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Catálisis cooperativa de la base chiral de Lewis para la ciclización enantioselectiva a través de la activación de
Takumaru Kurihara1, Masahiro Kojima1, Tatsuhiko Yoshino1,2
1Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
Journal of the American Chemical Society
|April 11, 2022
Resumen
Un nuevo sistema catalítico cooperativo permite la activación enantioselectiva de C-H para la síntesis de benzolactamas. Este método utiliza un complejo de rodio y una base quiral de Lewis, logrando altos rendimientos y una excelente enantioselectividad.
Área de la Ciencia:
- Química orgánica
- Catálisis
- Metodología sintética
Sus antecedentes:
- La activación de C-H es una estrategia crucial en la síntesis orgánica.
- El desarrollo de métodos enantioselectivos para la funcionalización de C-H sigue siendo un desafío importante.
- La catálisis cooperativa ofrece un enfoque prometedor para mejorar la reactividad y la selectividad.
Objetivo del estudio:
- Desarrollar una ciclización enantioselectiva [4+3] a través de la activación C(sp2)-H.
- Establecer un sistema catalítico cooperativo utilizando un complejo Cp*Rh{III} y una base quiral de Lewis.
- Para sintetizar diversos benzolactamas con una alta enantioselectividad.
Principales métodos:
- Utilizando un sistema catalítico cooperativo compuesto por un complejo Cp*Rh (III) y un catalizador quiral de isocalcogenurea.
- Generando un intermediario de acilo amonio α,β insaturado.
- Reaccionando el intermedio con un ciclo metálico formado por el catalizador de rodio y un derivado de benzilamina.
Principales resultados:
- Ciclización [4+3] enantioselectiva exitosa a través de la activación C(sp2)-H.
- Síntesis de varios benzolactamos en buenos rendimientos.
- Se obtiene una enantioselectividad excelente, de hasta 99:1.
Conclusiones:
- El sistema catalítico cooperativo controla efectivamente la enantioselectividad en las funcionalizaciones C-H catalizadas por metales de transición.
- La catálisis de bases quiral de Lewis es una herramienta poderosa para la síntesis asimétrica.
- Esta metodología proporciona un acceso eficiente a los benzolactamas enriquecidos enantioméricamente.
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