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Captura enantioselectiva de 1,5-dipolos que contienen Pd mediante cetenos fotogenerados: acceso a lactonas de 7

Yi Wei¹, Song Liu², Miao-Miao Li¹

¹CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry , Central China Normal University , 152 Luoyu Road , Wuhan 430079 , China.

Journal of the American Chemical Society

|December 13, 2018

Resumen

Este estudio introduce una nueva reacción de cicloadición enantioselectiva [5+2] mediante fotoactivación y catálisis del paladio. El método sintetiza eficientemente las lactonas de 7 miembros con estereocentros cuaternarios quirales.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

El acceso a los estereocentros cuaternarios quirales en las lactonas de 7 miembros es sintéticamente desafiante.
Las reacciones de cicloadición son herramientas poderosas para construir compuestos cíclicos.
La catálisis asimétrica y la catálisis fotorredóxica ofrecen estrategias complementarias para la síntesis de moléculas complejas.

Objetivo del estudio:

Desarrollar una nueva reacción de cicloadición enantioselectiva [5+2].
Para sintetizar lactonas de 7 miembros que llevan estereocentros cuaternarios quirales.
Para combinar la fotoactivación con la catálisis asimétrica de paladio para una síntesis eficiente.

Principales métodos:

Enantioselectiva [5+2] cicloadición entre los carbonatos de viniletileno y las α-diazocetonas.
Utilizando la radiación de luz visible para la fotoactivación.
Empleando catálisis asimétrica de paladio para controlar la estereoquímica.
Generación in situ y captura sin rastro de productos intermedios de ceteno.

Principales resultados:

Desarrollo exitoso de la primera cicloadición enantioselectiva [5+2] de carbonatos de viniletileno y α-diazocetonas.
Síntesis eficiente de diversas lactonas de 7 miembros con un alto rendimiento (hasta el 99%).
Se obtiene una alta enantioselectividad, con relaciones enantioméricas de hasta 96:4 er.
Formación de estereocentros cuaternarios quirales desafiantes.

Conclusiones:

El método desarrollado proporciona una ruta fácil y eficiente a las valiosas lactonas de 7 miembros.
La combinación de fotoactivación y catálisis asimétrica de paladio es eficaz para esta transformación.
Este enfoque ofrece una poderosa estrategia para construir moléculas quirales complejas.

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