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La alquilación intramolecular catalizada por platino de los indoles con olefinas no activadas
Cong Liu1, Xiaoqing Han, Xiang Wang
1P. M. Gross Chemical Laboratory, Duke University, Durham, North Carolina 27708-0346, USA.
Journal of the American Chemical Society
|March 25, 2004
Resumen
La catálisis de platino permite una síntesis eficiente de derivados de carbazoles a partir de indoles de 2-alquenilo. Este método es versátil, tolera varias sustituciones y es aplicable a los indolos no protegidos y a los heterociclos relacionados.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis es la catálisis.
- Química Heterocíclica La Química Heterocíclica es una de las más conocidas.
Sus antecedentes:
- Los derivados del indole son andamios cruciales en la química medicinal.
- Las rutas sintéticas eficientes para complejos heterociclos basados en indol son muy buscadas.
- La catálisis de platino ofrece una reactividad única para la formación de enlaces C-C.
Objetivo del estudio:
- Desarrollar un nuevo método de ciclización catalizado por platino para indolos 2-alquenilo.
- Explorar el alcance y las limitaciones de este sistema catalítico.
- Para dilucidar el mecanismo de reacción.
Principales métodos:
- Reacción del 1-metil-2-(4-pentenil) indol con el cloruro de platino (PtCl2) y el catalizador.
- Uso del dioxano como disolvente con trazas de ácido clorhídrico (HCl).
- Estudios mecánicos que involucran el ataque nucleófilo a las olefinas complejas de platino.
Principales resultados:
- Aislamiento de alto rendimiento (92%) de 4,9-dimetil-2,3,4,9-tetrahidro-1H-carbazole.
- Tolerancia de las sustituciones en la cadena pentenila.
- Síntesis exitosa de las tetrahidro-beta-carbolinonas.
- Se observó una regioselectividad exclusiva de 6-endo-trig observada para 2-(3-butenil) indoles.
- Demostración de la aplicabilidad a los indoles sin protección.
Conclusiones:
- La ciclización catalizada por platino proporciona una ruta eficiente a los carbazoles sustituidos y a los heterociclos relacionados.
- El protocolo es robusto, versátil y procede a través del ataque nucleófilo del indol sobre una olefina coordinada.
- Esta metodología amplía el conjunto de herramientas sintéticas para acceder a complejos heterociclos que contienen nitrógeno.
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