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Reacción catalítica asimétrica intermolecular de stetter de aldehídos heterocíclicos con nitroalquenos: la fluoración

Daniel A DiRocco¹, Kevin M Oberg, Derek M Dalton

¹Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.

Journal of the American Chemical Society

|September 3, 2009

Resumen

Desarrollamos una nueva reacción de Stetter asimétrica y catalítica utilizando aldehídos heterocíclicos y nitroalquenos. La sustitución de flúor en la columna vertebral del catalizador mejora la estereoselectividad, lo que lleva a una mejora de las enantioselectividades para varios sustratos.

Área de la Ciencia:

Química orgánica es la química orgánica.
Catalización asimétrica por catálisis asimétrica.

Sus antecedentes:

La reacción de Stetter es una valiosa reacción de formación de enlaces carbono-carbono.
El desarrollo de variantes asimétricas es crucial para la síntesis de moléculas quirales.

Objetivo del estudio:

Desarrollar una reacción Stetter intermolecular asimétrica y catalítica.
Investigar el efecto de la sustitución de flúor en la estructura y la reactividad del catalizador.

Principales métodos:

Utilizó aldehídos heterocíclicos y nitroalquenos como sustratos.
Diseñados y sintetizados precursores de carbenos N-heterocíclicos con sustitución de flúor.
Empleó cristalografía de rayos X para analizar la conformación del catalizador.

Principales resultados:

Desarrolló con éxito la reacción catalítica asimétrica intermolecular de Stetter.
Se identificó un efecto estereoelectrónico significativo de la sustitución de flúor en la estructura del catalizador.
Se observaron mejores enantioselectividades en una variedad de sustratos debido a la sustitución de flúor.

Conclusiones:

La sustitución de flúor en la columna vertebral del precursor del carbeno N-heterocíclico mejora la enantioselectividad.
Los efectos hiperconjugativos y los cambios conformacionales en el precatalizador son responsables de un mejor estereocontrol.

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