PROCESS FOR PREPARING PYRIDONECARBOXYLIC ACID DERIVATIVES

摘要

This invention provides novel pyridonecarboxylic acid derivatives having a quite high antimicrobial activity. The derivatives have the following formula: [I] wherein R1, R2 and R3 represent each a hydrogen or C1-C6 alkyl group; R4 represents an ethyl, 2-fluoroethyl, vinyl, isopropyl, isopropenyl or cyclopropyl group; and X represents CH, C-F, C-Cl or N characterized in that R2 and R3 are not hydrogen at the same time.