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Isomerización regioselectiva de epoxidos 2,3-disubstituidos a cetonas: una alternativa a la oxidación de Wacker de

Jessica R Lamb¹, Michael Mulzer¹, Anne M LaPointe¹

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

Journal of the American Chemical Society

|November 3, 2015

Resumen

Este estudio introduce una nueva alternativa de oxidación de Wacker para las olefinas internas, utilizando la epoxidación y la isomerización para producir cetonas con altos rendimientos. El método también permite la resolución cinética de los trans-epoxidos, ofreciendo una valiosa selectividad para sustratos específicos.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

La oxidación de Wacker es un proceso industrial clave para convertir las olefinas en cetonas.
Los métodos existentes para la oxidación interna de las olefinas pueden carecer de regioselectividad o requerir condiciones duras.
El desarrollo de vías de oxidación alternativas y más suaves es crucial para una síntesis orgánica eficiente.

Objetivo del estudio:

Establecer una vía catalítica alternativa para la oxidación interna de las olefinas.
Para lograr una alta regioselectividad en la formación de cetonas.
Explorar la aplicación de este sistema catalítico en la resolución cinética de los epóxidos.

Principales métodos:

Epoxidación de los transalquenos.
Isomerización leve y regioselectiva de los epóxidos en cetonas.
Resolución cinética de los trans-epoxidos utilizando un sistema catalítico similar.
Estudios preliminares de etiquetado cinético e isotópico para elucidar el mecanismo de reacción.

Principales resultados:

Se obtiene un rendimiento de 66-98% de los principales isómeros cetónicos de las olefinas internas.
Se ha demostrado una alta regioselectividad en la etapa de isomerización.
Se obtienen factores de selectividad sintéticamente útiles de 17-23 para los transepoxidos sustituidos por bencilo.
Identificación de la apertura del anillo de epóxido como el paso probable para limitar el volumen de negocios.

Conclusiones:

El método desarrollado ofrece una alternativa eficaz a la oxidación tradicional de Wacker para las olefinas internas.
El sistema catalítico es versátil, aplicable tanto a la oxidación de olefinas como a la resolución cinética del epoxido.
Otros estudios mecanicistas confirmaron la vía propuesta que involucra a los productos intermedios de epóxido.

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