Quinolone derivatives and processes for the preparation thereof

Abstract

The present invention relates to optical isomers of quinoline compounds of Formula (IA) or Formula (IA'), their pharmaceutically acceptable salts and their intermediates: ##STR1## In the above formulae, A represent nitrogen or ##STR2## in which Y represents hydrogen, halogen such as fluorine or chlorine, lower alkyl or lower alkoxy such as methoxy, or together with R.sub.1 forms --CH.sub.2 CH.sub.2 CH.sub.2 --, CH.sub.2 CH.sub.2 CH(CH.sub.3)--, --OCH.sub.2 CH.sub.2 --, --OCH.sub.2 CH(CH.sub.3)--, --SCH.sub.2 CH.sub.2 -- or --SCH.sub.2 CH(CH.sub.3)--; R.sub.1 is as defined above or represents straight chain or cyclic lower alkyl group having 1 to 3 carbon atoms, a straight chain or cyclic lower alkyl group having 1 to 3 carbon atoms which is substituted with a halogen atom, a phenyl group or a phenyl group substituted with one or two halogen atoms, such as ethyl, cyclopropyl or 2,4-difluorophenyl; R.sub.4 represents hydrogen, lower alkyl, lower alkoxy, or an amino-protecting group, such as methyl, ethyl or butoxycarbonyl; R.sub.5, R.sub.6, R.sub.7 and R.sub.8 may be the same or different and represent independently hydrogen, lower alkyl optionally substituted by amino, hydroxy or halogen, such as methyl or ethyl; and X represents hydrogen, halogen such as fluorine or chlorine, amino or lower alkyl such as methyl.