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Procesos de intercambio en los marcos de BINOLATO de metales alcalinos de tierras raras de Shibasaki y su relevancia

Jerome R Robinson¹, Jun Gu¹, Patrick J Carroll¹

¹P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.

Journal of the American Chemical Society

|May 14, 2015

Resumen

Los catalizadores de metal alcalino de tierras raras BINOLATO (REMB) muestran una alta enantioselectividad. Nuevos estudios revelan que la desprotonación del sustrato es clave para la selectividad en la catálisis ácido-Lewis/base-Brønsted, desafiando modelos anteriores.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
Catalización asimétrica por catálisis asimétrica.

Sus antecedentes:

Los catalizadores de metales alcalinos de tierras raras BINOLATO (REMB) son altamente efectivos para la síntesis enantioselectiva.
Persisten cuestiones fundamentales con respecto a su reactividad y especies activas.

Objetivo del estudio:

Investigar la identidad de los catalizadores activos en las reacciones ácido de Lewis (LA) y ácido de Lewis/base de Brønsted (LA/BB).
Para dilucidar el mecanismo de la catálisis REMB utilizando estudios combinados de espectroscopia y reactividad.

Principales métodos:

Utilizó espectroscopia de intercambio para determinar las tasas de autointercambio de ligando y metal alcalino en marcos de RE/Li.
Se aisló y caracterizó el primer complejo REMB con un sustrato unido para estudios de reactividad.

Principales resultados:

Demostró la utilidad de la espectroscopia de intercambio para sondear la dinámica de la solución del catalizador REMB.
Se observó que la desprotonación del sustrato por el marco del catalizador es esencial para lograr la selectividad.
Los datos espectroscópicos contradicen las propuestas mecanicistas anteriores que se centraban únicamente en las especies tris ((BINOLATE).

Conclusiones:

Comprensión ampliada de la estructura y reactividad del catalizador REMB.
Identificó la desprotonación del sustrato como un paso crítico en la catálisis LA/BB.
Abrió nuevas vías para el diseño de catalizadores REMB avanzados.

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