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Published on: October 19, 2017
Apertura de acetalos de tartrato utilizando bromuro de dialquilborón: evidencia de estereoselectividad aguas abajo de
Yvan Guindon1, William W Ogilvie, Josée Bordeleau
1Boehringer Ingelheim (Canada) Ltd., Bio-Méga Research Division, 2100 rue Cunard, Laval Québec, Canada H7S 2G5.
Journal of the American Chemical Society
|January 9, 2003
Resumen
Este estudio introduce un nuevo método utilizando acetalos de tipo Johnson para sintetizar alcoholes secundarios con alta diastereoselectividad. El proceso implica la participación del ácido de Lewis y las transformaciones estereospecíficas para una síntesis eficiente.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Síntesis asimétrica de síntesis.
Sus antecedentes:
- Los auxiliares quirales son cruciales para la síntesis estereoselectiva.
- El tartrato de dimetilo es un versátil material de partida para piscinas quirales.
Objetivo del estudio:
- Desarrollar una nueva síntesis diastereoselectiva de alcoholes secundarios.
- Para dilucidar el mecanismo de la inducción de la estereoselectividad.
Principales métodos:
- Preparación de acetalos de tipo Johnson a partir de aldehídos y tartrato de dimetilo.
- Apertura del anillo con bromuro de dimetilborón (Me2BBr) seguido de desplazamiento de cuprato.
- Análisis estereoquímico de los alcoholes secundarios resultantes.
Principales resultados:
- Se logra una alta diastereoselectividad (>30:1) en la síntesis secundaria de alcohol.
- Propuso un mecanismo que involucra la participación del ácido de Lewis y la transformación estereospecífica del bromo acetal.
- Se ha demostrado la eliminación auxiliar mediante reducción de SmI2 o tratamiento con metóxido.
Conclusiones:
- El método desarrollado ofrece una ruta altamente diastereoselectiva a los alcoholes secundarios.
- El mecanismo destaca el papel del ácido de Lewis y la estereospecificidad dependiente de la temperatura.
- Este enfoque proporciona una herramienta valiosa para la síntesis asimétrica.
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