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Transferencia catalítica asimétrica de átomos de hidrógeno: hidroaminación enantioselectiva de alquenos

Benjamin G Hejna¹, Jacob M Ganley¹, Huiling Shao²

¹Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.

Journal of the American Chemical Society

|July 11, 2023

Resumen

Un nuevo método catalítico permite la hidroaminación radical altamente enantioselectiva de ésteres de enol utilizando fotocatálisis de iridio y un tiol péptido quiral. Este enfoque sintetiza eficientemente los β-amino-alcoholes protegidos con un excelente control estéreo.

Área de la Ciencia:

Química orgánica
Catálisis
La fotoquímica

Sus antecedentes:

Las reacciones basadas en radicales son cruciales en la síntesis orgánica.
La catálisis asimétrica permite la síntesis selectiva de moléculas quirales.
Es importante desarrollar métodos eficientes para la síntesis de β-amino-alcohol.

Objetivo del estudio:

Desarrollar una hidroaminación basada en radicales altamente enantioselectiva de ésteres de enol con sulfonamidas.
Establecer un sistema catalítico que incluya un fotocatalizador Ir, una base de Brønsted y un tiol tetrapeptido quiral.
Investigar las relaciones estructura-selectividad y los aspectos mecanicistas de la reacción.

Principales métodos:

Utilizó un fotocatalizador de iridio para la generación de radicales.
Se empleó un tiol tetrapeptido quiral para la inducción asimétrica a través de la transferencia de átomos de hidrógeno.
Variaciones estructurales del sustrato y del catalizador investigadas.
Realizó estudios mecanicistas experimentales y computacionales.

Principales resultados:

Se han sintetizado con éxito 23 productos β-amino-alcohólicos protegidos con altas enantioselectividades (hasta 97:3 er).
Demostró que la estereoquímica está controlada por la transferencia selectiva de átomos de hidrógeno desde el tiol quiral.
Se han identificado las principales interacciones no covalentes (enlace hidrógeno, apilamiento π-π, dispersión de Londres) que influyen en la enantioinducción.

Conclusiones:

El método desarrollado proporciona una ruta eficiente a los β-aminoalcoholes enriquecidos enantioméricamente.
El estudio avanza en el campo de la catálisis asimétrica basada en radicales.
Las ideas mecanicistas destacan el papel de las interacciones no covalentes en el diseño del catalizador.

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