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Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides
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Alquilación nucleofílica regioselectiva / arilación de enlaces B-H en o-carboranos: un método alternativo para la
Cen Tang1, Jiji Zhang1, Jie Zhang1
1Department of Chemistry and State Key Laboratory of Synthetic Chemistry , The Chinese University of Hong Kong , Shatin , New Territories, Hong Kong , China.
Journal of the American Chemical Society
|November 17, 2018
Resumen
Un nuevo método mediado por magnesio permite la sustitución nucleofílica regioselectiva de enlaces B-H en o-carboranos. Este enfoque ofrece una estrategia complementaria para sintetizar o-carboranos alquilados y arilados selectivamente.
Área de la Ciencia:
- Química organometálica
- Química del boro
- Síntesis orgánica
Sus antecedentes:
- Los o-carboranos son grupos de boro versátiles con propiedades electrónicas únicas.
- Los métodos existentes para la funcionalización de los o-carboranos incluyen la catálisis de metales de transición y la sustitución electrofílica.
- El desarrollo de protocolos de sustitución nucleófila regioselectiva es crucial para expandir su utilidad sintética.
Objetivo del estudio:
- Introducir un nuevo protocolo para la sustitución regioselectiva de la jaula nucleofílica B-H en los o-carboranos.
- Complementar las estrategias existentes de catálisis de metales de transición y sustitución electrofílica.
- Para sintetizar los nuevos o-carboranos B3,6-dialquilados y B9,-alquilados/arilados.
Principales métodos:
- Se emplearon reacciones mediadas por magnesio para la sustitución nucleofílica selectiva del sitio.
- Las reacciones se dirigieron a las posiciones B ((3,6) -H y B ((9) -H de los o-carboranos.
- Se analizaron los factores estéricos y electrónicos de los sustituyentes de la jaula C para determinar su papel en la selectividad.
Principales resultados:
- Se desarrolló con éxito un nuevo protocolo para la sustitución regioselectiva de la jaula nucleofílica B-H.
- Se obtuvieron elevados rendimientos de o-carboranos B3,6-dialquilados y B9,-alquilados/arilados.
- Se encontró que la selectividad del sitio estaba significativamente influenciada por los factores estéricos y electrónicos de los sustituyentes C.
Conclusiones:
- El método propuesto mediado por magnesio proporciona un enfoque potente y complementario para la funcionalización de o-carborano.
- Este protocolo permite la síntesis eficiente de o-carboranos específicamente sustituidos.
- Comprender el papel de los sustituyentes C es clave para controlar la regioselectividad en las reacciones de sustitución nucleófila.
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