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Manosilación estereoselectiva utilizando las 2,6-lactonas
Yusuke Hashimoto1, Saki Tanikawa1, Ryota Saito1
1Department of Chemistry, Toho University , 2-2-1 Miyama, Funabashi 274-8510 Japan.
Journal of the American Chemical Society
|October 27, 2016
Resumen
Una nueva estrategia de 2,6-lactona permite la β-manosilación estereoselectiva, superando la formación típica de α-glucósidos. Este método utiliza tricloroacetimidatos de glucosilo y un sistema de catalizador único para una síntesis eficiente de β-manósidos.
Área de la Ciencia:
- Química de los carbohidratos
- Síntesis orgánica
- Reacciones estereoselectivas
Sus antecedentes:
- Las reacciones de glicosilación generalmente favorecen la formación de α-glucósidos debido a los efectos estereoelectrónicos que favorecen los mecanismos SN1.
- El logro de la estereoselectividad β en la mannosilación es un desafío, pero crucial para la síntesis de glucoconjugados biológicamente relevantes.
Objetivo del estudio:
- Desarrollar una nueva estrategia para la β-manosilación estereoselectiva.
- Investigar la utilidad de las fracciones de 2,6-lactona en el control de la estereoquímica de la glicosilación.
Principales métodos:
- Se utilizaron tricloroacetimidatos de glicosilo como donantes con una fracción de 2,6-lactona.
- Se utiliza un sistema de catalizador combinado de AuCl3 y 3,5-bis (trifluorometil) feniltiourea.
- Se investigó el efecto de la concentración de reacción en la estereoselectividad del producto.
Principales resultados:
- La fracción de 2,6-lactona suprimió efectivamente la vía SN1 competidora, promoviendo la formación de β-glucósidos a través de mecanismos similares a los de SN2.
- Se logró una alta estereoselectividad β, con un resultado esterequímico influenciado por la concentración de reacción.
- Incluso bajo condiciones SN1, el catión glicosilo exhibió una influencia estérica de dirección β.
Conclusiones:
- La estrategia de la 2,6-lactona es muy eficaz para lograr la mannosilación estereoselectiva β.
- Este enfoque ofrece una herramienta valiosa para la síntesis de β-manósidos complejos.
- Los hallazgos proporcionan información sobre el control de la estereoquímica en las reacciones de glicosilación.
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