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Rodio catiónico ((I) complejo catalizado [3 + 2] y [2 + 1] cicloadiciones de ésteres de propargilo con alquinos y
Yu Shibata1, Keiichi Noguchi, Ken Tanaka
1Department of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
Journal of the American Chemical Society
|May 22, 2010
Resumen
Un complejo catiónico de rodio ((I) cataliza eficientemente dos reacciones distintas de cicloadición. Promueve [3+2] cicloadiciones de ésteres de propargilo y [2+1] ciclopropanaciones con alto rendimiento y selectividad.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Síntesis orgánica La síntesis orgánica.
Sus antecedentes:
- Los complejos de rodio (I) son catalizadores versátiles en las transformaciones orgánicas.
- Las reacciones de cicloadición son cruciales para la construcción de moléculas orgánicas cíclicas.
- Los ésteres de propargilo son valiosos bloques de construcción sintéticos.
Objetivo del estudio:
- Para investigar la actividad catalítica de un complejo catiónico de rodio ((I), [Rh ((cod) ((2)) ]SbF ((6).
- Para explorar su aplicación en reacciones de [3+2] cicloadición.
- Para examinar su utilidad en las reacciones de [2+1] ciclopropanación.
Principales métodos:
- Empleando un complejo catiónico de rodio (I), (Rh (cod) (2)) y (SbF (6), como catalizador.
- Reaccionando los ésteres de propargilo con los carboxilatos de dialquilo acetilenedicarboxilato para la [3+2] cicloadición.
- Reaccionando los ésteres de propargilo con las acrilamidas N,N-disubstituidas para la [2+1] ciclopropanación.
Principales resultados:
- El complejo de rodio (I) catalizó efectivamente la [3+2] cicloadición de ésteres de propargilo con dialquilo acetilenedicarboxilatos, produciendo los productos con buenos rendimientos.
- El mismo catalizador facilitó la [2+1] cicloadición (ciclopropanación) de ésteres de propargilo con acrilamidas N,N-disubstituidas.
- La reacción de ciclopropanación procedió con una perfecta diastereoselectividad.
Conclusiones:
- El complejo catiónico de rodio (I) es un potente catalizador tanto para las reacciones de [3+2] como para las de [2+1] cicloadición.
- El mecanismo catalítico para la cicloadición [3+2] probablemente involucra a los intermediarios de cationic rhodium (I) alkenylcarbene estabilizados con carbonyl.
- Este estudio destaca una nueva ruta sintética para la construcción de moléculas orgánicas complejas con alta eficiencia y selectividad.
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