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Derivatives of 5-oxy-pyrido[2,3-b]quinoxaline-9-carboxylic acid: 1173 A tricyclic system useful for the synthesis of potential intercalators
Varvaresou, Athanasia,Iakovou, Kriton
, p. 1173 - 1176 (2002)
The synthesis of a new series of 5-oxy-pyrido[2,3-b]quinoxaline-9-carboxamides 4a-i and N1,N2-Bis(5-oxy-pyrido[2, 3-b]quinoxaline-9-benzoyl)ethylenediamine (5) is reported starting from 2-chloro-3-nitropyridine. Fundamental steps of the synthetic pathway are i) preparation of 2-(3-nitro-pyridin-2-ylamino)benzoic acid (1) via copper-catalyzed condensation of 2-chloro-3-nitropyridine with o-anthranilic acid, ii) intramolecular cyclization of the acid 1 to 5-oxy-pyrido[2,3-b]quinoxaline-9-carboxylic acid (2b) upon treatment with concentrated sulfuric acid and oleum and iii) conversion of the acid 2 to the desired amides 4a-i and 5. Compounds 4a-i and 5 are oxygenated azaanalogs of phenazines, a wellknown series of intercalators with cytotoxic activity.
