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Los carbenos de cobre discretos de puente y terminales en ciclopropanación catalizada por cobre
Xuliang Dai1, Timothy H Warren
1Department of Chemistry, Georgetown University, Washington, DC. 20057, USA.
Journal of the American Chemical Society
|August 12, 2004
Resumen
Los complejos de cobre (I) beta-diketiminato catalizan las reacciones de ciclopropanación. Se aisló y caracterizó un intermediario de carbeno de dicobre, que muestra una disociación reversible a un carbeno de cobre terminal, que eficientemente ciclopropana el estireno.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Química de los carbenos La química de los carbenos
Sus antecedentes:
- Los complejos de cobre (I) con ligandos de beta-diketiminato son catalizadores efectivos.
- Las reacciones de transferencia de carbenos son cruciales en la síntesis orgánica.
Objetivo del estudio:
- Para investigar la actividad catalítica de los complejos de cobre (I) beta-diketiminato en la ciclopropanación.
- Para sintetizar y caracterizar nuevas especies de dicobre y carbenos terminales de cobre.
Principales métodos:
- La catálisis con el cobre (I) complejos de beta-diketiminato.
- Aislamiento y caracterización estructural de los carbenos de dicobre.
- Estudios cinéticos de las reacciones de carbenos.
- Cálculos de la Teoría Funcional de la Densidad (DFT).
Principales resultados:
- El complejo de cobre (I) [Me2NN]Cu (eta2-etileno) cataliza la ciclopropanación del estireno.
- Se aisló y caracterizó estructuralmente un carbeno dicopro, [[Me2NN]Cu]2(mu-CPh2).
- Este carbeno de dicobre se disocia de manera reversible a un carbeno de cobre terminal, [Me2NN]Cu=CPh2.2.
- El carbeno de cobre terminal eficientemente ciclopropana el estireno y se descompone en tetrafeniletileno.
- Los estudios de DFT sugieren una mayor unión de Cu-C pi hacia atrás en los carbenos de dicobre.
Conclusiones:
- Los carbenos intermedios de dicobre juegan un papel en la ciclopropanación catalizada por el cobre.
- Los carbenos terminales de cobre son especies aislables y reactivas.
- El diseño de los ligandos influye en la estabilidad y la reactividad de los complejos de carbenos de cobre.
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