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Síntesis de macrociclos a través de adiciones de ciclo [2 + 2 + 2] mediadas por cobalto
Llorente V R Boñaga1, Han-Cheng Zhang, Alessandro F Moretto
1Drug Discovery, Johnson & Johnson Pharmaceutical, Research & Development, Spring House, Pennsylvania 19477-0776, USA.
Journal of the American Chemical Society
|March 10, 2005
Resumen
Este estudio detalla la formación del macrociclo catalizado por cobalto a partir de alfa, omega y diines. Las mejores condiciones permiten una síntesis eficiente de macrociclos que contienen piridina, ofreciendo un enfoque flexible para los químicos orgánicos.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis es la catálisis.
- Ciencias Macromoleculares Ciencias Macromoleculares
Sus antecedentes:
- Los compuestos macrocíclicos son cruciales en varios campos científicos.
- La síntesis eficiente de macrociclos complejos sigue siendo un desafío.
- La ciclotrimerización mediada por cobalto ofrece un camino hacia nuevas estructuras macrocíclicas.
Objetivo del estudio:
- Investigar la formación de macrociclos a partir de alfa, omega y diinas mediante la cociclotrimerización mediada por cobalto.
- Desarrollar mejores condiciones de reacción para sintetizar macrociclos que contienen piridina.
- Explorar la regioselectividad y el alcance de estas reacciones de cicloadición.
Principales métodos:
- Cobalto catalizado [2+2+2] cicloadición de alfa, omega-diinas con nitriles, cianamidas o isocyanatos.
- Utilizado CpCo(CO) 2 (Cp = ciclopentadienida) como el catalizador.
- Parámetros de reacción optimizados incluyendo temperatura, disolvente y tiempo de reacción.
Principales resultados:
- Con éxito sintetizó macrociclos que contienen piridina, incluidos meta- y para-piridinófanos.
- Se ha demostrado la regioselectividad influenciada por la longitud del linker y los factores estereoelectrónicos.
- Se lograron altos rendimientos y mejores condiciones de reacción, por ejemplo, rendimiento del 87% para diyne 6 con p-tolunitrile a 100°C.
- Demostró una síntesis eficiente de piridinofanos macrocíclicos utilizando isocyanatos, por ejemplo, un rendimiento del 64% para 44p.
- Se informó de una variante macrocíclica de la reacción de Vollhardt co-ciclotrimerizando diinas con alquinas.
Conclusiones:
- Desarrolló un conveniente y flexible protocolo sintético para compuestos de piridina macrocíclicos.
- La cicloadición [2+2+2] mediada por cobalto mejorada es una herramienta poderosa para la síntesis de macrociclos.
- La regioselectividad puede ser controlada por el diseño del sustrato y las condiciones de reacción.
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