Process for the preparation of a quinoline carboxylic acid

The invention relates to a new process for the preparation of a compound of the Formula I wherein R stands for methyl and pharmaceutically acceptable salts thereof which comprises reacting a compound of the general Formula V (wherein R and R stand for an aliphatic acyloxy group comprising 2-6 carbon atoms and optionally sub stituted by halogen; or for an aromatic acyloxy group comprising 7-11 carbon atoms) with an amine of the Formula VI (wherein R has the same meaning as stated above) or a salt thereof and subjecting the compound of the general Formula VII thus obtained (wherein R, R and R are as stated above) to hydrolysis after or without isolation and if desired converting the compound of the general Formula I thus obtained into a salt thereof or setting free the same from its salt. The compound of the Formula I is a known antibacterial agent. The advantage of the process of the present invention is that it makes the desired compound of the Formula I available in a simple manner, with a high yield and in a short reaction time.