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Control general del catalizador de la monoisomerización de 1-alquenos a trans-2-alquenos

Casey R Larsen¹, Gulin Erdogan, Douglas B Grotjahn

¹Department of Chemistry and Biochemistry, 5500 Campanile Drive, San Diego State University , San Diego, California 92182-1030, United States.

Journal of the American Chemical Society

|January 16, 2014

Resumen

Los investigadores desarrollaron un nuevo sistema catalizador para la isomerización de alquenos, produciendo eficientemente trans-2-alquenos a partir de alquenos terminales. Este avance ofrece un control preciso sobre la posición del doble enlace y la estereoselectividad, evitando el equilibrio termodinámico.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
La catálisis es la catálisis.
Síntesis orgánica La síntesis orgánica.

Sus antecedentes:

Los alquenos terminales son bloques de construcción valiosos en la síntesis orgánica.
La isomerización de alquenos terminales a alquenos internos presenta desafíos en el control de la regioselectividad y la estereoselectividad.
Los sistemas catalíticos existentes a menudo conducen a un equilibrio termodinámico, lo que limita el rendimiento de los isómeros deseados.

Objetivo del estudio:

Desarrollar un sistema catalítico general para la isomerización de alquenos terminales a 2-alquenos internos.
Para lograr un alto control sobre el posicionamiento del enlace doble y la selectividad cis/trans.
Para minimizar el equilibrio termodinámico de los isómeros de alqueno.

Principales métodos:

Se utilizan mezclas de los complejos 1 y 3 de (C5Me5) Ru, con un ligando de fosfina bifuncional.
Se emplean bajas cargas de catalizador (típicamente 1 mol %) de los complejos 1 y 3.
Reacciones realizadas a temperaturas moderadas (40-70 °C).

Principales resultados:

Isomerización exitosa de alquenos terminales a sus 2 isómeros con alta regioselectividad.
Logró una excelente estereoselectividad, formando predominantemente (E)-2-alquenos (isómeros trans).
El sistema catalizador demostró una resistencia superior al equilibrio termodinámico en comparación con los métodos conocidos.

Conclusiones:

Las mezclas de los complejos 1 y 3 de (C5Me5) Ru representan un catalizador altamente efectivo para la isomerización de alqueno.
Este sistema catalítico proporciona una solución general para controlar la posición del doble enlace y la selectividad cis/trans.
La capacidad de evitar el equilibrio termodinámico hace que este método sea valioso para producir isómeros específicos de alquenos.

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