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Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols

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Hidroboración asimétrica catalizada por cobalto y ciclización de 1,6-Enynes con pinacolborano

Songjie Yu¹, Caizhi Wu¹, Shaozhong Ge¹

¹Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.

Journal of the American Chemical Society

|April 29, 2017

Resumen

Este estudio introduce un nuevo método catalizado por cobalto para la hidroboración/ciclización asimétrica de 1,6-eninas. La reacción produce eficientemente ésteres de boronato quirales valiosos con alta enantioselectividad.

Área de la Ciencia:

Química orgánica
Catálisis
Síntesis asimétrica

Sus antecedentes:

Las 1,6-eninas son sustratos versátiles para las reacciones de ciclización.
La hidroboración asimétrica es un método clave para introducir la quiralidad y la funcionalización del boro.

Objetivo del estudio:

Desarrollar una nueva hidroboración/ciclización asimétrica catalizada por cobalto de 1,6-eninas.
Para sintetizar el tetrahidrofurano quiral, el ciclopentano y las fracciones de pirrolidina.

Principales métodos:

Se utilizan catalizadores generados a partir de Co ((acac) 2) y ligandos quirales de bisfosfina.
Activación in situ con pinacolborano (HBpin).
Aplicado a varias 1,6-eniinas atadas al oxígeno, nitrógeno y carbono.

Principales resultados:

Se obtienen enantioselectividades de altas a excelentes (86%-99% ee).
Se han sintetizado con éxito ésteres de boronato sustituidos por alquilo y vinilo.
Demostró la amplia aplicabilidad del sistema catalítico.

Conclusiones:

El sistema catalizado por cobalto desarrollado es eficaz para la hidroboración/ciclización asimétrica de 1,6-eninos.
Este método proporciona acceso a bloques de construcción quirales valiosos con un alto control estéreo.

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