AN IMPROVED PROCESS FOR THE PREPARATION OF QUINOLONE DERIVATIVES

摘要

: This invention relates to Novel compounds for the preparation of quinolone derivatives of the formula I. wherein R=C1-C6 alkyl, C3-C6 cycloalkyl, aryl, substituted aryl, NR1R2=diarylamino, arylalkylamino,C1-C6-dialkylamino, piprazinyl, N or C alkyl (C1-C6)substituted piperazinyl, morpholino, pyrrolidinyl, substituted pyrrolidinyl, aralkyl, substituted aralkyl etc. The present invention for preparation of compound of formula I comprises in enhaning the reactivity of the displaceable halogen (X) in the compound of the formula II towards various amines of formula III wherein R=as defined for compound of formula-I, R3=COOR6 (R6=c1-c6 alkyl, aryl, aralkyl), nitrile, a carboxamide (-CONR7R8, R7 and R8= C1-C6 alkyl, C3-C6 cycloalkyl, aralkyl), X=CI, Br, F; NR1R2= as defined above by introducing a nitro group ortho to the displaceable halo group and subsequently removing the nitro group in a conventional manner. The process of the present invention enhances the yield of the compound of the formula I and also improves the quality of the prepared compound. These compounds ciprofloxacin, enrofloxin, pefloxacin, etc) are useful as antibacterial drugs.