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Estudio mecanicista de la hidroaminación intermolecular catalizada por el oro de los alenos
Z Jane Wang1, Diego Benitez, Ekaterina Tkatchouk
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Journal of the American Chemical Society
|August 27, 2010
Resumen
La catálisis del oro permite una eficiente hidroaminación intermolecular de alenos con hidrazidas. Los estudios mecánicos revelan un catalizador de oro y un mecanismo de esfera externa, con ligandos deficientes en electrones acelerando la reacción.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Síntesis orgánica La síntesis orgánica.
Sus antecedentes:
- La hidroaminación intermolecular de los alenos es una transformación sintética valiosa.
- La catálisis del oro ofrece una reactividad única para la formación de enlaces C-H y C-N.
- La comprensión de los mecanismos de reacción es crucial para la optimización del catalizador.
Objetivo del estudio:
- Para dilucidar el mecanismo de la hidroaminación intermolecular de alenos utilizando nucleófilos de hidrazida catalizados por un complejo de oro.
- Para identificar las especies de catalizadores de oro activos y determinar los parámetros cinéticos.
- Para investigar la influencia de la electrónica de ligandos en la actividad catalítica.
Principales métodos:
- Estudios mecanicistas detallados que incluyen experimentos cinéticos.
- Investigación del estado de reposo del catalizador y órdenes de reacción.
- Estudios computacionales para apoyar los mecanismos propuestos.
- Varios ligandos de fosfina en el catalizador de oro.
Principales resultados:
- La reacción continúa fácilmente con 3-12% de Ph ((3) PAuNTf ((2) y nucleófilos de hidrazida.
- La reacción es de primer orden en oro y aleno, y de orden cero en nucleófilo.
- El catalizador activo es el oro monomérico, y el estado de transición que limita la velocidad no involucra al nucleófilo.
- Los estudios computacionales sugieren una esfera externa, un mecanismo de dos pasos sin intermediarios.
- Más ligandos de fosfina deficientes en electrones aceleran la reacción.
Conclusiones:
- La hidroaminación catalizada por el oro de alenos con hidrazidos sigue un mecanismo de esfera externa.
- La actividad del catalizador está modulada por la electrónica del ligando, con ligandos con déficit de electrones que mejoran el rendimiento.
- Este estudio proporciona conocimientos mecánicos clave para el desarrollo de catalizadores de oro mejorados para reacciones de hidroaminación.
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