[Antibacterial and antifungal agents. VI. Pirfloxacin and related compounds: synthetic and microbiological studies].

A new route to pirfloxacin, a fluorinated pyrrylquinolone with high broad-spectrum antibacterial activities, is described starting from 7-amino-1-ethyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid and 2,5-dimethoxytetrahydrofuran. When the reaction with the latter compound was carried out using the ethyl ester of the above acid the related pyrryl ester formed, which on alkaline hydrolysis gave pirfloxacin. The synthesis and antibacterial activities of the 1-allyl analogue of pirfloxacin and of 7-[2-(1-pyrrolidinomethyl)-1-pyrryl]-1-ethyl-1, 4-dihydro-4-oxoquinoline-3-carboxylic acid and its 6-fluoroderivative are also reported.