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Cicloadición catalítica [4+2] dicyanativa desencadenada por la cianopaladación de eninas conjugadas bajo condiciones

Shigeru Arai¹, Yuka Koike, Hirohiko Hada

¹Graduate School of Pharmaceutical Sciences, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan. arai@p.chiba-u.ac.jp

Journal of the American Chemical Society

|March 18, 2010

Resumen

Una nueva reacción catalizada por el paladio permite la síntesis eficiente de complejos anillos de ciclohexeno. Esta cicloadición dicyanativa forma múltiples enlaces carbono-carbono y estereocentros en un solo paso, ofreciendo una poderosa herramienta para la síntesis orgánica.

Área de la Ciencia:

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

Sus antecedentes:

Las reacciones catalizadas por el paladio son cruciales en la síntesis orgánica moderna.
Las reacciones de cicloadición son fundamentales para la construcción de estructuras cíclicas.
Los métodos eficientes para la formación de múltiples enlaces C-C y estereocentros son muy buscados.

Objetivo del estudio:

Para desarrollar una nueva reacción de dicyanato [4+2] cícloadición catalizada por paladio.
Para utilizar las dieninas y el cianuro de trimetilsililo (TMSCN) fácilmente disponibles.
Para lograr la formación de anillos de ciclohexeno altamente funcionales y múltiples estereocentros.

Principales métodos:

Se empleó un catalizador de paladio para mediar la reacción entre dieninas y TMSCN.
La reacción se lleva a cabo a través de la cianopaladación de los alcinos terminales, formando intermedios pi-allilo Pd.
Los siguientes pasos de ciclización de 5 exos y 6 endos conducen a los productos deseados.
Se utilizaron condiciones aeróbicas para el ciclo catalítico.

Principales resultados:

El protocolo formó con éxito cuatro enlaces C-C en una sola operación.
Se construyeron anillos de ciclohexeno altamente funcionales.
Se generaron cinco centros estereogénicos contiguos en un solo paso.
La reacción intermolecular con el acrilato de metilo produjo carbociclos multifuncionalizados con regioselectividad.

Conclusiones:

Este estudio presenta una eficiente y versátil dicyanativa [4+2] cícloadición catalizada por el paladio.
La reacción ofrece una poderosa estrategia para la construcción de complejos marcos carbocíclicos.
El método proporciona acceso a valiosos intermedios sintéticos con un alto control estereoquímico.

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