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Descarboxilación asimétrica alilica alquilada catalizada por el paladio de los carbonatos de enol

Barry M Trost¹, Jiayi Xu, Thomas Schmidt

¹Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA. bmtrost@stanford.edu

Journal of the American Chemical Society

|November 26, 2009

Resumen

La alquilación alilica asimétrica descarboxilativa catalizada por paladio (DAAA) ofrece un método selectivo para sintetizar cetonas con centros quirales. Este estudio optimizó DAAA utilizando el ligando quiral L4, expandiendo su alcance para varias estructuras cetónicas.

Área de la Ciencia:

Química orgánica es la química orgánica.
La catálisis de la catálisis.
Síntesis asimétrica de síntesis.

Sus antecedentes:

La alquilación alilica descarboxilativa catalizada por el paladio (DAAA) es una transformación clave.
La síntesis de cetonas alfa-quirales es crucial en la química orgánica.
Los métodos existentes a menudo carecen de selectividad o un amplio alcance de sustrato.

Objetivo del estudio:

Para investigar el DAAA catalizado por el paladio de los carbonatos de allil enoles.
Para lograr una alta quimio, regio y enantioselectividad en la síntesis de cetonas.
Para sintetizar cetonas con centros alfa esteroideos cuaternarios o terciarios.

Principales métodos:

Investigación detallada del DAAA con el uso de carbonatos de allilenoles.
Cribado de los ligandos quirales para identificar el catalizador óptimo (L4).
Exploración de una amplia gama de cetonas cíclicas y acíclicas.

Principales resultados:

El ligando quiral L4 resultó óptimo para DAAA de diversas cetonas.
Síntesis exitosa de cetonas con centros cuaternarios/terciarios alfa esteroideos.
Los estudios mecánicos indicaron un mecanismo de ataque de la esfera externa S(N) 2.

Conclusiones:

DAAA proporciona una alternativa superior a la alilación directa de los enolados metálicos.
Las condiciones de reacción más suaves y el alcance más amplio del sustrato son ventajas clave.
La generación simultánea de nucleófilo y electrófilo evita las reacciones secundarias enoladas.

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