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Un efecto de activación de boro permite la hidrogenación asimétrica catalizada por cobalto de alquenos estéricamente
Peter Viereck1, Simon Krautwald1, Tyler P Pabst1
1Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States.
Journal of the American Chemical Society
|February 4, 2020
Resumen
Se logró una hidrogenación altamente enantioselectiva de alquenos 1,1-diborilo asimétricos utilizando catalizadores de cobalto. Esto genera valiosos bloques de construcción de diborilalcanos enriquecidos con enantio para su posterior síntesis.
Área de la Ciencia:
- Química organometálica
- Catálisis
- Síntesis orgánica
Sus antecedentes:
- Los alquenos 1,1-diborilo son productos intermedios sintéticos muy versátiles.
- El desarrollo de métodos enantioselectivos para su transformación es crucial para acceder a las moléculas quirales.
Objetivo del estudio:
- Desarrollar un sistema catalítico para la hidrogenación enantioselectiva de alquenos 1,1-diborilo no simétricos.
- Investigar la influencia de los sustituyentes de boro en la actividad catalítica y la selectividad.
Principales métodos:
- Hidrogenación de alquenos 1,1-diborilo no simétricos mediante el uso de complejos de cobalto C1-simétricos de piridina.
- Estudio sistemático de los efectos del sustituto.
- Estudios de etiquetado con deuterio para elucidar los mecanismos de reacción.
Principales resultados:
- Se obtuvieron altos rendimientos y enantioselectividades para una gama de alquenos 1,1-diborilo.
- Se encontró que los boronatos estériles sin carga (-BDan, -BCat, -Beg) promueven la hidrogenación a través de vías de inserción irreversibles dirigidas al α-boro.
- Los intermediarios quirales con dos sustituyentes de boro diferentes fueron identificados a través de estudios de etiquetado con deuterio.
Conclusiones:
- Los complejos de cobalto PDI C1-simétricos son catalizadores eficaces para la hidrogenación enantioselectiva de los alquenos 1,1-diborilo no simétricos.
- La naturaleza del sustituto de boro tiene un impacto significativo en la eficiencia y el mecanismo catalítico.
- Este trabajo proporciona acceso a bloques de construcción de diborilalcanos enriquecidos con enantio, valiosos para la síntesis asimétrica.
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