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Enantioselectivas organocatalíticas y térmicas [4 + 4] Cicloadiciones

Vasco Corti¹, Casper Larsen Barløse¹, Niklas Lawaetz Østergaard¹

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

Journal of the American Chemical Society

|January 5, 2023

Resumen

Este estudio introduce la primera asimetría organocatalítica [4 + 4] de cicloadición para la construcción de carbociclos quirales de ocho miembros. El nuevo método proporciona un acceso eficiente a valiosos derivados de ciclo-octadieno con alto estereocontrol.

Área de la Ciencia:

Química orgánica
Catálisis
Síntesis estereoselectiva

Sus antecedentes:

Los carbociclos quirales de ocho miembros son cruciales en la química de medicamentos y productos naturales.
Los métodos sintéticos existentes para estas estructuras son limitados, lo que dificulta el diseño racional y la síntesis estereoselectiva.

Objetivo del estudio:

Desarrollar la primera asimetría organocatalítica [4 + 4] de la cicloadición para la síntesis quiral de carbociclos de ocho miembros.
Establecer una vía sencilla y económica para los derivados de ciclo-octadieno.

Principales métodos:

La adición organocatalítica asimétrica [4 + 4] de 9H-fluoreno-1-carbaldehído con dienos deficientes en electrones.
Se utilizó la aminocatálisis para formar un componente de butadieno polarizado.
Se empleó la teoría funcional de la densidad (DFT) y el análisis de la órbita molecular de frontera (FMO) para dilucidar el mecanismo de reacción.

Principales resultados:

Se obtienen buenos rendimientos de derivados de ciclooctadieno con una excelente peri-, diastereo- y enantioselectividad.
Demostró la formación de ciclooctadienos funcionalizados y su elaboración sintética en diversos andamios quirales.
El análisis de la FMO indicó características HOMO y LUMO similares al butadieno.

Conclusiones:

La metodología desarrollada ofrece una nueva herramienta poderosa para acceder a carbociclos quirales complejos.
La reacción procede a través de un mecanismo único que involucra cicloadiciones reversibles [4 + 2] y retro [4 + 2] antes de la clave [4 + 4].
Este enfoque organocatalítico permite la construcción de valiosos derivados de ciclo-octadieno con un alto control estereoquímico.

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