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Catálisis directa por ácido de Lewis excitado por la luz visible de adiciones fotociclógicas intermoleculares [2+2]

Xiaoqiang Huang¹, Taylor R Quinn², Klaus Harms¹

¹Fachbereich Chemie, Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35043 Marburg, Germany.

Journal of the American Chemical Society

|June 24, 2017

Resumen

Este estudio introduce una nueva reacción activada por luz visible utilizando un catalizador quiral de rodio para cicloadiciones [2+2] estereocontroladas. El método produce eficientemente ciclobutanos, incluidos los estereocentros cuaternarios complejos.

Área de la Ciencia:

Química orgánica
Fotocatálisis
Síntesis asimétrica

Sus antecedentes:

La catálisis del ácido quiral de Lewis es crucial para la síntesis estereoselectiva.
La fotocatálisis con luz visible ofrece condiciones de reacción sostenibles y suaves.
El desarrollo de métodos para la construcción de estereocentros cuaternarios sigue siendo un desafío importante.

Objetivo del estudio:

Para reportar un nuevo diseño de reacción utilizando luz visible y un ácido de Lewis quiral.
Para obtener cicloadiciones intermoleculares [2+2] altamente estereocontroladas.
Para sintetizar ciclobutanos con estereocentros cuaternarios de todo el carbono.

Principales métodos:

Utilizando un complejo quiral de rodio unido al sustrato como catalizador de ácido de Lewis.
Utilizando la luz visible para generar un estado excitado del catalizador.
Realización de cicloadiciones intermoleculares [2+2] con varios cosubstratos.

Principales resultados:

La reacción se lleva a cabo de una manera altamente estereocontrolada, produciendo ciclobutanos.
Se obtiene una enantioselectividad excelente (hasta >99% ee) y una diastereoselectividad (hasta >20:1 d.r. En el caso de los
Demostró la capacidad de formar estereocentros cuaternarios de todo el carbono, incluidas las estructuras espirocíclicas, intermolecularmente.

Conclusiones:

El método desarrollado proporciona una ruta eficiente a los derivados complejos del ciclobutano.
La activación con luz visible de los ácidos quirales de Lewis permite nuevas transformaciones asimétricas.
Este enfoque amplía el conjunto de herramientas para la construcción de centros estereogénicos desafiantes.

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