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Una reacción oxidativa Heck intermolecular general y altamente selectiva controlada por quelantes

Jared H Delcamp¹, Alexandria P Brucks, M Christina White

¹University of Illinois Urbana-Champaign, 600 S. Mathews, Urbana, Illinois 61801, USA.

Journal of the American Chemical Society

|August 2, 2008

Resumen

Una nueva reacción oxidativa de Heck que utiliza un catalizador de paladio/bis-sulfóxido permite una síntesis eficiente de olefinas internas de varios sustratos. Este método ofrece una alta selectividad y evita reacciones secundarias comunes, por lo que es valioso para la síntesis de moléculas complejas.

Área de la Ciencia:

Química orgánica es la química orgánica.
La catálisis es la catálisis.
Metodología sintética de la metodología sintética.

Sus antecedentes:

La reacción de Heck es una herramienta poderosa para la formación de enlaces carbono-carbono.
La isomerización del paládio-hidruro (Pd-H) es una reacción secundaria común en las reacciones de Heck, limitando la estereoselectividad.
El desarrollo de metodologías de reacción de Heck selectivas y ampliamente aplicables sigue siendo un objetivo importante en la síntesis orgánica.

Objetivo del estudio:

Para informar sobre una nueva reacción oxidativa intermolecular controlada por quelato de Heck.
Para demostrar la eficacia de la reacción con una amplia gama de sustratos y reactivos.
Para lograr altos rendimientos y excelentes selectividades regionales y estereos en la formación de olefinas internas.

Principales métodos:

Utilizando un complejo de paladio/bis-sulfóxido (1) como catalizador.
Empleando sustratos de α-olefinas estabilizados sin resonancia y reactivos de organoboron.
Llevar a cabo la reacción en condiciones oxidativas leves.

Principales resultados:

La reacción procede con una amplia gama de socios de acoplamiento, ofreciendo productos internos de olefinas en buenos rendimientos.
Se lograron estereoselectividades regionales y E:Z (>20:1) sobresalientes, sin isomerización Pd-H observada.
El sistema catalítico demostró tolerancia a los alcoholes no protegidos y preservó la pureza óptica en los centros estereogénicos proximales.

Conclusiones:

Se ha desarrollado una nueva y altamente selectiva reacción oxidativa intermolecular de Heck.
La reacción catalizada por Pd/bis-sulfóxido ofrece una vía suave y eficiente a las olefinas internas.
Se prevé que esta metodología sea ampliamente aplicable en la síntesis de moléculas complejas debido a su amplio alcance y alta selectividad.

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