合成路线1

The title compound has been obtained by two related ways: Condensation of glycine ethyl ester (II) with 2,4-difluoronirobenzene (I) provided the N-arylglycine (III), which was further reduced to the phenylenediamine derivative (IV) by catalytic hydrogenation. Acylation of diamine (IV) with ethyl chloroglyoxylate, followed by ring closure in refluxing ethanol, yielded the quinoxalinedione (V). Subsequent electrophyllic nitration of (V) furnished the 6-nitroquinoxaline (VI). The fluoride group of (III) was then displaced with imidazole (VII) in hot DMF yielding the imidazolyl quinoxaline (VIII). Finally, basic hydrolysis of the ethyl ester function of (VIII) gave the target carboxylic acid.