ERRATUMTo the article "4-Hydroxy-2-quinolones. 179. Synthesis, Structure, and Anti-inflammatory Activity of 4-Hydroxy-1-methyl-2-oxo-1,2-dihydroquinolin-3-ylacetic Acid and its Derivatives" -I.

Keywords: 4-R-2-oxo-1,2-dihydroquinoline-3-carboxylic acids, pKa, analgesic activity, hydrolysis.Even a brief glance at the scientific literature and patent documentation for 4-hydroxy-2-quinolones shows a very broad range of biological properties typifying them. In the series of 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acids the overwhelming number of publications relate to N-R-amides and the products of their subsequent chemical transformations. Esters have been studied much less frequently and the acids themselves hardly at all. Such a situation becomes fully understandable if one actually takes into account the diverse and well tested arsenal of highly efficient methods for synthesizing the amide derivatives [2][3][4][5][6][7][8]. Not least is the unlimited choice and availability of intermediate derivatives available from chemical industry in such syntheses in the form of primary or secondary alkyl-, aryl-, and hetarylamines. Thanks to this there is a real opportunity for a targeted change of properties of the N-R-amides obtained within very broad limits and so for achieving optimum properties. This is of particular value when carrying out work to create novel biologically active materials. Quite a number of fundamentally different methods of preparing 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acids esters are well known [2][3][4][5][6][9][10][11][12]. However, all of these are only effective in relation to the lowest alkyl esters. In the reminder of the examples it is necessary to turn to special methods (e.g., high temperature transesterification [9]) but these are unfortunately characterized by low yields.

the results of pharmacological screening there are found compounds within the substances discovered with high analgesic activity.The problem of discovering powerful and also safe medicinal preparations which efficiently prevent various kinds of pain has not lost its urgency in the course of mankind's history. In a study of the biological activity of 1-allyl-4-hydroxy-6,7-dimethoxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid (dialkylamino)-alkylamide hydrochlorides it was found that, depending on the structure of the amide part of the molecule, these compounds can either show opioid receptor antagonist properties or prove to have a totally opposite effect which marked prolongs the analgesic effect of narcotic analgesics [2]. This observation served as the grounds for carrying out a broader study of a targeted search for 4-hydroxyquinol-2-one substances with a novel form of pharmacological activity on the living organism for this class of compound, viz. as potential analgesics.

Pharmacological testing showed promise for using these compounds to develop new highly efficient opioid receptor antagonists.

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