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Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Hidroboración asimétrica catalítica dirigida por amida de alquenos trisubstituidos dirigidos por amida
1Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0304, USA.
Journal of the American Chemical Society
|January 23, 2010
Resumen
La hidroboración catalizada por el rodio de alquenos trisubstituidos se mejora utilizando amidas beta, gamma insaturadas. Este método es estereospecífico y enantioselectivo, ofreciendo una nueva ruta a los organoboranos quirales.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis de la catálisis.
Sus antecedentes:
- Las hidroboraciones catalizadas por el rodio de alquenos trisubstituidos a menudo son lentas y propensas a la isomerización.
- Las amidas beta, gamma insaturadas presentan una clase única de sustrato para las transformaciones catalíticas.
Objetivo del estudio:
- Para investigar la hidroboración catalizada por el rodio de alquenos trisubstituidos dentro de marcos de amida beta, gamma insaturada.
- Explorar la estereospecificidad y la enantioselectividad de este nuevo sistema catalítico.
Principales métodos:
- Utilizando catalizadores de rodio con ligandos de fenolimonofosfito derivados de TADDOL.
- Utilizando el Rh ((nbd) ((2) BF ((4) como el precursor del rodio.
- Sustratos estereoisoméricos reactivos (E) y (Z) -3.
Principales resultados:
- Hidroboración fácil de alquenos trisubstituidos en amidas beta y gamma insaturadas, probablemente debido a los efectos de dirección del carbonilo y la unión al sustrato bidentado.
- Formación estereospecífica de productos diastereoméricos a partir de los isómeros (E) y (Z) -3.
- Alta enantioselectividad (91-98% ee) lograda con combinaciones específicas de ligandos.
Conclusiones:
- Desarrolló una hidroboración altamente eficiente y estereospecífica catalizada por el rodio de alquenos trisubstituidos en amidas.
- Demostró la utilidad de los ligandos derivados de TADDOL para lograr una alta enantioselectividad.
- Proporcionó una nueva vía sintética a los valiosos organoboranos quirales para la síntesis de productos aldólicos.
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