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Cascada de sustitución de radicales Heck/Alílica interrumpida de tres componentes que incluye alquilbromuros no

Huan-Ming Huang¹, Peter Bellotti¹, Philipp M Pflüger¹

¹Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany.

Journal of the American Chemical Society

|May 8, 2020

Resumen

Este estudio introduce un nuevo acoplamiento radical catalizado por el paladio para la eficiente desfuncionalización de dienos utilizando bromuros de alquilo no activados. Este método supera las limitaciones en la síntesis de moléculas complejas con múltiples centros estereogénicos.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

La síntesis de moléculas complejas con centros estereogénicos es un reto.
Las reacciones en cascada catalítica son valiosas para construir la complejidad molecular.
Las reacciones de tipo Heck con haluros de alquilo no activados están limitadas por la eliminación de beta-hidruro.

Objetivo del estudio:

Desarrollar un método general y práctico para la desfuncionalización de 1,3-dienes no activados.
Para superar las limitaciones de la eliminación de beta-hidruro en reacciones de tipo Heck.
Permitir la construcción de bonos secuenciales C{\displaystyle C} -C{\displaystyle C} y C{\displaystyle C} -X con un amplio alcance.

Principales métodos:

Una estrategia de acoplamiento radical de tres componentes, catalizada por el paladio.
Medición de luz visible que permite una secuencia de sustitución Heck/allilic interrumpida.
Utilizando bromuros de alquilo no activados y diversos nucleófilos (basados en N, O, S y C).

Principales resultados:

Se ha conseguido la desfuncionalización selectiva de 1,3-dienos no activados (> 130 ejemplos).
Se ha demostrado una elevada estereoselectividad (en su mayoría > 95:5 E/Z) y regioselectividad (> 20:1 rr).
Construcción eficiente de enlaces C(sp3) -C(sp3) y C-X con una amplia tolerancia de grupo funcional.

Conclusiones:

El método desarrollado supera las limitaciones anteriores en el acoplamiento de haluros de alquilo.
Esta estrategia proporciona una ruta versátil para éteres complejos, sulfonas y aminas terciarias.
El enfoque es práctico, escalable (demostrado en escala de gramos) y ampliamente aplicable.

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