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Adición enantioselectiva y organocatalítica de oximicales a las gamma/delta-hidroxi-alfa, beta-enonas: complejos de

De Run Li¹, Andiappan Murugan, J R Falck

¹Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390.

Journal of the American Chemical Society

|December 14, 2007

Resumen

Un nuevo método organocatalítico permite adiciones enantioselectivas de oxy-Michael, creando beta-hidroxi-cetonas quirales. Esta adición conjugada asimétrica utiliza un catalizador de aminas quirales y un hemiéster de ácido borónico para una síntesis eficiente de productos naturales complejos.

Área de la Ciencia:

Química orgánica es la química orgánica.
Catalización asimétrica por catálisis asimétrica.
Metodología sintética de la metodología sintética.

Sus antecedentes:

La síntesis enantioselectiva de beta-hidroxi-cetonas es crucial para la síntesis de productos naturales.
Los métodos existentes a menudo requieren condiciones duras o carecen de amplia aplicabilidad.

Objetivo del estudio:

Desarrollar una nueva reacción organocatalítica, enantioselectiva de adición oxy-Michael.
Establecer un método para sintetizar las beta-hidroxicetonas quirales a partir de precursores quirales.

Principales métodos:

Desarrollo de una adición conjugada asimétrica utilizando un hemiéster de ácido borónico generado in situ y un catalizador de amina quiral.
Utilizando el complejo intermedio amina-boronato como un sustituto de hidróxido quiral.
Eliminación oxidativa leve del boronato cíclico para obtener los productos finales.

Principales resultados:

Se logró la adición enantioselectiva de oxy-Michael a las gamma- y delta-hidroxi-alfa, beta-enonas.
Se obtienen beta-hidroxicetonas quirales en rendimientos buenos a excelentes y un alto exceso enantiomérico (ee).
Se han sintetizado con éxito los productos naturales (R,12Z,15Z)-2-hidroxi-4-oxohenicosa-12,15-dienilacetato y (+) -(S) -streptenol A.

Conclusiones:

El método organocatalítico desarrollado proporciona una ruta eficiente a las valiosas beta-hidroxicetonas quirales.
La utilidad de la reacción se demuestra a través de la síntesis de productos naturales complejos.
Esta metodología ofrece un enfoque suave y eficaz para la síntesis asimétrica.

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