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Adiciones cíclicas asimétricas [4+2] / celetrópicas retro- [4+1] de dióxidos de tiofeno S, S con indolos sustituidos

Shi-Xiong Feng¹, Qi-Tao Lu¹, Yang Lu¹

¹Department of Chemistry, Fudan University, 220 Handan Rd, Shanghai, 200433, China.

Angewandte Chemie (International ed. in English)

|September 2, 2025

Resumen

Este estudio introduce un nuevo método catalítico asimétrico para la síntesis de carbociclos utilizando tiofeno S, S-dióxidos e indolos. La nueva reacción catalizada por el hierro crea hexahidrocarbazoles valiosos con alta enantioselectividad.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

Las cicloadiciones Diels-Alder / celetrópicas retro- [4 + 1 ] de los dióxidos de tiofeno S, S son clave para sintetizar carbociclos insaturados de seis miembros.
Las variaciones asimétricas catalíticas de estas reacciones no se habían logrado anteriormente.

Objetivo del estudio:

Desarrollar el primer método asimétrico catalítico para la retro-[4+1] cicloadición de Diels-Alder y celetrópico de los dióxidos de tiofeno S,S.
Para sintetizar hexahidrocarbazoles enantioméricamente enriquecidos, que son motivos estructurales importantes en los alcaloides indólicos.

Principales métodos:

Utilizó un complejo Fe (III) -bis (oxazolina) como catalizador quiral.
Se emplean dióxidos de tiofeno S,S con grupos funcionales específicos (N-aciloxazolidinona y haluro) para permitir la reacción y controlar la estereoquímica.
Investigó el mecanismo de reacción utilizando estudios computacionales.

Principales resultados:

Se ha logrado una extrusión catalitica asimétrica inversa de demanda de electrones [4+2] de cícloadición/queletrópico retro- [4+1] de SO2 entre los dióxidos de tiofeno S, S y los indoles 3-sustituidos.
Sintetizó una amplia gama de hexahidrocarbazoles con un centro estereogénico cuaternario en buenos rendimientos y altas enantioselectividades.
Se ha demostrado la utilidad sintética a través de transformaciones de productos y una síntesis total de (+) geissoschizoline.

Conclusiones:

Se ha establecido un método nuevo y eficiente para la síntesis enantioselectiva de hexahidrocarbazoles complejos.
La metodología desarrollada proporciona acceso a bloques de construcción quirales valiosos para la síntesis de alcaloides.
La reacción procede a través de un mecanismo escalonado, impulsado por la retro-[4+1] cicloadición.

Palabras clave:

Cheletrópico retro- [4+1] cicloadición Deseromatización Alcalóides del indole Reacción inversa de la demanda de electrones Diels-Alder Dióxidos de tiofeno S,S

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