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Ciclopropanación organofotocatalítica intermolecular de las olefinas no activadas

David M Fischer¹, Henry Lindner¹, Willi M Amberg¹

¹Laboratory of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zurich, Switzerland.

Journal of the American Chemical Society

|January 6, 2023

Resumen

Este estudio introduce un método de organofotocatálisis para crear ciclopropanos altamente sustituidos a partir de olefinas y bromoésteres. La reacción eficiente trabaja con diversos grupos funcionales en condiciones suaves, ofreciendo una nueva ruta sintética.

Área de la Ciencia:

Química orgánica
Fotocatálisis
Metodología sintética

Sus antecedentes:

Los ciclopropanos son motivos estructurales valiosos en productos farmacéuticos y materiales.
La síntesis eficiente y selectiva de ciclopropanos altamente sustituidos sigue siendo un desafío.
La organofotocatálisis ofrece un enfoque sostenible y suave para las transformaciones orgánicas complejas.

Objetivo del estudio:

Desarrollar una nueva reacción de ciclopropanación intermolecular mediante organofotocatálisis.
Para sintetizar ciclopropanos altamente sustituidos a partir de materiales de partida fácilmente disponibles.
Explorar el alcance y las limitaciones de la metodología desarrollada.

Principales métodos:

Ciclopropanación intermolecular de las olefinas con α-bromo-β-cetoésteres y α-bromalonatos.
Utilizando un derivado de la benzothiazinoquinoxalina como organocatalisador.
El uso de la radiación de luz visible en condiciones de reacción suaves.

Principales resultados:

La reacción produjo con éxito ciclopropanos altamente sustituidos con una amplia tolerancia de grupo funcional.
Los sustratos incluían olefinas mono, di y trisubstituidas y varios grupos funcionales como ácidos, alcoholes y ésteres.
La transformación se llevó a cabo de manera eficiente con una carga de catalizador baja (0,5 mol%) en condiciones aeróbicas y acuosas.

Conclusiones:

Se ha establecido un nuevo y eficiente método organofotocatalítico para la ciclopropanación.
La reacción proporciona acceso a diversos y altamente sustituidos ciclopropanos.
Los estudios mecanicistas apoyan un ciclo catalítico propuesto, destacando el potencial de este enfoque para la síntesis de moléculas complejas.

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