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Synthesis and Characterization of Functionalized Metal-organic Frameworks
Published on: September 5, 2014
Intercambio dinámico de ligandos del complejo lantánido que conduce a la transformación estructural y funcional:
Shin-ya Tosaki1, Riichiro Tsuji, Takashi Ohshima
1Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Journal of the American Chemical Society
|February 17, 2005
Resumen
Este estudio introduce un complejo de samario para la epoxidación asimétrica catalítica y la posterior apertura del epoxido. El proceso secuencial produce eficientemente productos valiosos de azido-hidroxiamida con alta selectividad y rendimiento.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis de la catálisis.
- Química de los Lantánidos
Sus antecedentes:
- Los complejos de lantánidos ofrecen capacidades dinámicas de intercambio de ligandos para la alteración funcional in situ.
- La epoxidación asimétrica y las transformaciones subsiguientes son cruciales en la química sintética.
Objetivo del estudio:
- Desarrollar un proceso catalítico secuencial para la epoxidación asimétrica y la apertura de epóxido regioselectivo.
- Investigar el papel del intercambio dinámico de ligandos en la generación de reactivos intermedios.
Principales métodos:
- Epoxidación asimétrica catalítica de amidas alfa, beta insaturadas mediante el uso de un complejo Sm-(S) -BINOL-Ph3As=O.
- Generación in situ de un complejo de azido de samario a través del intercambio dinámico de ligandos.
- Apertura de epoxida mediante el uso de azido de trimetilsililo (Me3SiN3).
Principales resultados:
- Excelentes rendimientos totales (hasta el 99%) y exceso enantiomérico (hasta >99%) para los productos anti-beta-azido-alfa-hidroxiamida.
- Regioselectividad completa en el paso de apertura del epoxido.
- Evidencia para la generación de complejos de azida de samario in situ a través de la espectroscopia IR.
Conclusiones:
- El intercambio dinámico de ligandos de los complejos lantánidos permite procesos catalíticos secuenciales eficientes.
- El complejo de azida de samario es un intermediario altamente reactivo para la apertura de epoxidas.
- La basicidad de Lewis de la fracción de amida mejora la reactividad tanto en la epoxidación como en las reacciones de apertura.
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