4H-1-BENZOTHIOPYRAN-4-ONE-3-CARBOXYLIC ACIDS AND -2H-ISOTHIAZOLO[5,4-B][1]BENZOTHIOPYRAN-3,4-DIONES AS QUINOLONE ANTIBACTERIAL ANALOGS

The endocyclic replacement of a nitrogen atom at the 1-position of qui nolone antibacterial nucleus with a sulfur atom was investigated. A se ries of 1-benzothiopyran-4-one-3-carboxylic acids 14-16 and isothiazol o-[5,4-b][1]benzothiopyran-3,4-diones 22-24, suitably functionalized w ith a fluorine atom at C-6 and heterocyclic base at C-7, were prepared . The antibacterial evaluation of the target compounds showed an activ ity comparable to that of nalidixic acid for compounds 14-16, while an increased activity against gram-positive bacteria was observed for co mpounds 22-24.