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Adición asistida por aire de reactivos de grignard a las olefinas. Un protocolo simple para un proceso de
Youhei Nobe1, Kyohei Arayama, Hirokazu Urabe
1Department of Biomolecular Engineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B-59 Nagatsuta-cho, Yokohama, Kanagawa 226-8501, Japan.
Journal of the American Chemical Society
|December 22, 2005
Resumen
Los reactivos de Grignard reaccionan con las olefinas en el aire para formar alcoholes homologados. Esta reacción mediada por el aire probablemente involucra un mecanismo radical, ofreciendo una nueva ruta sintética.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Química organometálica Química orgánica de los metales.
Sus antecedentes:
- Los reactivos de Grignard son compuestos organometálicos versátiles ampliamente utilizados en la síntesis orgánica.
- Las adiciones tradicionales de Grignard a las olefinas generalmente se realizan bajo atmósferas inertes para evitar reacciones secundarias.
Objetivo del estudio:
- Para investigar la adición intermolecular de varios reactivos de Grignard a las olefinas bajo una atmósfera de aire.
- Explorar una nueva vía sintética para la formación de alcoholes homologados.
Principales métodos:
- Reacción de los reactivos sililmetilo, terciario-alquilo, alquenilo y arilo de Grignard con las olefinas (estirenos, dienos conjugados, eninas) bajo una atmósfera de aire.
- Estudio comparativo con reacciones realizadas bajo una atmósfera inerte (argon) para dilucidar el mecanismo de reacción.
Principales resultados:
- Síntesis exitosa de alcoholes homologados a partir de reactivos de Grignard y olefinas en presencia de aire.
- Demostración de que la reacción no procede bajo la estricta exclusión del oxígeno, lo que sugiere una vía radical.
- Se ha logrado de buena a excelente diastereoselecto- o regioselectividad en ejemplos representativos.
Conclusiones:
- La adición intermolecular de reactivos de Grignard a las olefinas puede ser efectivamente mediada por el aire.
- Es probable que la reacción proceda a través de un mecanismo radical iniciado por la oxidación aérea del reactivo de Grignard.
- Este método proporciona una nueva ruta a los alcoholes funcionalizados con alta selectividad.
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