Synthesis of antimicrobial agents. IV. synthesis of 1-hydroxypiperazine dihydrochloride and its applications to pyridone carboxylic acid antibacterial agents

1-Hydroxypiperazine dihydrochloride 7 was prepared and it was applied to the syntheses of new pyridone carboxylic acid antibacterial agents (PCA-antibacterial agents). 1-Cyclopropyl-6,8-difluoro-1,4-dihydro-7-(4-hydroxypiperazin-1-yl)-4-oxoquinoline-3-carboxylic acid 13 showed the most potent antibacterial activity.