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Reacciones de petasis asimétricas catalizadas por los bifenolos quirales
1Department of Chemistry, Center for Chemical Methodology and Library Development, Boston University, 24 Cummington Street, Boston, Massachusetts 02215, USA.
Journal of the American Chemical Society
|May 8, 2008
Resumen
Los bifenolos quirales, como el (S) -VAPOL, catalizan efectivamente la reacción de Petasis, produciendo valiosos ésteres alfa-amino quirales. Esta síntesis enantioselectiva ofrece altos rendimientos de producto y un excelente control estereoquímico.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Catalización asimétrica por catálisis asimétrica.
Sus antecedentes:
- La reacción de Petasis es una reacción multicomponente que involucra ácidos borónicos, aminas y aldehídos.
- El desarrollo de métodos enantioselectivos para esta reacción es crucial para la síntesis de moléculas quirales.
Objetivo del estudio:
- Investigar el uso de bifenolos quirales como catalizadores para la reacción enantioselectiva de Petasis.
- Explorar el mecanismo de reacción y optimizar las condiciones para el alto rendimiento y la enantioselectividad.
Principales métodos:
- Utilizando (S) -VAPOL (un bifenol quiral) como catalizador (15 mol por ciento).
- Utilizando alquenil boronatos, aminas secundarias y glioxilato de etilo como reactivos.
- El uso de 3 Å tamices moleculares como un aditivo.
Principales resultados:
- Se obtienen buenos a excelentes rendimientos (71-92%) de los productos de éster alfa-amino quiral.
- Se obtienen altas relaciones enantioméricas, que van desde 89:11 a 98:2.
- Los estudios mecánicos sugirieron el intercambio de un solo ligando y los intermediarios de boronato tetracoordinado.
Conclusiones:
- Los bifenolos quirales son catalizadores efectivos para la reacción enantioselectiva de Petasis.
- El método desarrollado proporciona una ruta confiable para sintetizar ésteres alfa-amino quirales con alta pureza estereoquímica.
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