Process for the preparation of quinoline carboxylic acids

A process for the preparation of a compound of the Formula (I) ##STR13## or a pharmaceutically acceptable salt thereof, which comprises the steps of:

• (a) aminating a compound of the Formula (V) ##STR14## or a pharmaceutically acceptable salt thereof, wherein R.sup.1 and R.sup.2 are each C.sub.2 to C.sub.6 aliphatic acyloxy, unsubstituted or substituted by halogen, or are each C.sub.7 to C.sub.11 aromatic acyloxy, with N-methyl-piperazine or a pharmaceutically acceptable salt thereof in an inert organic solvent at a temperature of 0.degree. to 110.degree. C. for 1 to 3 hours to yield a compound of the Formula (VII) ##STR15## or a pharmaceutically acceptable salt thereof;
• and (b) hydrolyzing the compound of the Formula (VII) or a pharmaceutically acceptable salt thereof, after or without isolation, to obtain a compound of the Formula (I), and if desired, converting the compound of the Formula (I) into a pharmaceutically acceptable salt thereof, or setting free the compound of the Formula (I) from its pharmaceutically acceptable salt.