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Obtención de energía catalítica de la separación de cargas: asistencia estereoelectrónica y zwitteriónica en la

Gabriel Dos Passos Gomes¹, Igor V Alabugin¹

¹Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306-439, United States.

Journal of the American Chemical Society

|February 11, 2017

Resumen

Los catalizadores de oro aceleran dramáticamente la ciclización de Bergman (BC) al permitir un mecanismo cooperativo único. Este proceso transforma una reacción típicamente desfavorable en un intermedio estable, abriendo nuevas vías en la síntesis química.

Área de la Ciencia:

Química orgánica
Catálisis
Mecanismos de reacción

Sus antecedentes:

Las reacciones pericíclicas implican la formación y ruptura de enlaces concertados.
Las reacciones de cicloaromatización, como la ciclización de Bergman (BC), difieren mecánicamente, sacrificando enlaces para formar un solo enlace y deteniéndose en un intermedio diradical.

Objetivo del estudio:

Para dilucidar el mecanismo catalítico de Gold (I) en la ciclización de Bergman.
Comprender cómo el oro (I) logra una aceleración significativa de la velocidad y altera la vía de reacción.

Principales métodos:

Análisis computacional de los mecanismos de reacción.
Análisis de distorsión e interacción para cuantificar las interacciones entre catalizador y sustrato.
Investigación de los efectos estereoelectrónicos y las capacidades de estabilización de carga del catalizador Gold.

Principales resultados:

Los catalizadores de oro (I) aceleran el BC a través de "LUMO umpolung" y un cruce de mecanismo diradical a zwitteriónico.
Esta cooperatividad da como resultado un aumento de las tasas de más de cien mil millones de veces.
La reacción se convierte en un cambio sigmatrópico "abortado", estabilizando el estado de transición.

Conclusiones:

La catálisis del oro transforma la ciclificación de Bergman en un proceso cooperativo único.
El intermedio estabilizado facilita la captura y permite una nueva reactividad de los sistemas poliinsaturados.
Las interacciones catalizador-sustrato se mejoran significativamente en el estado de transición.

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