Quinolone- and 1,8-naphthyridin-4-one-carboxylic acids which are C-bonded in the 7-position

As novel intermediates for antibacterials, the quinolone- and 1,8-naphthyridine-4-one-carboxylic acids which are C-bonded in the 7-position of the formula I in which Y represents a carboxyl group, a nitrile group, an ester group -COOR3, or an acid amide group -CONR4R5, where R3 stands for C1-C4-alkyl, X2 stands for hydrogen, nitro, alkyl having 1 to 3 carbon atoms and halogen, in particular R1 can be alkyl having 1-4 carbon atoms, vinyl, halogenoalkyl, hydroxyalkyl, cycloalkyl having 1-6 carbon atoms or optionally substituted phenyl, R2 stands for hydrogen, alkyl having 1-3 carbon atoms which is optionally substituted by halogen, alkoxy having 1-2 carbon atoms or nitro, phenyl and for a radical and Z1 and Z2 can each be hydrogen or various organic radicals or together form a ring, and salts and esters thereof.