The present invention concerns the compounds of formula (I) ##STR00001## their N-oxides, salts, stereoisomeric forms, racemic mixtures, prodrugs, esters and metabolites, wherein n is 1, 2 or 3; R.sub.1is H, CN, halo, aminoC(.dbd.O), C(.dbd.O)OH, C.sub.1-4alkyloxyC(.dbd.O), C.sub.1-4alkylC(.dbd.O), mono- or di(C.sub.1-4alkyl)aminoC(.dbd.O), arylaminoC(.dbd.O), N-(aryl)-N--(C.sub.1-4alkyl)aminoC(.dbd.O), methanimidamidyl, N-hydroxy-methanimidamidyl, mono- or di(C.sub.1-4alkyl)methanimidamidyl, Het.sub.1 or Het.sub.2; R.sub.2 is H, C.sub.1-10alkyl, C.sub.2-10alkenyl, C.sub.3-7cycloalkyl, wherein said C.sub.1-10alkyl, C.sub.2-10alkenyl and C.sub.3-7cycloalkyl may be optionally substituted; R.sub.3 is nitro, cyano, amino, halo, hydroxy, C.sub.1-4alkyloxy, hydroxyC(.dbd.O), aminoC(.dbd.O), C.sub.1-4alkyloxyC(.dbd.O), mono- or di(C.sub.1-4alkyl)aminoC(.dbd.O), C.sub.1-4alkylC(.dbd.O), methanimidamidyl, mono- or di(C.sub.1-4alkyl)methanimidamidyl, N-hydroxy-methanimidamidyl or Het.sub.1; for use as a medicine. The invention further relates to a novel subgroup of the compounds of formula (I), and to compositions comprising compounds of formula (I).