Bifunctional organocatalysts based on a carbazole scaffold for the synthesis of the Hajos–Wiechert and Wieland–Miescher ketones

Several bifunctional organocatalysts based on a carbazole scaffold containing a chiral amine and a synthetic oxyanion-hole have been synthesized and successfully applied to the synthesis of the Hajos–Wiechert and Wieland–Miescher ketones (up to 99% ee). Both enamine activation and H-bonding donor ab...

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Bibliographic Details
Published in:Tetrahedron 2015-02, Vol.71 (8), p.1297-1303
Main Authors: Rubio, Omayra H., Fuentes de Arriba, Ángel L., Monleón, Laura M., Sanz, Francisca, Simón, Luis, Alcázar, Victoria, Morán, Joaquín R.
Format: Article
Language:English
Subjects:
Activation analysis
Amines
Bifunctional organocatalysis
Carbazoles
Catalysis
Catalysts
Enamine catalysis
Enantioselectivity
Intramolecular aldol reaction
Ketones
Oxyanion hole
Scaffolds
Synthesis (chemistry)
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Summary:Several bifunctional organocatalysts based on a carbazole scaffold containing a chiral amine and a synthetic oxyanion-hole have been synthesized and successfully applied to the synthesis of the Hajos–Wiechert and Wieland–Miescher ketones (up to 99% ee). Both enamine activation and H-bonding donor ability of these catalysts were evaluated by preparing catalysts differing in the nature of the amine [(R,R)-cyclohexanediamine or l-proline], the H-bond donor functional group (sulfonamide or amide) and the number of NH bonds. Modeling studies and an X-ray structure fully support the obtained results. [Display omitted]
ISSN:0040-4020
1464-5416
DOI:10.1016/j.tet.2014.12.079