Bifunctional organocatalysts based on a carbazole scaffold for the synthesis of the Hajos–Wiechert and Wieland–Miescher ketones. Issue 8 (25th February 2015)

• Record Type: Journal Article
• Authors: Rubio, Omayra H.; Fuentes de Arriba, Ángel L.; Monleón, Laura M.; Sanz, Francisca; Simón, Luis; Alcázar, Victoria; Morán, Joaquín R.
• Is Part Of: Tetrahedron. Volume 71:Issue 8(2015)
• Page Start: 1297
• Page End: 1303
• Publication Date: 2015-02-25
• Subjects: Bifunctional organocatalysis -- Intramolecular aldol reaction -- Enantioselectivity -- Enamine catalysis -- Oxyanion hole; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2014.12.079
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: 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 orl -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. Graphical abstract: