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Aminofluoración de ciclopropanos: un enfoque múltiple a través de un intermediario generado catalíticamente común

Cody Ross Pitts¹, Bill Ling¹, Joshua A Snyder¹

¹Department of Chemistry, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States.

Journal of the American Chemical Society

|May 3, 2016

Resumen

Los investigadores desarrollaron una aminofluoración regioselectiva de los ciclopropanos utilizando diversas condiciones. Un mecanismo de cadena unificador, respaldado por datos extensos y observación directa de los intermedios radicales, explica la vía de reacción.

Área de la Ciencia:

Química orgánica
La fotoquímica
Mecanismos de reacción

Sus antecedentes:

Las reacciones de aminofluoración son cruciales para la síntesis de compuestos orgánicos fluorados.
La funcionalización del ciclopropano presenta desafíos sintéticos únicos debido a la tensión del anillo.
Comprender los mecanismos de reacción es clave para optimizar las rutas sintéticas.

Objetivo del estudio:

Descubrir un método de aminofluoración altamente regioselectivo para los ciclopropanos.
Para aclarar un mecanismo unificador para esta transformación iniciada a través de varias vías.
Proporcionar pruebas espectroscópicas directas para los radicales intermedios clave.

Principales métodos:

Exploración de cuatro condiciones de reacción distintas (dos fotoquímicas y dos químicas).
Estudios de distribución de productos, análisis cinéticos, relaciones de energía libre lineal (LFER), estimaciones de Rehm-Weller, experimentos de competencia y efectos de isótopos cinéticos (KIEs).
Técnicas espectroscópicas que incluyen fluorescencia y espectroscopia de absorción de transientes, complementadas por cálculos de la teoría funcional de la densidad (DFT).

Principales resultados:

Se logra una aminofluoración altamente regioselectiva de los ciclopropanos que produce los mismos aductos en diferentes condiciones.
Propuso y justificó un mecanismo de propagación en cadena unificador que incluye un intermediario común.
Intermedios de iones radicales observados directamente mediante espectroscopia de absorción transitoria, que proporcionan apoyo cinético para el mecanismo propuesto.

Conclusiones:

Se ha establecido una aminofluoración versátil y regioselectiva de los ciclopropanos.
Un mecanismo común de propagación en cadena de radicales explica el éxito de la reacción bajo diversas condiciones de iniciación.
Los efectos del disolvente pueden influir significativamente en el paso de apertura del anillo de ciclopropano, lo que justifica una mayor investigación.

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