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Se trata de una ciclización de Nazarov asimétrica y organocatalítica

Ashok K Basak¹, Naoyuki Shimada, William F Bow

¹Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu, Hawaii 96822, USA.

Journal of the American Chemical Society

|May 29, 2010

Resumen

Un nuevo método organocatalítico permite la ciclización asimétrica de Nazarov de las diquetoesteras. Este enfoque de activación dual produce productos cíclicos con estereocentros cuaternarios adyacentes con alta selectividad y exceso enantiomérico.

Área de la Ciencia:

Química orgánica es la química orgánica.
Catalización asimétrica por catálisis asimétrica.

Sus antecedentes:

La ciclización de Nazarov es una reacción clave para la formación de ciclopentenonas.
El desarrollo de variantes asimétricas es crucial para la síntesis de moléculas quirales.

Objetivo del estudio:

Desarrollar una ciclización organocatalítica asimétrica de Nazarov de los dicetoesters.
Para lograr una alta estereoselectividad y un exceso enantiomérico en los productos de ciclización.

Principales métodos:

Cribado de varios organocatalizadores, lo que lleva a la identificación de un nuevo catalizador de tiourea.
Utilizando un mecanismo de activación dual para la reacción de ciclización.
Desarrollo de una síntesis conveniente para los materiales de partida del dicetoester acíclico a través de la adición nucleofílica a un ceteno.

Principales resultados:

El método desarrollado realiza con éxito la ciclización organocatalítica asimétrica de Nazarov de diquetoesters.
La reacción produce productos cíclicos con dos átomos de carbono cuaternarios asimétricos adyacentes con alta diastereoselectividad.
Se logró un excelente exceso enantiomérico (ee) para los productos cíclicos quirales.
Se estableció una síntesis eficiente de los precursores del diketoester.

Conclusiones:

Se ha establecido una ciclización de Nazarov organocatalítica asimétrica novedosa y eficiente.
El método proporciona acceso a valiosos compuestos cíclicos con múltiples estereocentros.
El mecanismo de activación dual y el diseño del catalizador son clave para el éxito de la reacción.

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