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Mecanismos de la sin-inserción de alquinas y alenos en enlaces oro-silicio: un estudio experimental/teórico
Maximilian Joost1, Laura Estevez, Sonia Mallet-Ladeira
1Université de Toulouse, UPS, Laboratoire Hétérochimie Fondamentale Appliquée, 118 route de Narbonne, F-31062 Toulouse, France.
Journal of the American Chemical Society
|July 8, 2014
Resumen
Este estudio revela el mecanismo de la inserción de alquino y aleno catalizados por oro en enlaces oro-silicio. La reacción procede a través de una vía de esfera interna de dos pasos, confirmada por la cinética y los cálculos de DFT.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Mecanismos de reacción Mecanismos de reacción
Sus antecedentes:
- Los complejos oro-silicio son versátiles intermedios en la síntesis orgánica.
- Comprender el mecanismo de inserción de alquinos y alenos es crucial para el diseño de catalizadores.
Objetivo del estudio:
- Para aclarar el mecanismo detallado de la sin-inserción de alquinos y alenos en los enlaces Au-Si.
- Para investigar el papel de los complejos silyl de oro en estas transformaciones.
- Racionalizar la selectividad regional observada, en particular para todos en general.
Principales métodos:
- Se realizaron experimentos cinéticos para determinar los órdenes de reacción y los parámetros termodinámicos.
- Se emplearon cálculos de la Teoría Funcional de Densidad (DFT) para explorar vías mecanicistas.
- Los estudios computacionales incluyeron correcciones de dispersión (funcional B97D) para una estimación precisa de la entalpía de activación.
Principales resultados:
- La reacción es de primer orden tanto en el complejo silílico alquino como en el complejo silílico dorado, lo que indica un mecanismo de asociación bimolecular.
- Se propuso un mecanismo de esfera interna en dos etapas: coordinación de alquinos seguido de la inserción migratoria que determina la velocidad.
- La entalpía teórica de activación (11,5 kcal·mol−1) coincidía estrechamente con los valores experimentales (13,7 kcal·mol−1).
- La regioselectividad fue racionalizada, con una inusual inserción de aleno explicada por una inserción de doble enlace terminal y posterior isomerización Au/Si.
Conclusiones:
- El estudio proporciona pruebas sólidas de un mecanismo de coordinación e inserción en los centros de oro.
- Se apoyan los mecanismos de la esfera interna para la funcionalización de alquinos y alenos con complejos silílicos dorados.
- Los hallazgos contribuyen a una comprensión más profunda de las reacciones catalizadas por oro que involucran sustratos de silicio.
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