Las silaciclopropanaciones diastereoselectivas de alquenos quirales funcionalizados
Tom G Driver1, Annaliese K Franz, K A Woerpel
1Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
Journal of the American Chemical Society
|June 6, 2002
Resumen
La reducción de litio y la transferencia térmica de silileno permiten silaciclopropanaciones altamente diastereoselectivas de las olefinas quirales. Los factores estéricos, no los efectos del oxígeno, dictan la reacción.
Área de la Ciencia:
- Química del organosilicio Química del organosilicio
- Síntesis estereoselectiva de síntesis.
- Síntesis orgánica La síntesis orgánica.
Sus antecedentes:
- Los siliclopropanos son valiosos intermediarios sintéticos.
- El desarrollo de métodos diastereoselectivos para su síntesis es crucial.
Objetivo del estudio:
- Para explorar la reducción de litio y la transferencia de silileno térmico para la silaciclopropanación diastereoselectiva.
- Para investigar el control estereoquímico en estas reacciones.
Principales métodos:
- Reducción de litio de di-tert-butildiclorosilano.
- Reacciones de transferencia de silileno térmico a 105-125°C.
- Silaciclopropanación de olefinas quirales funcionalizadas que incluyen ciclohexenas, ciclopentenos, norbornenos y alquenos 1,1-disubstituidos.
Principales resultados:
- Se logró una silaciclopropanación altamente diastereoselectiva (92:8 a >99:1).
- Se demostró que las interacciones estéricas controlan el resultado estereoquímico, anulando los posibles efectos que dirigen el oxígeno.
- Se identificaron limitaciones de la transferencia térmica de silileno para ciertos sustratos debido a temperaturas elevadas.
Conclusiones:
- La reducción de litio y la transferencia térmica de silileno son complementarias y efectivas para la silaciclopropanación diastereoselectiva.
- El volumen estérico del intermedio silileno es el principal determinante de la diastereoselectividad.
- Los silicaciclopropanos funcionalizados se pueden elaborar en productos complejos polioxigenados.
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