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Hidrohidrazinación intramolecular catalizada por platino: evidencia para la inserción de alqueno en un enlace Pt-N
Jessica M Hoover1, Antonio Dipasquale, James M Mayer
1Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, USA.
Journal of the American Chemical Society
|March 26, 2010
Resumen
Los complejos dicationicos de platino ((II) catalizan la hidrohidrazinación de alqueno, formando eficientemente las N-amino lactamas. Este descubrimiento ofrece una nueva ruta sintética para valiosos compuestos heterocíclicos.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Síntesis orgánica La síntesis orgánica.
- La catálisis de la catálisis.
Sus antecedentes:
- La hidrohidrazinación intramolecular de alquenos es una transformación clave para la síntesis de heterociclos que contienen nitrógeno.
- El desarrollo de sistemas catalíticos eficientes y selectivos para esta reacción sigue siendo un objetivo importante en la química orgánica.
Objetivo del estudio:
- Investigar el potencial de los complejos dicationic (bpy) Pt (II) como catalizadores para la hidrohidrazinación intramolecular de alquenos.
- Para optimizar las condiciones de reacción y dilucidar el mecanismo catalítico.
Principales métodos:
- Cribado de catalizadores de platino (II), incluido el Pt (bpy) Cl (II) con trifluorometanosulfonato de plata (AgOTf).
- Optimización de los parámetros de reacción como la temperatura, la carga del catalizador y el disolvente (DMF-d7).
- Caracterización de intermediarios catalíticos y estudios mecanicistas que involucran la activación de N-H y la inserción de alquenos.
Principales resultados:
- Pt(bpy) Cl(2) (10 mol %) y AgOTf (20 mol %) catalizan efectivamente la conversión de hidrazidos sustituidos a lactamos N-amino de cinco y seis miembros.
- La reacción produce exclusivamente el producto de exociclización 5, lo que demuestra una alta regioselectividad.
- Se identificaron estados de reposo catalíticamente competentes, un complejo Pt-amidato y un complejo Pt-alquilo.
Conclusiones:
- Los complejos dicationicos Pt (II) son catalizadores eficientes para la hidrohidrazinación intramolecular de los alquenos.
- El ciclo catalítico implica la activación de N-H, la inserción de alqueno en el enlace Pt-N y la regeneración del catalizador Pt-amidato.
- Esta metodología proporciona una ruta novedosa y selectiva a los N-amino lactams.
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