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Construcción enantioselectiva organocatalizadora de atropisómeros conformacionalmente estables

Giulio Bertuzzi¹, Vasco Corti¹, Joseph A Izzo¹

¹Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.

Journal of the American Chemical Society

|January 6, 2022

Resumen

Los investigadores desarrollaron un nuevo método para sintetizar atropisómeros quirales C ((sp2) - C ((sp3)), que son moléculas con un eje estereogénico estable. Este enfoque organocatalítico logra una alta estereoselectividad y ofrece un protocolo general para crear estos compuestos complejos.

Área de la Ciencia:

Química orgánica
Estereoquímica
Síntesis asimétrica

Sus antecedentes:

Los atropisómeros no-biarilo poseen un eje estereogénico con al menos un grupo no-areno.
Los ejes estereogénicos C ((sp2) - C ((sp3) conformalmente estables se encuentran en productos naturales, pero su síntesis está poco explorada.

Objetivo del estudio:

Desarrollar una síntesis enantioselectiva para una nueva clase de atropisómeros quirales C ((sp2) -C ((sp3).
Establecer un protocolo amplio y general para crear estos compuestos con diversos motivos moleculares.

Principales métodos:

Se empleó la metodología organocatalítica asimétrica.
Se utilizaron cálculos de la teoría funcional de la densidad (DFT).
Se realizaron investigaciones experimentales para analizar la estabilidad conformacional y los mecanismos de reacción.

Principales resultados:

Se sintetizó una nueva clase de atropisómeros quirales C ((sp2) - C ((sp3)) con alta estereoselectividad (hasta el 99% ee).
El eje estereogénico C ((sp2) - C ((sp3)) demostró una notable estabilidad conformacional (t1/2 > 1000 años a 25°C).
Se observó un control cinético sobre el elemento estereogénico, con evidencia que apoya un escenario de Curtin-Hammett.

Conclusiones:

El método organocatalítico desarrollado proporciona una vía general y altamente estereoselectiva para los nuevos atropisómeros C ((sp2) -C ((sp3).
El estudio proporciona información sobre la estabilidad conformacional y el control cinético que rigen este raro elemento estereogénico.
Se obtuvieron pruebas de conversiones de quiralidad central a axial, avanzando en la comprensión de las transformaciones estereoquímicas.

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