Synthesis 2009(7): 1185-1189  
DOI: 10.1055/s-0028-1088014
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of 11H-Indolo[3,2-c]quinoline-6-carboxylic Acids by Cascade Autoxidation-Ring Contractions

Anja Beckera, Simone Kohfelda, Tanja Piesb, Karen Wiekingb, Lutz Preua, Conrad Kunick*a
a Institut für Pharmazeutische Chemie, Technische Universität Carolo-Wilhemina zu Braunschweig, Beethovenstr. 55, 38106 Braunschweig, Germany
Fax: +49(531)3912799; e-Mail: c.kunick@tu-braunschweig.de;
b Institut für Pharmazie, Universität Hamburg, Bundesstr. 45, 20146 Hamburg, Germany
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Publikationsverlauf

Received 3 October 2008
Publikationsdatum:
16. März 2009 (online)

Abstract

11H-Indolo[3,2-c]quinoline-6-carboxylic acids are prepared in moderate yields from paullones [7,12-dihydroindolo[3,2-d][1]benzazepin-6(5H)-ones] by reaction with molecular oxygen in the presence of N-hydroxyphthalimide and cobalt(II) acetate. A reaction mechanism is suggested comprising initial autoxidation reaction with subsequent ring contraction.