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El cierre del anillo y la metátesis de enyne: control sobre la selectividad del modo y la estereoselectividad
1Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
Journal of the American Chemical Society
|November 19, 2004
Resumen
El cierre del anillo y la metástasis de las enine forman eficientemente macrociclos. La atmósfera de etileno mejora la selectividad para los endoproductos y los isómeros E/Z en dienes macrocíclicos.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis es la catálisis.
- Química sintética de la química sintética.
Sus antecedentes:
- La metátesis de cierre de anillo enyne es una herramienta poderosa para la síntesis de macrociclos.
- El control de la selectividad en la macrociclación sigue siendo un desafío.
Objetivo del estudio:
- Desarrollar un método selectivo para la síntesis de anillos de 10-15 miembros a través de la metátesis de cierre de anillos.
- Investigar los factores que influyen en la selectividad exo/endo y E/Z.
Principales métodos:
- Utilizó enlaces derivados del tartarato para conectar una y otra subunidad.
- Reacciones de metátesis de cierre de anillo de enyne realizadas en condiciones variables, incluida la atmósfera de etileno.
- Se analizó la selectividad del producto en función del tamaño del anillo y las condiciones de reacción.
Principales resultados:
- El tamaño del anillo dicta la selectividad exo/endo: anillos más grandes (12-15) favorecen el endo, anillos más pequeños (5-11) favorecen el exo.
- La atmósfera de etileno mejora significativamente tanto la selectividad exo/endo como la selectividad E/Z de los dienes macrocíclicos.
- El etileno induce metástasis cruzada, lo que lleva a la metástasis de dieno que forma exclusivamente endoproductos con alta E-selectividad.
Conclusiones:
- La metátesis de cierre de anillo enyne es una ruta viable a los macrociclos.
- La atmósfera de etileno es crucial para lograr una alta selectividad en la macrociclización a través de este método.
- El método descrito ofrece un control preciso sobre la síntesis de dieno macrocíclico.
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