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Las estructuras de solución de los aminoalcóxidos de litio utilizados en las 1,2-adiciones altamente

Angela M Bruneau¹, Lara Liou, David B Collum

¹Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University , Ithaca, New York 14853-1301, United States.

Journal of the American Chemical Society

|January 30, 2014

Resumen

Los efedratos de litio y los aminoalóxidos de litio derivados del norcarano forman estructuras tetraméricas, lo que permite adiciones altamente enantioselectivas de 1,2. Estos auxiliares quirales exhiben núcleos cúbicos simétricos S4, cruciales para la síntesis a gran escala.

Área de la Ciencia:

Química organometálica de las sustancias orgánicas.
Síntesis asimétrica en síntesis asimétrica.
Los auxiliares de la quiral también lo son.

Sus antecedentes:

Los efedratos de litio y los aminoalcoxidos de litio derivados del norcarano son eficaces auxiliares quirales.
Su estado de agregación y estructura son críticos para las reacciones enantioselectivas.

Objetivo del estudio:

Para caracterizar la agregación y la estructura de los efedratos de litio y los alcóxidos de litio amino derivados del norcarano.
Comprender su papel en las adiciones enantioselectivas de 1,2 a gran escala.

Principales métodos:

Método de variaciones continuas.
(6) La espectroscopia de RMN de litio.
Teoría funcional de la densidad (DFT) cálculos.
Cristalografía de rayos X con rayos X.

Principales resultados:

Los aminoalcóxidos de litio existen como agregados tetrámeros.
La RMN de Li a baja temperatura (6) reveló homoagregados estereoisoméricamente puros.
Los agregados poseen un núcleo cúbico simétrico S4, confirmado por DFT y datos de rayos X.

Conclusiones:

El núcleo cúbico simétrico S4 es clave para la eficacia de estos aminoalcóxidos de litio como auxiliares quirales.
La comprensión de la estructura agregada proporciona información sobre el control de la enantioselectividad en reacciones a gran escala.

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