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Una dicotomía mecanicista en la reactividad del alcohol de propargilo catalizado por rutenio: una nueva ciclización
Barry M Trost1, Michael T Rudd
1Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA. bmtrost@stanford.edu
Journal of the American Chemical Society
|September 18, 2003
Resumen
Los catalizadores de rutenio facilitan la ciclización del dieno-ol para formar cicloalquenos. Una nueva vía que implica la adición de agua crea 1-acilcicloalquenos, lo que demuestra una amplia aplicabilidad para la síntesis de anillos de cinco y seis miembros.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Síntesis orgánica La síntesis orgánica.
- La catálisis de la catálisis.
Sus antecedentes:
- Se sabe que los catalizadores de rutenio median las reacciones de cicloisomerización de diyne-ols.
- Los mecanismos existentes a menudo involucran intermediarios de rutenaciclopentadieno.
- Se planteó la hipótesis de una posible vía de competencia que involucra la adición de agua a los sustratos primarios de alcohol.
Objetivo del estudio:
- Investigar la viabilidad de una vía de adición de agua en ciclizaciones de dieno-ol catalizadas por rutenio.
- Explorar el alcance y la selectividad de este nuevo proceso de ciclización hidrática.
- Aclarar los detalles mecánicos que diferencian las vías de reacción basadas en la sustitución de alcohol.
Principales métodos:
- Reacciones catalizadas por rutenio de varios sustratos diine-ol en presencia de agua.
- Síntesis y caracterización de productos utilizando técnicas como la espectroscopia de RMN.
- Estudios mecanicistas para sondear las vías de reacción y la selectividad.
Principales resultados:
- Demostró una vía general para la formación de 1-acilcicloalquenos de cinco y seis miembros a través de la ciclización hidrática.
- Se observó la adición de agua por quimioselección a las alquinas menos obstaculizadas en diynes asimétricas.
- Mostró una alta selectividad en la competencia de alquinas sustituidas por metilo frente al etil y la preservación de enlaces dobles y epóxidos.
Conclusiones:
- Dos variedades de reacción distintas operan en ciclizaciones de diine-ol catalizadas por rutenio, dependientes de la sustitución de alcohol.
- La ciclización hidrática ofrece una ruta versátil a los cicloalquenos funcionalizados.
- La reacción exhibe un notable control sobre la regioselectividad y la estereoquímica.
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