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La borilación para-C-H de derivados del benceno por un catalizador de iridio voluminoso

Yutaro Saito¹, Yasutomo Segawa¹, Kenichiro Itami¹

¹†Graduate School of Science, ‡JST, ERATO, Itami Molecular Nanocarbon Project, and §Institute of Transformative Bio-molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan.

Journal of the American Chemical Society

|April 11, 2015

Resumen

Un nuevo catalizador de iridio permite la borilación aromática C-H altamente para-selectiva de los derivados del benceno. Este método controlado estérico logra hasta un 91% de para-selectividad, ofreciendo una síntesis predecible para productos farmacéuticos y materiales.

Área de la Ciencia:

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

Sus antecedentes:

La borilación aromática C-H es una transformación sintética clave.
Los catalizadores tradicionales de iridio carecen de regioselectividad para los benzenos monosubstituidos, favoreciendo a los metaproductos.
El desarrollo de catalizadores selectivos para la parafuncionalización sigue siendo un desafío.

Objetivo del estudio:

Desarrollar un método de borilación aromática C-H altamente para-selectivo.
Investigar un nuevo sistema de catalizador de iridio para la funcionalización regioselectiva.
Para demostrar la utilidad del método en la síntesis de derivados de drogas.

Principales métodos:

Utilizó un nuevo catalizador de iridio con un ligando de difosfina voluminoso (Xyl-MeO-BIPHEP).
Investigó la borilación C-H de los benzenos monosubstituidos.
Se analizó la regioselectividad basada en las propiedades estéricas del sustrato y el catalizador.

Principales resultados:

Se logra hasta un 91% de para-selectividad en la borilación aromática C-H.
Se demostró que la para-selectividad aumenta con el volumen del sustituto, lo que indica un control estérico.
Se han sintetizado con éxito cinco derivados del caramifeno, un fármaco anticolinérgico.

Conclusiones:

El sistema catalizador [Ir(cod) OH]2/Xyl-MeO-BIPHEP proporciona una borilación C-H aromática para-selectiva y controlada estéricamente.
Este método ofrece una síntesis simplificada y predecible.
El sistema catalizador tiene aplicaciones potenciales en el descubrimiento farmacéutico y de materiales.

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