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Reacciones intermoleculares catalizadas por Rh de compuestos cíclicos α-diazocarbonilo con selectividad sobre la
Andrew DeAngelis1, Olga Dmitrenko, Joseph M Fox
1Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
Journal of the American Chemical Society
|June 9, 2012
Resumen
Las nuevas reacciones catalizadas por Rh permiten transformaciones intermoleculares selectivas utilizando compuestos diazocarbonilo cíclicos. Estos métodos superan el obstáculo estérico, lo que facilita la ciclopropanación y las inserciones X-H con diversos sustratos.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis es la catálisis.
Sus antecedentes:
- Las reacciones quimioselectivas son cruciales en la síntesis orgánica.
- Los Rh-carbenoides son intermediarios versátiles, pero a menudo se enfrentan a desafíos con la selectividad sobre vías competidoras como la eliminación del β-hidruro.
Objetivo del estudio:
- Desarrollar nuevas reacciones intermoleculares catalizadas por Rh de compuestos cíclicos α-diazocarbonilo.
- Para lograr la quimioselectividad sobre la eliminación de β-hidruro.
- Explorar el alcance y las limitaciones de estas nuevas transformaciones.
Principales métodos:
- Utilizó compuestos cíclicos α-diazocarbonilo como precursores de los Rh-carbenoides.
- Reacciones intermoleculares investigadas que incluyen ciclopropanación, ciclopropenación e inserciones X-H.
- Calculaciones de la Teoría Funcional de Densidad Empleada (DFT) para apoyar propuestas mecanicistas.
Principales resultados:
- Demostró las primeras reacciones intermoleculares generales de Rh-carbenoides selectivas sobre la migración de enlaces terciarios β-C-H.
- Se han logrado transformaciones exitosas con una amplia gama de sustratos.
- Se identificaron factores estéricos y conformacionales que influyen en la reactividad, particularmente para anillos de siete miembros.
Conclusiones:
- Los compuestos cíclicos α-diazocarbonilo, especialmente los anillos de cinco y seis miembros, facilitan las reacciones intermoleculares catalizadas por Rh al mejorar la conjugación de carbenos.
- La flexibilidad estérica y conformacional de anillos más grandes puede obstaculizar la reactividad intermolecular.
- Los métodos desarrollados ofrecen una nueva y poderosa herramienta para la síntesis orgánica selectiva.
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