Compounds of the formula ##STR1## wherein R.sub.1 is hydrogen, straight or branched alkyl of 1 to 3 carbon atoms or benzyl,R.sub.2 is straight or branched alkyl of 1 to 3 carbon atoms, orR.sub.1 and R.sub.2, together with each other and the nitrogen atom to which they are attached, are pyrrolidino, piperidino or hexamethyleneimino,A and B are each nitrogen or methylidenyl (=CH-), but other than both nitrogen or methylidenyl at the same time, andn is 2 or 3,And non-toxic, pharmacologically acceptable acid addition salts thereof; the compounds as well as the salts are useful as bronchospasmolytics.