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Intercambio de litio-sulfóxido-litio para la síntesis asimétrica de atropisómeros bajo control termodinámico
Jonathan Clayden1, David Mitjans, Latifa H Youssef
1Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK. j.p.clayden@man.ac.uk
Journal of the American Chemical Society
|May 9, 2002
Resumen
Este estudio introduce un nuevo método de resolución dinámica para crear amidas aromáticas enantioméricamente puras. El proceso utiliza un grupo sulfóxido para controlar la conformación, lo que permite una síntesis eficiente de valiosos compuestos atropisoméricos.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La estereoquímica es la estereoquímica.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- Las amidas aromáticas poseen un eje Ar-CO estereogénico.
- El control del atropisomerismo en las amidas aromáticas es un desafío.
- Los métodos existentes carecen de eficiencia y enantioselectividad.
Objetivo del estudio:
- Desarrollar un nuevo método para la resolución dinámica de amidas aromáticas.
- Para sintetizar amidas aromáticas terciarias atropisoméricas altamente enriquecidas enantioméricamente.
- Para introducir un poderoso sesgo conformacional utilizando un sustituto de sulfóxido.
Principales métodos:
- Ortolitización de las amidas aromáticas.
- Reacción con (-) -mentil p-toluenesulfinato para introducir un sulfóxido.
- Intercambio sulfóxido-litio utilizando el t-BuLi.
- El atrapamiento electrófilo del organolitio regenerado.
Principales resultados:
- El sustituto sulfóxido induce un fuerte sesgo conformacional.
- El rápido equilibrio conduce a un único poblado diastereoisomérico atropisómero Ar-CO.
- Las amidas ortolitizadas enantioméricamente puras y conformacionalmente estables son regeneradas.
- El atrapamiento electrófilo produce amidas atropisoméricas altamente enriquecidas enantioméricamente.
Conclusiones:
- El método descrito logra una resolución dinámica bajo control termodinámico.
- Esta estrategia proporciona un acceso eficiente a las amidas aromáticas terciarias atropisoméricas enantioméricamente puras.
- La sustitución temporal de litio por sulfóxido y de nuevo por litio es clave para el proceso.
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