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Racionalización mecánica de la adición de conjugados organocatalizados de aldehídos lineales a las nitroolefinas

Jordi Burés¹, Alan Armstrong, Donna G Blackmond

¹Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA.

Journal of the American Chemical Society

|May 17, 2011

Resumen

Los catalizadores de éter de diarilprolinol facilitan la adición de conjugado de propanal y nitrostireno. La comprensión de la formación de iones de iminio que determina la velocidad y el intermedio estereoselectivo ciclobutano optimiza los protocolos de reacción para una alta productividad.

Área de la Ciencia:

Química orgánica es la química orgánica.
La cinética de la reacción.
La catálisis es la catálisis.

Sus antecedentes:

Las reacciones de adición conjugada son fundamentales en la síntesis orgánica.
Los éteres de diarilprolinol son organocatalizadores efectivos. también conocidos como diarilprolinol.
La comprensión de los mecanismos de reacción es crucial para la optimización.

Objetivo del estudio:

Para investigar la cinética de la adición de conjugado propanal al nitrostireno catalizado por éteres de diarilprolinol.
Para aclarar el paso que determina la velocidad y los factores que influyen en la estereoselectividad.
Desarrollar protocolos de reacción optimizados basados en conocimientos mecanicistas.

Principales métodos:

Estudios cinéticos mediante el uso de métodos espectroscópicos.
Análisis de los efectos de los productos de reacción y de los aditivos ácidos.
Análisis estereoquímico para determinar el exceso enantiomérico.

Principales resultados:

La formación de especies de iminium se identificó como el paso que determina la velocidad.
Se encontró que el producto de reacción y los aditivos ácidos promueven la formación de iminio.
Un intermediario de ciclobutano fue crucial para una alta estereoselectividad.

Conclusiones:

Se logró una comprensión mecánica de la reacción de adición conjugada.
Los protocolos optimizados que utilizan catalizadores de éter de diarilprolinol conducen a resultados altamente productivos.
El estudio destaca la importancia de las estructuras intermedias en el control de la estereoselectividad.

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