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La oxidación del ligando activa un rutenio (II) Precatalizador para la hidroxilación de C-H

Paul J Lauridsen¹, Yeon Jung Kim¹, Daniel P Marron¹

¹Department of Chemistry, Stanford University, 337 Campus Drive, Stanford, California 94305, United States.

Journal of the American Chemical Society

|August 12, 2024

Resumen

Los investigadores desarrollaron nuevos precatalizadores de sulfonamidato de rutenio para la hidroxilación de sp3 C-H. El precatalizador óptimo, 2h, demuestra una alta eficiencia en condiciones acuosas, desafiando las suposiciones anteriores sobre la oxidación del ligando en la catálisis.

Área de la Ciencia:

Química organometálica
Catálisis
Síntesis orgánica

Sus antecedentes:

El desarrollo de catalizadores eficientes para la hidroxilación de sp3 C-H es crucial para la síntesis orgánica.
Los complejos de rutenio (Ru) se exploran ampliamente para aplicaciones catalíticas.
Comprender el papel de la estructura del ligando en el rendimiento del catalizador es esencial.

Objetivo del estudio:

Introducir una nueva clase de precatalizadores de Ru-sulfonamidato para la hidroxilación de sp3 C-H.
Identificar un precatalizador óptimo mediante estudios de estructura y rendimiento.
Para aclarar el mecanismo de catálisis, en particular el papel de la oxidación del ligando.

Principales métodos:

Síntesis de complejos heteroelépticos de Ru.
Determinación de la estructura mediante análisis de rayos X monocristalino.
Reacciones de hidroxilación catalítica en mezclas acuosas de disolventes bifásicos.
Estudios mecanicistas comparativos que incluyen cinética, espectrometría de masas y electroquímica.

Principales resultados:

Se identificó un precatalizador óptimo, 2h (Ru-sulfonamidato con los ligandos dtbpy y piridilsulfonamidato).
La hidroxilación catalítica alcanzó rendimientos del 37-90% utilizando 1 mol% 2h y nitrato de amonio cerico.
Los estudios mecanicistas revelaron especies activas de larga vida generadas por 2h, lo que lleva a altos números de rotación.
Se descubrió que la oxidación de ligandos es un requisito previo para la activación del catalizador, contrariamente a los hallazgos anteriores.

Conclusiones:

Los nuevos precatalizadores de ru-sulfonamidato ofrecen una vía versátil y eficiente para la hidroxilación de sp3 C-H.
El precatalizador óptimo 2h presenta una alta actividad y estabilidad en medios acuosos.
Los hallazgos desafían la comprensión convencional de la oxidación del ligando en reacciones catalizadas por Ru, abriendo nuevas vías para el diseño del catalizador.

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