Compounds of formula (I) in which R1 is 1-2C-alkoxy or 1-2C-alkoxy which is completely or mainly substituted by fluorine, R2 is 1-7C-alkyl, 3-7C-cycloalkyl or 3-7C-cycloalkylmethyl, Ar is phenyl, pyridyl, phenyl which is substituted by R3, R4 and R5 or pyridyl which is substituted by R6, R7, R8 and R9, where R3 is hydroxyl, halogen, cyano, carboxyl, trifluoromethyl, 1-4C-alkyl, 1-4C-alkoxy, 1-4C-alkoxycarbonyl, 1-4C-alkylcarbonyl, 1-4C-alkylcarbonyloxy, amino, mono- or di-1-4C-alkylamino or 1-4C-alkylcarbonylamino, R4 is hydrogen, hydroxyl, halogen, amino, trifluoromethyl, 1-4C-alkyl or 1-4C-alkoxy, R5 is hydrogen, halogen, 1-4C-alkyl or 1-4C-alkoxy, R6 is hydroxyl, halogen, cyano, carboxyl, 1-4C-alkyl, 1-4C-alkoxy, 1-4C-alkoxycarbonyl or amino, R7 is hydrogen, halogen, amino or 1-4C-alkyl, R8 is hydrogen or halogen and R9 is hydrogen or halogen, the salts of this compound, and the N-oxides of the pyridines and their salts are active bronchial therapeutics.