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Sustitución aromática nucleofílica concertada con (19) F ((-) y (18) F ((-)
Constanze N Neumann1, Jacob M Hooker2,3, Tobias Ritter1,2,4
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Nature
|June 10, 2016
Resumen
Una nueva reacción de sustitución aromática nucleofílica concertada (CSNAr) evita las limitaciones de SNAr tradicional, permitiendo la síntesis de nuevos compuestos etiquetados con (18) F para imágenes de PET sin requerir arenas pobres en electrones.
Área de la Ciencia:
- Química orgánica
- La radioquímica
- Biología Química
Sus antecedentes:
- La sustitución aromática nucleofílica (SNAr) es un método clave para la funcionalización de las moléculas aromáticas, en particular para la introducción de flúor-18 ((18) F) para la tomografía por emisión de positrones (PET).
- Las reacciones SNR tradicionales requieren sustratos aromáticos con deficiencia de electrones para estabilizar el intermedio Meisenheimer cargado negativamente, lo que limita su alcance.
- Los métodos existentes para el marcado radiactivo (18) F a menudo implican procedimientos engorrosos como el secado azeotrópico.
Objetivo del estudio:
- Introducir una nueva reacción de sustitución aromática nucleofílica concertada (CSNAr) que supere las limitaciones del sustrato de la SNR convencional.
- Desarrollar un método tolerante al grupo funcional para la (18) F-deoxifluoración de fenoles.
- Para permitir la síntesis de diversos compuestos etiquetados con (18) F para imágenes de PET.
Principales métodos:
- Investigación de un mecanismo de reacción de desoxifluoración del fenol.
- Desarrollo y optimización de un protocolo CSNAr para la incorporación de (18) F.
- Demostración de la tolerancia del grupo funcional y síntesis de nuevas sondas de PET.
Principales resultados:
- Se identificó una reacción de CSNAr y se demostró que se produce sin un intermediario de Meisenheimer, ampliando el alcance más allá de las arenas pobres en electrones.
- Se desarrolló una nueva (18) F-deoxifluoración de fenoles, favoreciendo al CSNAr sobre el desplazamiento gradual.
- El método permite la introducción selectiva (18) de F a partir de fenoles sin secado azeotrópico, obteniendo compuestos radiomarcados anteriormente inaccesibles.
Conclusiones:
- La reacción de CSNAr proporciona una alternativa versátil a la SNR tradicional para la funcionalización aromática.
- Este nuevo enfoque simplifica la síntesis de sondas de PET etiquetadas con (18) F a partir de fenoles fácilmente disponibles.
- El método desarrollado amplía el acceso a nuevos radiotrazadores para aplicaciones de imágenes PET.
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