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Reducción de las enaminas ricas en electrones por transferencia de electrones acoplados a protones
Scott S Kolmar1, James M Mayer1
1Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States.
Journal of the American Chemical Society
|July 19, 2017
Resumen
El dióxido de samario (SmI2) con agua actúa como un potente reductor, reduciendo eficientemente las enaminas a través de una vía concertada de transferencia de electrones acoplados a protones. Esto indica que SmI2 ((H2O) n es un donante de átomos de hidrógeno fuerte, capaz de formar enlaces C-H muy débiles.
Área de la Ciencia:
- Química orgánica
- Química de las redox
- Desarrollo de reactivos
Sus antecedentes:
- El dioduro de samario (SmI2) es un agente reductor versátil, utilizado principalmente para compuestos carbonílicos.
- Estudios recientes destacan el SmI2 en presencia de agua y el THF (SmI2 ((H2O) n) como un reactivo útil.
- Las enaminas son sustratos ricos en electrones que presentan desafíos de reducción únicos.
Objetivo del estudio:
- Para investigar la reducción de las enaminas utilizando SmI2(H2O) n.
- Para dilucidar el mecanismo de reacción, diferenciando entre varias vías de transferencia de electrones y protones.
- Para evaluar la capacidad de donación de átomos de hidrógeno de SmI2(H2O) n.
Principales métodos:
- Reducción experimental de las enaminas utilizando SmI2(H2O) n.
- Estudios mecánicos que incluyan pruebas contra la transferencia inicial de electrones a la esfera externa, la transferencia de protones o la coordinación del sustrato.
- Análisis termoquímico para determinar las energías libres de disociación de enlaces (BDFEs).
Principales resultados:
- SmI2 ((H2O) n reduce efectivamente las enaminas.
- Los experimentos mecánicos apoyan fuertemente una vía concertada de transferencia de electrones acoplados a protones (PCET).
- El enlace C-H formado tiene un BDFE de ~ 32 kcal mol-1, y el O-H BDFE del ion acuario es de ~ 26 kcal mol-1.
- Estos valores indican que SmI2 ((H2O) n es un donante de átomos de hidrógeno muy fuerte.
Conclusiones:
- SmI2 ((H2O) n es un potente agente reductor para sustratos ricos en electrones como las enaminas.
- La reducción procede a través de un mecanismo PCET, no una simple transferencia de electrones o transferencia de protones en la esfera externa.
- La capacidad del reactivo para formar enlaces C-H muy débiles subraya su fuerza como donante de átomos de hidrógeno.
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