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Preorganización en una reacción de reordenamiento de diaza-Cope altamente enantioselectiva

Hae-Jo Kim¹, Hyunwoo Kim, Gamil Alhakimi

¹Department of Chemistry, University of Toronto, 80 St. George Street, Toronto M5S 3H6, Canada.

Journal of the American Chemical Society

|November 25, 2005

Resumen

El reordenamiento de Chiral diimine diaza-Cope ocurre con una alta preorganización, impulsada por enlaces de hidrógeno. Esta reacción estereoselectiva procede con la inversión de la estereochemistry y excelente enantioselectivity, confirmado por la espectroscopia de CD y HPLC.

Área de la Ciencia:

Química orgánica es la química orgánica.
La estereoquímica es la estereoquímica.
Química Física es la química física.

Sus antecedentes:

Las reorganizaciones Diaza-Cope son valiosas herramientas sintéticas.
La comprensión de los mecanismos de reacción y los resultados estereoquímicos es crucial para la síntesis asimétrica.

Objetivo del estudio:

Investigar el mecanismo y el curso estereoquímico de la reorganización dirigida por H-bond dirigida por diaza-Cope en diimines quirales.
Para determinar el grado de preorganización y la enantioselectividad de la reacción.

Principales métodos:

Cristalografía de rayos X para determinar la estructura cristalina.
Análisis de la entropía de activación para evaluar la preorganización.
Espectroscopia de dicroísmo circular (CD) para el monitoreo de cambios estereoquímicos.
Cromatografía líquida de alto rendimiento (HPLC) para la determinación de la enantioselectividad.

Principales resultados:

La estructura cristalina y los datos de entropía de activación revelan un alto grado de preorganización en el reordenamiento de H-bond dirigido por diaza-Cope.
La espectroscopia de CD y los datos de HPLC demuestran la inversión de la estereoquímica.
La reacción se desarrolla con una excelente enantioselectividad.

Conclusiones:

La dirección de enlace de hidrógeno facilita un estado de transición altamente preorganizado para el reordenamiento de diaza-Cope de diimines quirales.
El mecanismo de reacción implica la inversión de la estereoquímica.
Se logra una excelente enantioselectividad, lo que pone de relieve el potencial de síntesis asimétrica.

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