A B C
Z. Naturforsch. 2012, 67b, 725 – 730
doi:10.5560/ZNB.2012-0131
Heterocycles [c]-Fused onto Indoloquinoxaline. Synthesis of Novel Pyrano[2',3':4,5]indolo[2,3-b]quinoxalin-2-ones
Almeqdad Y. Habashneh1, Mustafa M. El-Abadelah1, Mohammed M. Abadleh2, and Wolfgang Voelter3
1 Chemistry Department, Faculty of Science, The University of Jordan, Amman, Jordan
2 College of Pharmacy, Taibah University, Al Madinah Almonawarrah, 41477, Saudia Arabia
3 Interfakultäres Institut für Biochemie, Universität Tübingen, Hoppe-Seyler-Straße 4, 72076 Tübingen, Germany
Reprint requests to Prof. Dr. W. Voelter. E-mail: wolfgang.voelter@uni-tuebingen.de or Dr. A. Y. Habashneh. E-mail: a.habashneh@ju.edu.jo
Received May 17, 2012 / published online July 18, 2012
A synthesis of 4-methylpyrano[2,3-e]indole-2,8,9-trione (5) is achieved from 7-amino-4-methylcoumarin by adopting the classical Sandmeyer methodology. The cyclocondensation reaction of pyrano-isatin 5 with the appropriately substituted o-phenylenediamines 6 in polyphosphoric acid proceeded regioselectively to furnish the respective pyrano[2',3':4,5]indolo[2,3-b]quinoxalines 7ac. Structural assignments of the new compounds are based on microanalytical and spectral (IR, MS and NMR) data.
Key words: 7-Aminocoumarin, Regioselective Cyclization, Pyrano[2,3-e]indole-2,8,9-trione, o-Phenylenediamines, Cyclocondensation
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