PROCESS FOR PREPARING 1-SUBSTITUTED-6-FLUORO-4-OXO-7-(1-PIPERAZINYL)-1,4-DIHYDROQUINOLINE-3-CARBOXYLIC ACID,A NOVEL INTERMEDIATE USEFUL IN SAID PROCESS, AND A PROCESS FOR PREPARING SAID INTERMEDIATE

摘要

12 Disclosed is a process for preparing 1-substituted-6-fluoro-4-oxo-7-(1-piperazin yl)-1,4-dihydroquinoline-3-carboxylic acid of the formula II II wherein R1 represents a lower alkyl, a lower cycloalkyl or 2,4-difluorophenyl, wherein 1-substituted-6-fluoro-4-oxo-7-(4-substituted-1-piperazinyl)-1,4-dihydro -quinoline-3-carboxylate boron diacetate of the formula I I wherein R2 represents a lower alkyl, or an optionally substituted phenyl, is subjected to an alkaline hydrolysis. Compounds of the forrnula II are used in medicine for the treatment of inflammatory diseases. The compound of the formula I is novel. It is obtained by a nucleophilic substitution of the halo atom in 7-position in the compound of the formula III III 13 with 1-substituted piperazine of the formula