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Adición catalítica de ciclo de paladio-oxalilo
Barry M Trost1, Zhongxing Huang2, Ganesh M Murhade2
1Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA. bmtrost@stanford.edu.
Science (New York, N.Y.)
|November 3, 2018
Resumen
Los investigadores desarrollaron una nueva cicloadición (3+2) catalizada por el paladio utilizando un intermediario Pd-oxalilo. Este método sintetiza de manera eficiente diversos esqueletos de tetrahidrofurano, superando las limitaciones de la química tradicional de los cationes de oxyallyl.
Área de la Ciencia:
- Síntesis orgánica
- Catálisis
- Química medicinal
Sus antecedentes:
- Las reacciones de cicloadición quimioselectivas son cruciales para la construcción de sistemas complejos de anillos en la síntesis orgánica.
- Los cationes oxalilo suelen someterse a cicloadiciones (4 + 3), lo que limita su utilidad en la formación de anillos de cinco miembros.
- El desarrollo de nuevas vías sintéticas para acceder a esqueletos de cinco miembros sigue siendo un desafío importante.
Objetivo del estudio:
- Explorar nuevas reacciones de cicloadición para sintetizar sistemas de anillos de cinco miembros.
- Investigar el uso de la catálisis del paladio en la química de los cationes de oxalilo.
- Desarrollar un método para acceder a esqueletos de tetrahidrofurano a través de una vía de cicloadición (3+2).
Principales métodos:
- Generación de un intermediario de paladio-oxalilo a partir de un precursor adaptado mediante el uso de un catalizador Pd (0).
- Reacción del intermediario Pd-oxalilo con dienos conjugados en una cicloadición (3+2).
- Conversión posterior catalizada por el paladio de los aductos de tetrahidrofurano a las ciclopentanonas.
Principales resultados:
- Se logró una nueva reacción de cicloadición catalizada por Pd (3+2), que produjo diversos esqueletos de tetrahidrofurano.
- La reacción procede por una vía escalonada que implica la transferencia de Pd-alilo y el cierre del anillo, prevaleciendo sobre la selectividad convencional (4 + 3).
- Los heterociclos resultantes pueden transformarse fácilmente en ciclopentanonas carbocíclicas.
Conclusiones:
- Este estudio presenta una nueva estrategia para acceder a los anillos de cinco miembros utilizando catálisis de paladio.
- El método desarrollado ofrece una vía versátil para los tetrahidrofuranos y las ciclopentanonas sustituidos.
- Este enfoque amplía la utilidad sintética de los intermediarios de oxyallyl en la química orgánica.
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