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Estereocontrol inducido por la coordinación sobre los carbocationes: desoxigenación reductora asimétrica de los
Mayuko Isomura1, David A Petrone1, Erick M Carreira1
1ETH Zürich , Vladimir-Prelog-Weg 3 , HCI, 8093 Zürich , Switzerland.
Journal of the American Chemical Society
|February 21, 2019
Resumen
Los investigadores desarrollaron una nueva estrategia de acoplamiento para la catálisis asimétrica, lo que permite reacciones estereoselectivas en carbocationes terciarios. Este método logra la primera desoxigenación reductora enantioselectiva de alcoholes terciarios con alta selectividad.
Área de la Ciencia:
- Química orgánica
- Catálisis
- Síntesis asimétrica
Sus antecedentes:
- Los carbocationes terciarios son difíciles de controlar estereoselectivamente en la catálisis.
- Esta limitación ha restringido su uso como intermediarios en la síntesis asimétrica.
Objetivo del estudio:
- Desarrollar un método para el ataque nucleofílico estereoselectivo a los carbocationes terciarios.
- Lograr la primera desoxigenación reductora enantioselectiva de los alcoholes terciarios.
Principales métodos:
- Una estrategia de acoplamiento que utiliza la coordinación reversible del sustrato con un catalizador quiral de metales de transición.
- Utilizó un nuevo análogo de éster de Hantzsch como fuente de hidruro.
- Se emplearon estudios mecanicistas en profundidad.
Principales resultados:
- Se ha logrado un ataque nucleófilo altamente estereoselectivo a los carbocationes terciarios.
- Se ha demostrado la primera desoxigenación reductora enantioselectiva de alcoholes terciarios con un exceso enantiomérico de hasta el 96% (ee).
- Se obtiene una alta regioselectividad (hasta >50:1 rr).
Conclusiones:
- La estrategia de acoplamiento permite un control estéreoquímico preciso de los intermediarios de carbocatión.
- Este avance abre nuevas vías para la catálisis asimétrica que involucra carbocationes terciarios.
- El método desarrollado proporciona una ruta robusta para la desoxigenación enantioselectiva de los alcoholes terciarios.
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