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Ciclizaciones oxidativas en un disolvente no polar utilizando oxígeno molecular y estudios sobre la estereoquímica de

Raissa M Trend¹, Yeeman K Ramtohul, Brian M Stoltz

¹The Arnold and Mabel Beckman Laboratories of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, MC 164-30, Pasadena, California 91125, USA.

Journal of the American Chemical Society

|December 15, 2005

Resumen

La catálisis del paládio (II) permite las ciclizaciones oxidativas utilizando el oxígeno molecular como oxidante. Este método funciona eficientemente varios nucleófilos, incluidos los alcoholes y los fenoles, con diversos sustratos de olefinas.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
La catálisis de la catálisis.
Síntesis orgánica La síntesis orgánica.

Sus antecedentes:

Las ciclizaciones oxidativas son cruciales para construir moléculas orgánicas complejas.
La catálisis del paladio ofrece vías versátiles para la formación de enlaces C-H y C-heteroatomo.
El desarrollo de sistemas catalíticos eficientes con oxidantes ambientalmente benignos es un desafío clave.

Objetivo del estudio:

Desarrollar una ciclización oxidativa catalizada por el paladio (II) de nucleófilos heteroatómicos en olefinas no activadas.
Investigar el alcance y las limitaciones de la reacción con varios nucleófilos y sustratos de olefinas.
Para aclarar el mecanismo de reacción, incluyendo los aspectos estereoquímicos y el papel de los ligandos.

Principales métodos:

Ciclización oxidativa catalítica con el uso de sales de paladio (II) y piridina.
Oxígeno molecular como el único oxidante estequiométrico en el tolueno.
Estudios de reactividad con complejos de paladio ligado a N y etiquetado estereospecífico de deuterio.

Principales resultados:

Ciclización exitosa de fenoles, alcoholes primarios, ácidos carboxílicos, ácidos vinílogos y amidas en olefinas no activadas.
Tolerancia demostrada para diversos patrones de sustitución de olefinas y fenoles ricos en electrones.
Formación de sistemas fundidos y espirocíclicos con alcoholes y derivados ácidos.
Los estudios mecánicos sugieren la sinoxipaladación para los alcoholes y la antioxipaladación para los ácidos carboxílicos.

Conclusiones:

Se ha establecido un versátil protocolo de ciclización oxidativa catalizada por paladio (II).
La reacción procede con un amplio alcance de sustrato y ofrece resultados estereoquímicos sintonizables.
La comprensión de la vía de oxipaladación es fundamental para un mayor desarrollo de catalizadores y reacciones.

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