This invention relates to quinoxaline-di-N-oxides, and more particularly to a unique series of 3-methylquinoxaline-di-N-oxide-2-carboxylic acid alkyl esters, substituted on the alkyl portion of the ester by hydroxy, acyloxy, N-alkyl carbamyloxy, dialkylaminoacyloxy, carboxyacyloxy, alkoxycarbonyloxy, haloacyloxy, amino and mono- and disubstituted amino and the appropriate basic, quaternary and acid addition salts thereof possessing antibacterial activity against pathogenic microorganisms and to methods for the promotion of weight gain and food consumption of animals.
Continuing efforts to uncover new and more useful antibacterial agents have led, over the years, to the development of a wide variety of prototype organic compounds including numerous congeners of quinoxaline-di-N-oxides. Landquist, et al., J. Chem. Soc., 2052 (1956), in a search for compounds of improved anitbacterial or antiprotozoal activity, reported the preparation of several derivatives of 2-methyl- and 2,3-dimethylquinoxaline-di-N-oxides in which the methyl groups were converted to groups such as bromomethyl-, acetoxymethyl- and hydroxymethyl including 3-methyl-2-carbethoxyquinoxaline-di-N-oxide. However, no utility is alleged for any of these compounds. French Pat. No. M3717, granted Jan. 3, 1966, discloses 2-quinoxaline-carboxamide-di-N-oxides in which the carboxamide group may be substituted with an alkyl, substituted alkyl, aryl, aralkyl, or cycloalkyl group. Also disclosed, but the structure not indicated, are the corresponding 2-quinoxaline-carboxylic acid substituted esters. They are reported to be of use in human therapy as antitubercular, antibacterial, anticancer, antivirus and antiprotozoal agents.
Belgian Pat. No. 697,976, granted Nov. 3, 1967, describes a variety of N-substituted derivatives of 3-methyl-2-quinoxalinecarboxamide-di-N-oxide in which the N-substituent is phenyl, substituted phenyl, dodecyl or ethyl, as well as the corresponding 3-methyl-2-carbethoxyquinoxaline-di-N-oxide. They are said to be of value as intermediates for the preparation of vegetation protection agents and pharmaceutical agents. Belgian Pat. Nos. 721,724; 721,725; 721,726; 721,727 and 721,728; published Apr. 2, 1969, describe a variety of N-substituted 3-methyl-2-quinoxalinecarboxamide-di-N-oxide derivatives wherein the N-substituent is a hydroxyalkyl, lower alkoxyalkyl, carboalkoxyalkyl, monoalkylaminoalkyl or di(alkyl)aminoalkyl group as antibacterial agents.