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Origen de la formación selectiva de furanos 5-vinil-2-metileno a partir de adiciones cíclicas de oxalilo y dieno

Yike Zou¹, Shuming Chen¹, K N Houk¹

¹Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095-1569 , United States.

Journal of the American Chemical Society

|July 23, 2019

Resumen

Este estudio revela que las cicloadiciones de paladio-oxalilo (Pd-oxalilo) deficientes en electrones con dienos conjugados se producen mediante un mecanismo escalonado. El análisis computacional destaca el papel de los sustituyentes de éster en la facilitación de la formación de enlaces C-C.

Área de la Ciencia:

Química organometálica
Síntesis orgánica
Química computacional

Sus antecedentes:

Las cicloadiciones catalizadas por el paladio son cruciales en la síntesis orgánica.
Comprender los mecanismos de reacción es clave para optimizar las rutas sintéticas.

Objetivo del estudio:

Investigar el mecanismo de las cicloadiciones (3+2) entre los Pd-oxalilos deficientes en electrones y los dienos conjugados.
Aclarar los factores que influyen en la reactividad y la selectividad.

Principales métodos:

Se emplearon cálculos de la teoría funcional de la densidad (DFT).
Análisis de las vías de reacción, estados de transición y propiedades electrónicas.

Principales resultados:

Se apoya computacionalmente un mecanismo escalonado con formación inicial de enlaces C-C.
Los sustituyentes de éster que retiran electrones reducen la energía LUMO y reducen las barreras de inserción migratoria.
Las reacciones de monoeno son desfavorables debido a las mayores barreras de inserción y las barreras de eliminación de CO.
Los dienos conjugados facilitan la formación de especies electrófilas η3 Pd-alilo y la formación de enlaces C-O.

Conclusiones:

El estudio proporciona información mecanicista detallada sobre las cicloadiciones de Pd-oxalilo.
Los sustituyentes de éster y la conjugación de dieno son críticos para las reacciones de cicloadición eficientes.
Los cálculos de DFT son valiosos para predecir y comprender la reactividad en la catálisis organometálica.

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