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El cobre altamente enantioselectivo ((I) -fesulfos-catalizado 1,3-dipolar cicloadición de los ylidos de azometina

Silvia Cabrera¹, Ramón Gómez Arrayás, Juan C Carretero

¹Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.

Journal of the American Chemical Society

|November 25, 2005

Resumen

Un nuevo catalizador quiral de ácido de Lewis impulsa eficientemente las reacciones asimétricas de cicloadición 1,3-dipolar. Este sistema logra altos rendimientos y una enantioselectividad excepcional para los ylidos de azometina, incluso con sustratos derivados de la ketimina.

Área de la Ciencia:

Química orgánica es la química orgánica.
La catálisis es la catálisis.
Síntesis asimétrica de síntesis.

Sus antecedentes:

Los ylidos de azometina son versátiles 1,3-dipolos utilizados en la síntesis orgánica.
Las cicloadiciones catalíticas asimétricas 1,3-dipolares son cruciales para crear moléculas quirales.
Desarrollar catalizadores eficientes y selectivos para estas reacciones sigue siendo un desafío clave.

Objetivo del estudio:

Desarrollar un catalizador quiral de ácido de Lewis altamente eficiente para reacciones asimétricas de cicloadición 1,3-dipolar.
Investigar el alcance y las limitaciones de este sistema catalítico con varios sustratos de azometina y dipolarófilos.
Informar sobre la primera cicloadición asimétrica catalítica exitosa con azometinas derivadas de la ketimina.

Principales métodos:

Formación de un sistema catalizador utilizando Cu(CH3CN) 4ClO4 y el ligando planar quiral P,S-Fesulphos.
Aplicación del catalizador en la cicloadición 1,3-dipolar de ylidos de azometina.
Análisis de los productos de reacción para el rendimiento, la diastereoselectividad (endoaductos) y la enantioselectividad (ee%).

Principales resultados:

El sistema de catalizador Cu(I) -Fesulfos demostró una alta eficiencia como ácido de Lewis quiral.
Las cargas bajas del catalizador (0.5-3 mol%) fueron efectivas, produciendo endoductos en buenos rendimientos.
Se lograron enantioselectividades excepcionales, hasta >99% ee.
El procedimiento exhibió un amplio alcance estructural tanto para la azometina como para los componentes dipolarófilos.
El estudio demostró con éxito la primera cicloadición asimétrica catalítica con azometinas derivadas de la ketimina.

Conclusiones:

El sistema de catalizador Cu(I) -Fesulfos es un ácido de Lewis quiral altamente eficaz para las cicloadiciones asimétricas 1,3-dipolares.
Esta metodología proporciona una poderosa herramienta para la síntesis enantioselectiva de moléculas quirales complejas.
La utilidad demostrada con las azometinas derivadas de la ketimina expande la aplicabilidad de las cicloadiciones asimétricas catalíticas.

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