| abstract |
Previously unknown 6-fluoro-7-chloro-1-methylamino-4-oxo- 1,4-dihydroquinoline-3-carboxylic acid-boric acid anhydrides of the general formula <IMAGE> in which R and R1 denote halogen, an aliphatic acyloxy group having 2-6 carbon atoms, optionally substituted by halogen, or an aromatic acyloxy group having 7-11 carbon atoms, are valuable intermediates which can be used for preparing the antibacterial agent 6-fluoro-1-methylamino- 7-(4-methylpiperazino)-4-oxo-1,4-dihydroquinoline-3- carboxylic acid (amifloxacin). The previously unknown compounds of the formula I can be prepared by reacting a compound of the formula II <IMAGE> or a compound of the general formula III <IMAGE> where R2 denotes alkyl having 1-4 carbon atoms, with hydrogen fluoroborate of the formula <IMAGE> or a boron trihalide of the general formula <IMAGE> where X denotes fluorine, chlorine or bromine, or a complex thereof, formed with an ether, or a boron derivative of the general formula <IMAGE> where R3, R4 and R5 denote alkyl having 1-5 carbon atoms, optionally substituted by halogen, or aryl having 6-10 carbon atoms. |