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Aminocarbonización regioselectiva Pd catalizada de estirenos con aminofenoles altamente controlados por ligandos

Tongyu Xu¹, Feng Sha¹, Howard Alper¹

¹Centre for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa , 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.

Journal of the American Chemical Society

|May 10, 2016

Resumen

Este estudio demuestra la carbonilación de estirenos controlada por ligando y catalizada por paladio, logrando una alta quimioselectividad y regioselectividad para la síntesis de amidas. La elección del ligando dicta la formación de amida lineal versus ramificada, ofreciendo un control preciso en la síntesis orgánica.

Área de la Ciencia:

Síntesis orgánica
Catálisis
Química medicinal

Sus antecedentes:

La quimioselectividad y la regioselectividad simultáneas en la síntesis orgánica presentan un desafío significativo.
La catálisis de metales de transición ofrece una estrategia viable para controlar la selectividad a través de efectos de ligando.

Objetivo del estudio:

Para lograr la carbonilación regioselectiva controlada por ligando catalizada por el paladio de estirenos con aminofenoles.
Para sintetizar selectivamente amidas lineales y ramificadas con altos rendimientos y selectividad.

Principales métodos:

Utilizó reacciones de carbonilación catalizadas por el paladio.
Se utilizan ligandos específicos, el tris ((4-metoxifenil) fosfina (L3) y el 1,3,5,7-tetrametil-2,4,8-trioxa-6-fenil-6-fosfadamantano (L5).
Investigó el papel de aditivos como el ácido borónico y el ácido 5-clorosalicílico, y los disolventes (acetonitrilo, butanona).

Principales resultados:

Se ha conseguido la formación quimioselectiva de amidas a partir de estirenos y aminofenoles.
Se obtuvieron amidas lineales con L3 en acetonitrilo, mientras que se obtuvieron amidas ramificadas con L5 en butanona, ambas con altos rendimientos y selectividad.
Propiedades correlacionadas del ligando (ángulo del cono, parámetro electrónico de Tolman) con reactividad y regioselectividad.
Se ha demostrado la influencia de los aditivos ácidos como fuentes de protones y contraiones en la reactividad y la selectividad.

Conclusiones:

La naturaleza del ligando es el factor crítico que determina la regioselectividad en esta carbonilación catalizada por el paladio.
Este trabajo proporciona un método para controlar la estructura de la amida a través de la selección de ligandos en la catálisis del paladio.
Comprender los efectos de los ligandos y las funciones de los aditivos mejora la precisión de la síntesis orgánica.

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