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Formación de enlaces carbono-nitrógeno utilizando hexametildisilazida de sodio: reactividades y mecanismos
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States.
Journal of the American Chemical Society
|October 19, 2023
Resumen
La reactividad del hexametildisilazido de sodio (NaHMDS) con los electrófilos es dependiente del disolvente. Este estudio revela nuevas reacciones y conocimientos mecanicistas sobre la química de NaHMDS, que afectan a la síntesis orgánica.
Área de la Ciencia:
- Química orgánica
- Química sintética
- Mecanismos de reacción
Sus antecedentes:
- El hexametildisilazido de sodio (NaHMDS) es una base ampliamente utilizada en la síntesis orgánica.
- Comprender su reactividad con varios electrófilos es crucial para desarrollar nuevas metodologías sintéticas.
Objetivo del estudio:
- Investigar la reactividad dependiente del disolvente del NaHMDS con electrófilos centrados en el carbono.
- Descubrir y caracterizar nuevas reacciones relacionadas con el NaHMDS.
- Para aclarar la base mecanicista de los patrones de reactividad observados.
Principales métodos:
- Estudios experimentales que incluyen reacciones de NaHMDS con ésteres metílicos aromáticos, haluros de arilo y epóxidos.
- Análisis espectroscópico que incluye RMN de 1H y 29Si utilizando NaHMDS etiquetado isotópicamente ([15N]NaHMDS).
- Estudios cinéticos y modelado computacional para comprender los mecanismos de reacción.
Principales resultados:
- Aminólisis directa de ésteres metílicos aromáticos para formar carboxamidas, nitriles o amidinas, que dependen en gran medida del disolvente.
- SNAr sustituciones exitosas de haluros de arilo y la apertura de los epóxidos terminales.
- Identificación de las preferencias específicas de los disolventes para la formación de productos, con el tolueno y la dimetiletilamina favoreciendo las carboxamidas, y el THF favoreciendo los nitriles o las amidinas.
- Observación de especies de dimeros y de dimeros mixtos significativos de NaHMDS en el THF, incluso cuando se parte del monómero.
Conclusiones:
- La reactividad del NaHMDS está significativamente influenciada por el disolvente, lo que permite diversas transformaciones.
- Las vías mecanicistas complejas, incluidas las vías involucradas con dimeros, dictan el resultado de las reacciones NaHMDS.
- Este trabajo amplía la utilidad sintética conocida de NaHMDS y proporciona una comprensión mecánica más profunda.
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