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Bromocloración catalítica, regioselectiva, diastereoselectiva y enantioselectiva de sistemas insaturados habilitada

Alexandra E Lubaev¹, Manjula D Rathnayake¹, Favour Eze¹

¹Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States.

Journal of the American Chemical Society

|July 12, 2022

Resumen

Un nuevo método catalizado por bases de Lewis permite la bromocloración selectiva de compuestos insaturados utilizando cloruro de tionio y un catalizador mínimo. Este enfoque libre de metales ofrece una alta regioselectividad y diastereoselectividad para varios alquenos y alquinas.

Área de la Ciencia:

Química orgánica
Catálisis
Reacciones de halogenación

Sus antecedentes:

Los métodos tradicionales de bromocloración a menudo carecen de selectividad o requieren condiciones duras.
El desarrollo de sistemas catalíticos eficientes y selectivos para la halogenación sigue siendo un desafío clave en la síntesis orgánica.

Objetivo del estudio:

Introducir una nueva estrategia catalizada por bases de Lewis para la bromocloración de sistemas insaturados.
Para lograr una alta quimio, regio y diastereoselectividad en un proceso catalítico libre de metales.

Principales métodos:

Utilizando el cloruro de tionio como fuente de cloruro latente.
Utilizando cantidades catalíticas (1 mol %) de trifenilfosfina u óxido de trifenilfosfina como activadores de la base de Lewis.
Exploración de las variaciones en los reactivos halogenados para la instalación precisa de Br, Cl e I.

Principales resultados:

Se ha conseguido una bromocloración catalítica libre de metales de alquenos y alquinas con una excelente selectividad del sitio.
Se ha demostrado una elevada regioselectividad y diastereoselectividad (> 20:1) para los bromocloruros vicinales.
Se demostró la bromocloración enantioselectiva de chalcones utilizando una base quiral de Lewis (hasta una relación enantiomérica de 92: 8).

Conclusiones:

El método desarrollado proporciona una vía novedosa, eficiente y altamente selectiva para los bromocloruros vecinos.
La estrategia es versátil, permitiendo la instalación precisa de varios halógenos y la síntesis enantioselectiva.
Este enfoque catalizado por bases de Lewis ofrece una alternativa valiosa a las metodologías de bromocloración existentes.

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