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Eficientes y prácticas cicloadiciones catalizadas por Ag entre las aryliminas y el diene de Danishefsky

Nathan S Josephsohn¹, Marc L Snapper, Amir H Hoveyda

¹Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.

Journal of the American Chemical Society

|April 3, 2003

Resumen

Este estudio introduce una eficiente reacción asimétrica de cicloadición catalizada por plata utilizando las iminas Danishefsky dieno y arilo. El método logra una alta enantioselectividad y rendimiento, utilizando un ligando quiral fácilmente preparado y ofreciendo opciones libres de disolventes.

Área de la Ciencia:

Química orgánica es la química orgánica.
Catalización asimétrica por catálisis asimétrica.
Reacciones de adición por ciclo Reacciones de adición por ciclo.

Sus antecedentes:

El dieno de Danishefsky es un reactivo versátil en la síntesis orgánica.
La síntesis asimétrica de los conductos ciclóricos es crucial para el desarrollo farmacéutico.
Se necesitan métodos catalíticos eficientes para las cicloadiciones enantioselectivas.

Objetivo del estudio:

Desarrollar una adición asimétrica eficiente catalizada por Ag del dieno de Danishefsky a las iminas de arilo.
Para lograr una alta enantioselectividad y rendimiento en la formación de conductos de carga cíclica.
Explorar las condiciones prácticas de reacción, incluyendo protocolos libres de disolventes y tolerantes al aire.

Principales métodos:

Utilizó una reacción asimétrica de cicloadición catalizada por plata (Ag).
Empleó el dieno de Danishefsky y varias iminas de arilo como sustratos.
Desarrolló y utilizó un ligando quiral fácilmente preparado derivado de materiales baratos como i-Leu.
Reacciones investigadas a bajas temperaturas (4 grados C) con baja carga del catalizador (0,1-1 mol %).

Principales resultados:

Se logró un alto exceso enantiomérico (ee) de ≥89% para los conductos de carga cíclica.
Se obtuvieron altos rendimientos aislados de ≥85%.
Reacciones exitosas demostradas en condiciones libres de disolventes y en el aire.
Informó de un catalizador quiral reciclable de primera generación con cinco ciclos exitosos.

Conclusiones:

Se ha establecido un método eficiente y práctico de cicloadición asimétrica catalizada por Ag.
El ligando quiral desarrollado y el sistema catalítico son efectivos para la síntesis de valiosos conductos de carga cíclica.
El potencial de los catalizadores reciclables y las condiciones de reacción simplificadas mejoran la aplicabilidad de esta metodología.

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