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Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators

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Perspectivas sobre el interruptor de estereoselectividad en las ciclizaciones de Mannich en tándem iniciadas por

Liu-Peng Zhao¹, Sheng-Ye Zhang¹, Hua-Kui Liu¹

¹The State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, CAS, University of Chinese Academy of Sciences, 345 Lingling Rd, Shanghai 200032, China.

Journal of the American Chemical Society

|July 4, 2023

Resumen

Un nuevo protocolo de estereoinversión permite la síntesis selectiva de las espiroindolinas tetraciclicas, cruciales para los alcaloides indoles biológicamente activos. Este método facilita el estereocontrol en la síntesis de moléculas complejas, incluida la estricnina.

Área de la Ciencia:

Química orgánica
Química sintética
Química medicinal

Sus antecedentes:

Las espiroindolinas tetraciclicas son estructuras centrales en muchos alcaloides indólicos biológicamente activos.
La síntesis divergente de estos motivos es un desafío debido al limitado control de estereoselectividad.

Objetivo del estudio:

Desarrollar un protocolo de estereoinversión fácil para la construcción de espiroindolinas tetraciclicas.
Para lograr una alta estereoselectividad en el acceso a núcleos diastereoisoméricos de alcaloides indólicos de monoterpenos.

Principales métodos:

Las ciclizaciones en tándem iniciadas por la adición de Michael Mannich.
Estudios mecanicistas que incluyen RMN in situ, experimentos de control y cálculos DFT.
Estrategia de conmutación de estereoselectividad aplicada a los sustratos de enamina y éter vinílico.

Principales resultados:

Se estableció un nuevo protocolo de estereoinversión para las espiroindolinas tetraciclicas.
La reacción se produce a través de un raro reordenamiento retro-Mannich/re-Mannich con escisión del enlace C-C.
Las propiedades electrónicas de los grupos protectores de N y los catalizadores de ácido de Lewis influyen en la estereoinversión.
Síntesis total exitosa en escala de gramos de estricnina y deetilibofillidina.

Conclusiones:

El protocolo desarrollado proporciona un fácil acceso a núcleos de espiroindolina diastereoisoméricos con alta selectividad.
Las ideas mecánicas permiten una estrategia de conmutación de estereoselectividad para la síntesis de diversos alcaloides indólicos.
El método es práctico y aplicable a la síntesis total de productos naturales complejos.

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