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Sustitución alilica enantioselectiva catalizada por iridio con soluciones acuosas de nucleófilos

Tobias Sandmeier¹, F Wieland Goetzke¹, Simon Krautwald¹

¹ETH Zürich , Vladimir-Prelog-Weg 3 , HCI, 8093 Zürich , Switzerland.

Journal of the American Chemical Society

|July 19, 2019

Resumen

La catálisis del iridio permite la sustitución alilica asimétrica utilizando nucleófilos inestables. Este método produce eficientemente diversos compuestos quirales con alta estereoselectividad.

Área de la Ciencia:

Química organometálica
Catálisis asimétrica
Química orgánica sintética

Sus antecedentes:

La sustitución alilica asimétrica es una herramienta poderosa para crear moléculas quirales.
El uso de nucleófilos inestables o volátiles en tales reacciones presenta desafíos significativos.
Los sistemas catalíticos bifásicos ofrecen ventajas únicas para el manejo de especies reactivas.

Objetivo del estudio:

Desarrollar un protocolo de sustitución alilico asimétrico catalizado por iridio.
Para permitir el uso de una amplia gama de nucleófilos inestables y/o volátiles.
Para lograr altos rendimientos y un excelente control estéreo en los productos.

Principales métodos:

El uso de un catalizador de iridio para reacciones asimétricas de sustitución de alelo.
Utilizando un sistema de reacción bifásico para acomodar diversos nucleófilos.
Caracterización de los productos mediante técnicas analíticas estándar (NMR, HPLC, etc.) Por ejemplo:

Principales resultados:

Aplicación exitosa de varios nucleófilos inestables: hidrazinas, metilamina, hidroperoxido de t-butilo, N-hidroxilamina, α-cloroacetaldehído y glutaraldehído.
Se obtuvieron altos rendimientos y enantioselectividades excelentes (> 99% ee).
Diastereoselectividades altas (hasta 20:1 d.r.) se han observado.
Los productos se elaboraron eficientemente en compuestos cíclicos y acíclicos complejos con hasta cuatro estereocentros.

Conclusiones:

La sustitución alilica asimétrica bifásica catalizada por iridio es un método versátil y eficiente.
Proporciona un acceso rápido a bloques de construcción quirales valiosos a partir de precursores simples.
La metodología facilita la síntesis de moléculas complejas con múltiples estereocentros.

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