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Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
Construcción alquilativa controlada estereológicamente de centros de carbono cuaternario
David A Kummer1, William J Chain, Marvin R Morales
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Journal of the American Chemical Society
|September 16, 2008
Resumen
Este estudio presenta métodos eficientes y diastereoselectivos para crear enolados alfa, alfa-disubstituidos utilizando amidas de pseudoefedrina. Estos enolados se someten a una alquilación estereospecífica, lo que produce valiosos bloques de construcción quirales para la síntesis.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La síntesis estereoselectiva de síntesis.
Sus antecedentes:
- El desarrollo de métodos para la formación estereodefinida de enolados alfa, alfa-disubstituidos es crucial para la síntesis asimétrica.
- Las amidas de pseudoefedrina sirven como auxiliares quirales efectivos en el control de la estereoquímica.
Objetivo del estudio:
- Establecer protocolos para la generación estereodefinida de enolados alfa, alfa-disubstituidos de amidas de pseudoefedrina.
- Para implementar estos enolados en reacciones de alquilación diastereoselectiva para crear moléculas complejas.
Principales métodos:
- Deprotonación directa y alquilación de sustratos de amida de pseudoefedrina.
- Caminos de enolización y alquilación estereospecíficos.
- Adición conjugada de reactivos de alquillitio a las amidas de pseudoefedrina insaturadas.
Principales resultados:
- Se logró una alquilación directa eficiente y diastereoselectiva de las amidas de pseudoefedrina alfa, alfa-disubstituidas.
- Se observó la sustitución estereospecífica del enlace alfa-C-H por un grupo alfa-C-alquilo con la retención de la estereoquímica.
- Se demostró la generación de enolato estereocontrolada alternativa a través de la adición conjugada.
Conclusiones:
- Los métodos desarrollados proporcionan acceso a las amidas de pseudoefedrina alfa, alfa-disubstituidas con alto estereocontrol.
- Estos productos pueden transformarse fácilmente en varios compuestos ópticamente activos, incluidos los ácidos carboxílicos, cetonas, alcoholes y aldehídos.
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