Compounds of formula (I) wherein X1, X3 X4 and X6, each independently of the others, represents a nitrogen atom or CR2, with the proviso that at least one of X1, X3 X4 and X6 represents a nitrogen atom X2 represents C—H, C—(C1-C6alkyl), C—(C1-C6alkoxy), C-halogen, C—COOH X5 represents C—H or C—(C1-C6alkyl), C-halogen R1 and R2, independently of one another, represent hydrogen or a substituent selected from hydroxy, halogen, carboxy, amino, C1-C6alkylamino, di(C1-C6alkyl)amino, mercapto, cyano, nitro, C1-C6alkyl, C1-C6alkoxy, C1-C6alkylthio, C1-C6alkylamino-carbonyloxy, C2-C6alkenyl, C2-C6alkynyl, C1-C6alkylcarbonyloxy, C1-C6alkyl-sulfonyloxy, C1-C6heteroalkylcarbonyloxy, C5-C6heterocyclyl-carbonyloxy, C1-C6heteroalkyl, C1-C6heteroalkoxy, wherein heteroalkyl, heteroalkoxy groups or heterocyclyl comprise 1, 2 or 3 heteroatoms selected from nitrogen, oxygen and sulphur, in which substituents the alkyl moieties are unsubstituted or further substituted by halogeno, cyano, hydroxy, C1-C4alkoxy, C1-C4alkylcarbonyl, C1-C4alkoxycarbonyl, unsubstituted or substituted phenoxy or phenylcarbonyl, unsubstituted or substituted C5-C6heterocyclyl or carboxy A1 represents a divalent group of one of the formulae —O—(CH2)m—(CH2)—, —S—(CH2)m—(CH2)— or —(C═O)O—(CH2)m—(CH2)—, wherein the (CH2)m moiety is optionally substituted by C1-C4alkyl, C2-C4alkenyl, C3-C6cycloalkyl, C3-C6cycloalkylmethyl, morpholinomethyl, halogen, carboxy, hydroxy, C1-C4alkoxy C1-C4alkoxyC1-C4alkyl, C1-C4alkoxy(C1-C4alkylenoxy)C1-C4alkyl, benzyloxyC1-C4alkyl, amino, mono- or di-(C1-C4alkyl)amino or acylamino, in which substituents the alkyl moieties can be further substituted by 1 or more fluoro atoms m is 0, 1 or 2, provided that the nunber of atoms in the direct chain between the two terminal valencies of A1 is at least 3, which group A1 is linked to A2 via the terminal (CH2)-moiety A2 is a group selected from C3-C8 cycloalkylene saturated and unsaturated 4 to 8-membered heterocyclodiyl with 1, 2 or 3 heteroatoms
