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Las adiciones cíclicas de formales [3 + 2] diastereo y enantioselectivas catalizadas con paladio de

Barry M Trost¹, Patrick J Morris, Simon J Sprague

¹Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA. bmtrost@stanford.edu

Journal of the American Chemical Society

|October 4, 2012

Resumen

Este estudio introduce una reacción de cicloadición catalizada por el paladio que forma ciclopentanos altamente sustituidos a partir de vinilciclopropanos y olefinas. El método logra una alta estereoselectividad a través de un nuevo mecanismo que involucra la estereoinducción remota.

Área de la Ciencia:

Química orgánica es la química orgánica.
La catálisis de la catálisis.
Síntesis asimétrica de síntesis.

Sus antecedentes:

Las reacciones de cicloadición son fundamentales en la síntesis orgánica para la construcción de moléculas cíclicas.
La catálisis con paladio ofrece vías versátiles para la formación de enlaces C-C con alta selectividad.
El desarrollo de métodos enantioselectivos para la síntesis de moléculas complejas sigue siendo un desafío clave.

Objetivo del estudio:

Para desarrollar una nueva reacción de cícloadición formal [3 + 2] catalizada por paladio.
Para sintetizar productos de ciclopentano altamente sustituidos con alto estereocontrol.
Para investigar el mecanismo de la estereoinducción remota en la catálisis del paladio.

Principales métodos:

Utilizando vinilciclopropanos sustituidos y olefinas con déficit de electrones (azlactonas, derivados ácidos de Meldrum).
Empleando la catálisis del paladio con ligandos cuidadosamente diseñados para la estereoselección.
Modulación de las propiedades electrónicas de los reactivos para optimizar los resultados estereoquímicos.

Principales resultados:

Se logró una adición formal [3 + 2]-ciclo diastereoselectiva y enantioselectiva.
Productos de ciclopentano altamente sustituidos sintetizados con excelente estereoselectividad.
Se demostraron altos niveles de estereoinducción remota, distal al bolsillo quiral del catalizador.

Conclusiones:

El método desarrollado proporciona un acceso eficiente a los ciclopentanos estereoquímicamente ricos.
Se propone un nuevo mecanismo que involucra el principio de Curtin-Hammett para explicar la estereoinducción remota observada.
Este trabajo amplía el alcance de las cicloadiciones catalizadas por paladio y la síntesis asimétrica.

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