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La adición asimétrica catalizada por el paladio de pronucleófilos a los alenos
Barry M Trost1, Christoph Jäkel, Bernd Plietker
1Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA. bmtrost@stanford.edu
Journal of the American Chemical Society
|April 10, 2003
Resumen
Este estudio introduce una eficiente alquilación asimétrica alilica catalizada por el paladio utilizando adiciones simples. Este método ofrece una estrategia altamente atómico-económica para la creación de enlaces carbono-carbono complejos con excelente estereoselectividad.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis de la catálisis.
- Síntesis asimétrica de síntesis.
Sus antecedentes:
- La economía atómica es crucial para una síntesis química eficiente.
- La alquilación asimétrica de alenos es un desafío clave en la química orgánica.
- La catálisis de paladio ofrece rutas versátiles para la formación de enlaces C-C.
Objetivo del estudio:
- Desarrollar un nuevo protocolo de alquilación alilica asimétrico y atómico-económico.
- Para utilizar la catálisis del paladio para la hidrocarbonización de los alenos.
- Para lograr una alta regionalidad y estereoselectividad en la formación de enlaces C-C.
Principales métodos:
- Empleando un catalizador de paladio (((0) derivado del dimero de trifluoroacetato de paladio y un ligando de diamina quiral.
- Catalizando la adición de ácidos de Meldrum y azlactonas a los alenos.
- Optimización de las condiciones de reacción utilizando ácido trifluoroacético o alfa-butóxido de potasio y ácido hippurico.
Principales resultados:
- Exitosa alquilación alilica asimétrica del benzilóxialqueno con varios ácidos de Meldrum, dando una alta enantioselectividad (82-99% ee).
- Síntesis eficiente de aminoácidos cuaternarios inusuales a partir de azlactonas con una excelente diastereoselectividad (13-20:1 dr) y enantioselectividad (85-94% ee).
- Demostración de un nuevo enfoque regioselectivo para la formación asimétrica de enlaces C-C.
Conclusiones:
- Se ha establecido un nuevo y eficiente protocolo de alquilación alilica asimétrica catalizada por paladio.
- Este método proporciona una estrategia atómico-económica para la síntesis de moléculas quirales.
- El protocolo demuestra una amplia aplicabilidad con diferentes pronucleófilos, logrando un alto estereocontrol.
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