingwei Guo¹, Rong Yu, Haijun Li

¹Department of Chemistry, Renmin University of China, Beijing 100872, China.

Journal of the American Chemical Society

|November 11, 2009

Resumen

Un nuevo método sintetiza eficientemente benzofuranos polisubstituidos a partir de fenoles y ésteres beta-ceto utilizando hexahidrato y peróxido de cloruro de hierro (III). Esta reacción evita la escisión de los enlaces aromáticos C-H en las etapas que determinan la velocidad.

Área de la Ciencia:

Química orgánica es la química orgánica.
Metodología sintética de la metodología sintética.
La catálisis de la catálisis.

Sus antecedentes:

La condensación de Pechmann generalmente produce cumarinas a partir de fenoles y ésteres beta-ceto.
El desarrollo de rutas sintéticas eficientes y novedosas para compuestos heterocíclicos como los benzofuranos es crucial en la química orgánica.

Objetivo del estudio:

Desarrollar un método novedoso y eficiente para la síntesis de benzofuranos polisubstituidos.
Para investigar el mecanismo de reacción y el papel del catalizador de hierro.

Principales métodos:

Reacción de fenoles simples con ésteres beta-ceto en presencia de FeCl3x6H2O y peróxido de di-tert-butilo.
Elucidación estructural de productos utilizando cristalografía de rayos X.
Estudios del efecto isotópico cinético (KIE) para sondear el mecanismo de reacción.

Principales resultados:

Se sintetizó una variedad de benzofuranos polisubstituidos con rendimientos de moderados a excelentes.
La anulación específica de la región fue confirmada por cristalografía de rayos X.
Los experimentos de KIE (k ((H) / k ((D) = 1.0 +/- 0.1) indicaron que la escisión de los enlaces aromáticos C-H no es determinante para la velocidad.
El catalizador de hierro exhibió un comportamiento dicotómico: catalizador de metales de transición en acoplamiento oxidativo y ácido de Lewis en condensación.

Conclusiones:

FeCl(3) x 6 H(2) O y peróxido de di-tert-butilo proporcionan un sistema eficaz para la síntesis de benzofuranos.
El mecanismo implica distintas funciones catalíticas para las especies de hierro.
Se propuso un mecanismo de reacción tentativo, respaldado por síntesis intermedia y datos de KIE.

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