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Ciclización aniónica de una enediína conjugada cruzada

Lior Eshdat¹, Harald Berger, Henning Hopf

¹Department of Organic Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.

Journal of the American Chemical Society

|April 11, 2002

Resumen

Los investigadores demostraron una nueva ciclización aniónica de enediinas conjugadas cruzadas, formando un anillo de cinco miembros bajo condiciones reductivas. Este método supera las limitaciones de la cicloaromatización tradicional de Bergman al generar un número Hückel de electrones pi.

Área de la Ciencia:

Química orgánica es la química orgánica.
Química sintética de la química sintética.

Sus antecedentes:

Las enediinas cruzadas típicamente no se someten a la cicloaromatización de Bergman debido a la insuficiencia de electrones pi.
Las condiciones reductivas pueden permitir la ciclización mediante la formación de productos con un número Hückel de pi electrones.

Objetivo del estudio:

Para ilustrar y demostrar una ciclización aniónica de enediinas conjugadas cruzadas.
Para lograr la formación de un anillo de cinco miembros a través de este método novedoso.

Principales métodos:

Reducción del 9-(3-fenil-1-feniletinipropil-2-inilideno)-9H-fluoreno (3) mediante el uso de potasio.
La generación del dianión de 9-(3,4-difenilciclopenta-2,4-dienilideno)-9H-fluoro (4(2-)).
Oxidación del dianión con yodo.

Principales resultados:

Se demostró con éxito una ciclización aniónica de un enediyne. conjugado cruzado.
Formación de un anillo de cinco miembros que contiene un fragmento de ciclopentadienilo.
Aislamiento de un producto de fulvaleno inestable (4).

Conclusiones:

La ciclización aniónica bajo condiciones reductivas es una estrategia viable para las enediinas cruzadas conjugadas.
Este enfoque supera las limitaciones electrónicas de la cicloaromatización de Bergman.
El estudio presenta la primera ciclización aniónica de una enediina conjugada cruzada que produce un anillo de cinco miembros.

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