| abstract |
A process for preparing quinoline carboxylic acid derivatives of general formula I wherein R1 and R3 are hydrogen or C1-4alkyl, R2 is C1-4alkyl, R4, R5 and R6 are hydrogen or halogen and pharmaceutically acceptable salts thereof, comprising reacting a compound of general of formula II wherein R denotes halogen or an aliphatic acyloxy group containing 2-6 carbon atoms or an aromatic acyloxy group containing 7 to 11 carbon atoms, R4, R5 and R6 have the meanings defined above, with a piperazine derivative of general formula III wherein R1, R2 and R3 has the meanings defined above, or with a salt thereof in the presence of an organic solvent and an acid scavenger, and subjecting the compound of general formula IV thus obtained wherein R, R1, R2 and R3 are as defined above by hydrolysis in an acidic or alkaline medium after or without isolation, and if it is desired to convert the compound of general formula thus obtained into its salt or release it from the salt. The application contains 1 more independent and 9 dependent requests. |