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Estudio de los Intermedios en la Sustitución Alilica Enantioselectiva Catalizada por el Iridio, la Fosforamidita y la

Simon L Rössler¹, Simon Krautwald¹, Erick M Carreira¹

¹Eidgenössische Technische Hochschule Zürich , Vladimir-Prelog-Weg 3, HCI H335, 8093 Zürich, Switzerland.

Journal of the American Chemical Society

|March 8, 2017

Resumen

Este estudio detalla la sustitución alilica enantioselectiva catalizada por iridio utilizando nuevos ligandos. Los conocimientos mecanicistas revelan intermedios clave y una vía de unión de oxígeno que contribuye a la estabilidad del catalizador.

Área de la Ciencia:

Química organometálica
Catálisis asimétrica
Química orgánica sintética

Sus antecedentes:

Las reacciones de sustitución alilica son fundamentales en la síntesis orgánica.
El desarrollo de métodos enantioselectivos es crucial para acceder a las moléculas quirales.
La catálisis de iridio ofrece una reactividad única para transformaciones desafiantes.

Objetivo del estudio:

Elucidar el mecanismo de la sustitución alilica enantioselectiva catalizada por iridio.
Investigar el papel de los ligandos (fosforamidita, olefina) en esta transformación.
Comprender los factores que contribuyen a la tolerancia al aire del catalizador.

Principales métodos:

Síntesis y caracterización de complejos de iridio clave mediante espectroscopia de RMN y cristalografía de rayos X.
Estudios cinéticos para evaluar la capacidad catalítica de los productos intermedios propuestos.
Investigación del comportamiento del catalizador en presencia de oxígeno molecular.

Principales resultados:

Aislamiento y determinación estructural de los complejos de (η2-alcohol alílico) iridio (I) y (η3-allil) iridio (III).
Demostrar que estos complejos son intermedios relevantes desde el punto de vista catalítico y cinético.
Identificación de una vía de unión al oxígeno reversible que mejore la tolerancia al aire del catalizador.

Conclusiones:

Los complejos de iridio reportados son intermedios clave en la sustitución alilica enantioselectiva.
El sistema de ligando (fosforamidita, olefina) facilita una alta enantioselectividad.
La unión reversible de oxígeno confiere una tolerancia significativa al aire al sistema catalítico.

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