Abstract: Compounds of formula (I) in free or salt form, where Ar1 is phenyl substituted by one or more substituents selected from halogen, cyano, nitro, and C1–C8-alkyl optionally substituted by cyano or halogen, Ar2 is phenyl optionally which is unsubstituted or substituted by one or more substituents selected from halogen, cyano, hydroxy, nitro, C1–C8-alkyl, C1–C8-haloalkyl, C1–C8-alkoxy or C1–C8-alkoxycarbonyl, R1 is C1–C8-alkyl substituted by hydroxy, C1–C8-alkoxy, acyloxy, —N(R2)R3, halogen, carboxy, C1–C8-alkoxycarbonyl, phenyl-C1–C8-alkoxycarbonyl, —CON(R4)R5 or by a monovalent cyclic organic group, R2 and R?3 are each independently hydrogen or C1–C8-alkyl, or R2 is hydrogen and R3 is acyl or SO2R6, or R2 and R3 together with the nitrogen atom to which they are attached denote a 5- or 6-membered heterocyclic group, R4 and R5 are each independently hydrogen, C1–C8-alkyl optionally substituted by hydroxy or phenyl, or phenyl optionally substituted by C1–C8-alkyl, halogen, cyano or C1–C8-alkoxy, or R4 and R5 toge