Compounds of the formula ##STR1## wherein R.sub.1 --is hydrogen, alkyl of 1 to 6 carbon atoms or benzyl;R.sub.2 --is alkyl of 1 to 6 carbon atoms, cycloalkyl of 5 to 7 carbon atoms or, together with R.sub.1 and the adjacent nitrogen atom, pyrrolidino, piperidino, hexamethyleneimino, morpholino or N'-methyl-piperazino, where each of the heterocycles may have one or two alkyl of 1 to 3 carbon atoms or one or two methoxy substituents attached thereto;R.sub.3,--r.sub.4 and R.sub.5 are each hydrogen or methyl;R.sub.6 --is alkyl of 1 to 4 carbon atoms; andA--is alkylene of 2 to 4 carbon atoms;And non-toxic, pharmacologically acceptable acid addition salts thereof; the compounds as well as their salts are useful as bronchospasmolytics and bronchosecretolytics.