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A Protocol for Safe Lithiation Reactions Using Organolithium Reagents
Published on: November 12, 2016
Vinilación intramolecular de los organolitios secundarios y terciarios
Julien Lefranc1, Anne M Fournier, Gaëlle Mingat
1School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
Journal of the American Chemical Society
|April 7, 2012
Resumen
Los carbaniones benzílicos de las ureas, los carbamatos y los tiocarbamatos migran los grupos alquenilo intramolecularmente. Esta reacción crea valiosas aminas alilicas con nuevos estereocentros, útiles en la síntesis orgánica.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La síntesis estereoselectiva de síntesis.
Sus antecedentes:
- Los carbaniones bencílicos son versátiles intermediarios en la síntesis orgánica.
- Las reorganizaciones intramoleculares ofrecen rutas eficientes a moléculas complejas.
Objetivo del estudio:
- Investigar la migración intramolecular del grupo alquenilo de los carbaniones bencílicos derivados de ureas, carbamatos y tiocarbamatos.
- Explorar el resultado estereoquímico y la utilidad sintética de este reordenamiento para generar productos enriquecidos enantioméricamente.
Principales métodos:
- Deprotonación de las ureas bencílicas sustituidas por N'-alquenilo, los carbamatos y los tiocarbamatos.
- Solubilidad de los productos de urea resultantes.
- Análisis estereoquímico de los productos.
- Estudios computacionales y de espectroscopia de infrarrojos (IR) in situ.
Principales resultados:
- Los carbaniones generados a partir de estos sustratos sufren una fácil migración intramolecular del grupo alquenilo.
- La disolución de los productos de urea produce aminas α-alqueinizadas.
- Los materiales de partida enantioméricamente puros producen aminas alilicas con centros estereogénicos cuaternarios alilicos N-portantes en una forma enriquecida enantioméricamente.
- La reacción procede a través de una vía concertada de adición-eliminación.
Conclusiones:
- El estudio demuestra un nuevo reordenamiento estereospecífico para la síntesis de aminas enriquecidas enantioméricamente con α-alqueiniladas.
- Este método proporciona acceso a bloques de construcción valiosos que contienen estereocentros cuaternarios alelicos.
- Los hallazgos ofrecen información sobre el mecanismo de esta importante transformación orgánica.
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