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Los derivados de quiral squaramide son excelentes catalizadores donantes de enlaces de hidrógeno

Jeremiah P Malerich¹, Koji Hagihara, Viresh H Rawal

¹Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA.

Journal of the American Chemical Society

|October 14, 2008

Resumen

Las cuadramidas quirales son una nueva clase de catalizadores donantes de enlaces de hidrógeno, que ofrecen una alternativa más simple a las tioureas. Estos catalizadores promueven eficientemente las reacciones de adición conjugada con altos rendimientos y enantioselectividades.

Área de la Ciencia:

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

Sus antecedentes:

Las tioureas son catalizadores asimétricos establecidos para reacciones promovidas por enlaces de hidrógeno.
Numerosas publicaciones documentan el éxito de la tiourea quiral en diversas transformaciones químicas.

Objetivo del estudio:

Introducir las squaramidas como un nuevo y eficaz andamio para los catalizadores donantes de enlaces quirales de hidrógeno.
Para demostrar la utilidad de los catalizadores de squaramide en la catálisis asimétrica.

Principales métodos:

Síntesis de un catalizador de squaramida modificado por (-) -cinconina a través de un proceso de dos pasos a partir del cuadrato de metilo.
Aplicación del catalizador de la squaramida en la adición conjugada de compuestos 1,3-dicarbonilo a los beta-nitrostirenos.

Principales resultados:

El catalizador de squaramida fue efectivo a bajas cargas (0,1 mol%).
Los productos de adición conjugada se obtuvieron en altos rendimientos.
Se lograron excelentes enantioselectividades en las reacciones catalizadas.

Conclusiones:

Las squaramidas representan un andamio altamente efectivo y más simple para los catalizadores donantes de enlaces quirales de hidrógeno en comparación con las tioureas.
El catalizador de squaramide desarrollado muestra una promesa significativa para las reacciones de adición conjugada asimétrica.

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