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Fluoración en cáscara abierta de bromuros de alquilo: Selectividad inesperada en un proceso de cadena mediada por

Gabrielle H Lovett¹, Shuming Chen², Xiao-Song Xue²

¹Merck Center for Catalysis , Princeton University , Princeton , New Jersey 08544 , United States.

Journal of the American Chemical Society

|November 28, 2019

Resumen

Este estudio introduce un nuevo método para la fluoración de bromuros de alquilo utilizando radicales silílicos y luz. El proceso reemplaza selectivamente el bromo por el flúor, ofreciendo una herramienta versátil para crear estructuras químicas importantes.

Área de la Ciencia:

Química orgánica
Química sintética
La fotoquímica

Sus antecedentes:

La fluoración es crucial en la química medicinal y los productos agroquímicos.
Los métodos de fluoración existentes a menudo carecen de selectividad o requieren condiciones duras.
El desarrollo de estrategias de fluoración novedosas y eficientes es un desafío continuo.

Objetivo del estudio:

Desarrollar una nueva estrategia basada en radicales para la fluoración de bromuros de alquilo.
Para lograr la abstracción selectiva de átomos de halógeno de los bromuros de alquilo utilizando radicales sililo y fotosensibilización.
Explorar la utilidad de este método para la síntesis de valiosos compuestos fluorados.

Principales métodos:

Utilizando la abstracción de átomos de halógeno mediada por el radical silílico.
Empleando la fotosensibilización de la benzofenona para iniciar reacciones radicales.
Realización de estudios mecanicistas y computacionales para aclarar la selectividad.
Probando la tolerancia del grupo funcional del protocolo.

Principales resultados:

Se desarrolló con éxito una nueva estrategia radical para la fluoración de bromuro de alquilo.
Se logró la abstracción selectiva de átomos de halógeno de los bromuros de alquilo, anulando la formación prevista de enlaces Si-F.
Se identificó un mecanismo de cadena radical con selectividad cinética para la abstracción de Si-Br.
El protocolo libre de metales de transición demostró una amplia tolerancia del grupo funcional.

Conclusiones:

El método desarrollado proporciona un enfoque nuevo, selectivo y versátil para la fluoración de bromuro de alquilo.
Esta estrategia complementa las tecnologías de fluoración existentes y tolera diversos grupos funcionales.
El sistema se aplicó con éxito para generar motivos de gemas difluoradas relevantes para los agentes medicinales y agroquímicos.

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