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Acceso a múltiples clases de 2 H-indazoles: implicaciones mecánicas para las reacciones de Cadogan y Davis-Beirut

Jie S Zhu¹, Clarabella J Li¹, Ka Yi Tsui¹

¹Department of Chemistry , University of California Davis , 1 Shields Avenue , Davis , California 95616 , United States.

Journal of the American Chemical Society

|March 27, 2019

Resumen

El ciclo de Cadogan

Área de la Ciencia:

Química orgánica
Química Heterocíclica

Sus antecedentes:

La ciclización de Cadogan es un método común para sintetizar 2H-indazoles.
El mecanismo generalmente involucra productos intermedios de nitreno, pero se teorizaron vías que no son de nitreno.
Los heterociclos de nitrógeno son valiosos en diversas aplicaciones químicas.

Objetivo del estudio:

Para investigar las vías no-nitrónicas en la ciclización de Cadogan.
Para sintetizar y caracterizar los intermediarios oxigenados en la reacción.
Desarrollar condiciones más suaves para la síntesis de 2H-indazol.

Principales métodos:

Se interrumpió la reacción Cadogan/Davis-Beirut para sintetizar 2H-indazol N-óxidos.
Aislamiento y caracterización de los óxidos de nitrógeno sintetizados.
Estudios mecánicos para elucidar las vías de reacción.

Principales resultados:

Se han sintetizado y caracterizado con éxito los N-óxidos de 2H-indazol.
Se proporcionan pruebas directas de los intermediarios oxigenados en la reacción.
Se ha demostrado una ciclización formal de Cadogan a temperatura ambiente.

Conclusiones:

Los intermediarios oxigenados son competentes en Cadogan y reacciones relacionadas.
El estudio ofrece nuevos conocimientos mecanicistas sobre estas ciclizaciones.
Se logró una síntesis a temperatura ambiente de 2H-indazoles, ofreciendo una alternativa más suave.

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