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La aminación C-H intramolecular estereospecífica estereospecífica de las sales de 1-aza-2-azoniaaleno
Daniel A Bercovici1, Matthias Brewer
1Department of Chemistry, The University of Vermont, 82 University Place, Burlington, Vermont 05405, USA.
Journal of the American Chemical Society
|June 12, 2012
Resumen
Los nuevos productos de pirazolina se sintetizan utilizando sales de 1-aza-2-azoniaaleno en reacciones de aminación C-H intramoleculares. Este método funciona de manera eficiente varias posiciones de carbono mientras se preserva la pureza enantiomérica.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Química sintética de la química sintética.
Sus antecedentes:
- Las sales de 1-aza-2-azoniaaleno son productos reactivos intermedios.
- La aminación C-H intramolecular es una transformación sintética valiosa.
Objetivo del estudio:
- Para explorar la utilidad de las sales de 1-aza-2-azoniaaleno en la aminación C-H intramolecular.
- Para sintetizar los productos de pirazolina de manera eficiente y estereoselectivamente.
Principales métodos:
- Generación de sales de 1-aza-2-azoniaaleno a partir de compuestos α-cloroazo utilizando ácidos halófilos de Lewis.
- Reacciones de aminación C-H intramoleculares dirigidas a las posiciones bencílicas y terciarias alifáticas.
Principales resultados:
- Los productos de pirazolina se obtuvieron en rendimientos de buenos a excelentes.
- La aminación procedió eficientemente tanto en enlaces bencílicos como en enlaces C-H alifáticos terciarios.
- El exceso enantiomérico se mantuvo durante las reacciones en los centros quirales.
- Una reacción de competencia indicó la inserción preferente en posiciones bencílicas ricas en electrones.
Conclusiones:
- Las sales de 1-aza-2-azoniaaleno son intermediarios efectivos para la aminación C-H intramolecular.
- La reacción procede a través de un mecanismo de inserción concertado, que probablemente involucra un intermediario iónico similar al nitrenio.
- Esta metodología ofrece una ruta estereoselectiva a los derivados de la pirazolina.
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