Z. Naturforsch. 2013,
68b, 700 – 706
doi:10.5560/ZNB.2013-3009
Synthesis of 6-Ethyl-1,2,9-trioxopyrrolo[3,2-f]quinoline-8-carboxylic Acid
Randa M.
Al-As'ad1,
Mustafa M.
El-abadelah1,
Salim S.
Sabri1,
Jalal A.
Zahra1, and
Wolfgang
Voelter2
1 Chemistry Department, Faculty of Science, The University of Jordan, Amman 11942, Jordan
2 Interfakultäres Institut für Biochemie, Universität Tübingen, Hoppe-Seyler-Straße 4, 72076 Tübingen, Germany
Received January 12, 2013 / published online Juli 2, 2013
Dedicated to Professor Heinrich Nöth on the occasion of his 85th birthday
Interaction of 6-amino-1-ethyl-4-oxoquinoline-3-carboxylic ester (7) with chloral hydrate and hydroxylamine hydrochloride gave the corresponding isonitroso-acetamido derivative 8 which, upon treatment with concentrated sulfuric acid, was converted regioselectively into 1,2,9-trioxopyrrolo[3,2-f]quinoline-8-carboxylic acid (3). This novel tricyclic system was isolated in good yield as a stable hydrate 3H. Structural assignments of the new compounds are based on microanalytical and spectral (MS and NMR) data.
Key words: 6-Amino-1-ethyl-4-oxoquinoline-3-carboxylic Ester, Isonitroso-acetamido Derivative, Regioselective Annelation, Stable Hydrated Isatin Moiety, 1,2,9-Trioxopyrrolo[3,2-f]quinoline Derivatives