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Adición enantioselectiva catalizada por cobre de las enenas a las cetonas

Xiao-Feng Wei¹, Xiao-Wei Xie¹, Yohei Shimizu¹

¹Graduate School of Pharmaceutical Sciences, The University of Tokyo , Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

Journal of the American Chemical Society

|March 21, 2017

Resumen

Un nuevo método catalizado por cobre permite la adición enantioselectiva de eninas omitidas a las cetonas. Esto crea valiosos alcoholes quirales terciarios con alta selectividad y tolerancia al grupo funcional.

Área de la Ciencia:

Química orgánica
Catálisis
Síntesis asimétrica

Sus antecedentes:

Los alcoholes terciarios son componentes cruciales en la síntesis orgánica.
Es muy deseable desarrollar métodos enantioselectivos para su síntesis.
Las eninas omitidas ofrecen potencial como pronucleófilos estables, pero requieren estrategias de activación específicas.

Objetivo del estudio:

Desarrollar una nueva adición enantioselectiva catalizada por el cobre de las eninas omitidas a las cetonas.
Para utilizar las eninas omitidas como pronucleófilos estables de hidrocarburos para la construcción de alcoholes terciarios quirales.
Para lograr altos niveles de estereocontrol y quimioselectividad en la reacción de adición.

Principales métodos:

Utilizando un catalizador de base Brønsted conjugado con cobre (I) en combinación con un ligando quiral de difosfina, (S,S) -Ph-BPE.
Utilizando la desprotonación quimioselectiva de las eninas omitidas sobre los α-protones más ácidos de las cetonas.
Caracterización de los productos alcohólicos terciarios enriquecidos enantioméricamente y análisis de la estereoquímica de la reacción.

Principales resultados:

Adición enantioselectiva exitosa de eninas omitidas a una gama de cetonas.
Alto enriquecimiento enantiomérico y diastereoselectividad en los alcoholes terciarios resultantes.
Se ha demostrado una excelente generalidad del sustrato y tolerancia del grupo funcional.
Conversión exclusiva de las fracciones de eninas omitidas a eninas cis-conjugadas, permitiendo nuevas transformaciones.

Conclusiones:

Se ha establecido un método fácil y eficiente para sintetizar alcoholes terciarios enantioméricamente enriquecidos a partir de eninas y cetonas omitidas.
El sistema catalítico desarrollado muestra una notable selectividad, superando los desafíos asociados con la acidez del sustrato.
Las eninas cis-conjugadas resultantes sirven como intermedios versátiles para posteriores manipulaciones sintéticas.

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