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Reducción diastereo-selectiva controlada por quelación de las alfa-fluorocetonas
Pramod K Mohanta1, Todd A Davis, Jeremy R Gooch
1Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
Journal of the American Chemical Society
|August 25, 2005
Resumen
El tetracloruro de titanio (TiCl4) permite la reducción diastereoselectiva de las alfa-fluorocetonas a los alcoholes sin-alfa-fluoro a través del control de quelación. Otros ácidos de Lewis de titanio promueven la formación de anti-diastereómeros a través de vías de no quelación.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Síntesis estereoselectiva de síntesis.
Sus antecedentes:
- El control de la diastereoselectividad en la reducción de las alfa-fluorocetonas es crucial para la síntesis de alcoholes quirales de alfa-fluoro.
- Los ácidos de Lewis a base de titanio se exploran por su potencial para influir en las vías de reacción.
Objetivo del estudio:
- Investigar el uso de ácidos de Lewis basados en Ti para la reducción diastereoselectiva de la alfa-fluoropropiofenona.
- Para determinar si el control de quelación puede dirigir el resultado estereocímico de la reducción.
Principales métodos:
- Tratamiento de la alfa-fluoropropiofenona con TiCl4 o Ti(OiPr) 4 seguido de la reducción de LiBH4.
- Análisis de los productos de reacción utilizando espectroscopia de RMN 1H, 13C y 19F.
Principales resultados:
- El pretratamiento de TiCl4 produjo predominantemente el diastereómero de síntesis, lo que indica un control de quelación.
- El pretratamiento de Ti ((OiPr) 4 produjo predominantemente el antidiastéreo, lo que sugiere una vía de no quelación.
- Los estudios de RMN confirmaron la quelación entre TiCl4 y el sustrato.
Conclusiones:
- El control de la quelación utilizando TiCl4 es una estrategia eficaz para la síntesis diastereoselectiva de los alcoholes sin-alfa-fluoro.
- El enfoque es general para otras alfa-fluorocetonas, lo que demuestra una amplia aplicabilidad.
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