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Activación de C ((alquenilo) -H a través de ciclos de seis miembros: síntesis catalítica de 1,3-dieno
Mingyu Liu1, Pusu Yang1, Malkanthi K Karunananda1
1Department of Chemistry , The Scripps Research Institute , 10550 North Torrey Pines Road , La Jolla , California 92037 , United States.
Journal of the American Chemical Society
|April 10, 2018
Resumen
Este estudio introduce un nuevo método catalítico para sintetizar 1,3-dienos altamente sustituidos a partir de dos alquenos mediante la activación de C-H catalizada por el paladio. El enfoque versátil funciona con varios sustratos, incluidos los alquenos internos desafiantes.
Área de la Ciencia:
- Química orgánica
- Catálisis
- Metodología sintética
Sus antecedentes:
- Los 1,3-dienos son componentes cruciales en la síntesis orgánica.
- Los métodos anteriores para sintetizar 1,3-dienes sustituidos a menudo se enfrentan a limitaciones en el alcance y la eficiencia del sustrato.
- Los alquenos no conjugados internos son sustratos particularmente difíciles para las estrategias de activación de C-H.
Objetivo del estudio:
- Desarrollar un nuevo método catalítico para la síntesis de 1,3-dienos altamente sustituidos.
- Para utilizar una estrategia de activación dirigida, mediada por el paladio (C) (alquenilo) -H.
- Ampliar el alcance del sustrato para la síntesis de 1,3-dieno, incluidos los alquenos internos desafiantes.
Principales métodos:
- Se empleó una estrategia de activación de C (alquenilo) H catalizada por paladio (II).
- Se utilizaron tres clases de sustratos con auxiliares bidentados: ácidos 4-pentenoicos, alcoholes alílicos y aminas bisomoalílicas.
- La rotación catalítica se logró utilizando dióxido de manganeso (MnO2) o una combinación de cobalto (II) acetato (Co) y oxígeno (O2).
Principales resultados:
- El método preparó con éxito 1,3-dienes altamente sustituidos a partir de dos alquenos diferentes.
- La transformación demostró un amplio alcance en todas las clases de sustrato probadas.
- Los alquenos no conjugados internos, anteriormente sustratos difíciles, fueron tolerados.
- Los estudios experimentales y computacionales aclararon el mecanismo de reacción y la selectividad.
- Se aisló y caracterizó un único intermediario de dímeros de alquenilpaladio.
Conclusiones:
- Se ha establecido un método catalítico versátil y eficiente para sintetizar 1,3-dienos altamente sustituidos.
- La estrategia de activación de C ((alceno) H desarrollada supera las limitaciones de los métodos anteriores, en particular con alquenos internos.
- El estudio proporciona información mecanicista sobre la síntesis de dieno catalizada por el paladio.
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