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Reorganizaciones enantioselectivas de Claisen con un catalizador donante de enlace de hidrógeno

Christopher Uyeda¹, Eric N Jacobsen

¹Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.

Journal of the American Chemical Society

|June 26, 2008

Resumen

Un nuevo catalizador de iones de guanidinium promueve efectivamente las reorganizaciones [3,3]-sigmatrópicas en éteres de vinilo alilo. Un derivado simétrico de C2 logra reordenamientos catalíticos Claisen altamente enantioselectivos para sustratos sustituidos por ésteres.

Área de la Ciencia:

Química orgánica es la química orgánica.
La catálisis de la catálisis.
Síntesis asimétrica de síntesis.

Sus antecedentes:

El reordenamiento [3,3]-sigmatrópico, en particular el reordenamiento de Claisen, es una reacción fundamental de formación de enlaces carbono-carbono en la síntesis orgánica.
El desarrollo de catalizadores eficientes y selectivos para estas transformaciones es crucial para la construcción de arquitecturas moleculares complejas.
Los iones de guanidinium han surgido como catalizadores prometedores debido a sus fuertes capacidades de enlace de hidrógeno.

Objetivo del estudio:

Investigar la actividad catalítica del ion N,N'-difenilguanidinio con un contador BArF no coordinador para las reorganizaciones [3,3]-sigmatrópicas de éteres de vinilo aliloides.
Desarrollar y evaluar un nuevo derivado de iones de guanidinio simétrico C2 para los reordenamientos catalíticos Claisen altamente enantioselectivos de éteres de vinilo alilo-vinilo sustituidos por ésteres.

Principales métodos:

Utilizó el ión N,N'-difenilguanidinium emparejado con el contraión BArF para catalizar el reordenamiento [3,3]-sigmatrópico de varios éteres de vinilo alilo sustituidos.
Sintetizó un nuevo derivado de iones de guanidinio C2-simétrico.
Empleó el catalizador de iones de guanidinium C2-simétrico para las reorganizaciones enantioselectivas Claisen de éteres de vinilo alilo sustituidos por ésteres.

Principales resultados:

N,N'-Diphenylguanidinium/BArF demostró su eficacia como catalizador para el reordenamiento [3,3]-sigmatrópico de diversos éteres de vinilo de alilo.
El recién desarrollado derivado simétrico de iones de guanidinio C2 permitió reordenamientos catalíticos Claisen altamente enantioselectivos de éteres de vinilo alilo sustituidos por ésteres.

Conclusiones:

El ion N,N'-Diphenylguanidinium es un catalizador eficaz para las reorganizaciones sigmatrópicas [3,3]-sigmatrópicas.
El derivado simétrico de iones de guanidinio C2 representa un avance significativo en el logro de reordenamientos Claisen enantioselectivos, ofreciendo una herramienta valiosa para la síntesis asimétrica.

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