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Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions
Published on: March 20, 2014
Generación, reacciones y cinética de los difenilicarbeno triplet estéricamente congestionados. Efectos de los grupos
Hideo Tomioka1, Tetsuya Watanabe, Makoto Hattori
1Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan.
Journal of the American Chemical Society
|January 17, 2002
Resumen
Los difenilcarbenos polibromados (DPC) exhiben una mayor estabilidad, con algunos DPC triplet que duran hasta 16 segundos. Los efectos de los sustituyentes, en particular los grupos tert-butilo, influyen significativamente en su reactividad y vida útil.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La fotoquímica es la fotoquímica.
- Química de los carbenos La química de los carbenos
Sus antecedentes:
- Los difenilcarbenos polibromados (DPC, por sus siglas en inglés) son intermediarios reactivos.
- Comprender la estabilidad de los carbenos es crucial para las aplicaciones sintéticas.
Objetivo del estudio:
- Para sintetizar y caracterizar los nuevos difenilicarbeno polibromados (DPC).
- Para investigar la reactividad y la estabilidad de los DPC triplet.
- Para explorar la influencia de los para-sustitutos en el tiempo de vida del carbeno.
Principales métodos:
- Generación de DPC a través de la irradiación de los precursores diazometanos.
- Espectroscopias de baja temperatura para la caracterización.
- Fotólisis de flash láser para estudios de reactividad.
Principales resultados:
- El triplete bis ((2,4,6-tribromofenil) carbeno tiene una vida media de 1 segundo en el benceno.
- Los para-sustitutos muestran efectos anómalos: los grupos metilo disminuyen la vida útil, los grupos tert-butilo la aumentan.
- El triplete bis ((2,6-dibromo-4-tert-butilfenil) carbeno exhibe una vida media de 16 segundos.
Conclusiones:
- Los difenilcarbenos polibromados (DPC) pueden ser estabilizados de manera significativa por sustituyentes específicos.
- Los grupos tert-butilo en la posición para mejoran dramáticamente la estabilidad de los carbenos triplet.
- Se exploraron otras estrategias como el apuntalamiento y los efectos sinérgicos para aumentar la estabilidad del DPC.
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