Compounds of the formula ##STR1## wherein A and B, together with each other and the respective carbon atoms to which they are attached, form a phenyl or pyridine ring;R.sub.1 is hydrogen, halogen, amino, nitro, alkyl of 1 to 3 carbon atoms or alkoxy of 1 to 3 carbon atoms;R.sub.2 is hydrogen or alkoxy of 1 to 3 carbon atoms;D is alkylene of 3 to 4 carbon atoms or hydroxy(alkylene of 3 to 4 carbon atoms);R.sub.3 and R.sub.5, which may be identical to or different from each other, are each hydrogen or alkyl of 1 to 3 carbon atoms;R.sub.4 is hydrogen or alkoxy of 1 to 3 carbon atoms; andR.sub.6 is straight or branched alkyl of 1 to 6 carbon atoms or --E--R.sub.7 ;where E is straight alkylene of 2 to 4 carbon atoms or hydroxy-substituted straight alkylene of 2 to 4 carbon atoms, andR.sub.7 is ##STR2## where R.sub.8 and R.sub.9 are each hydrogen, alkyl of 1 to 3 carbon atoms or alkoxy of 1 to 3 carbon atoms;and non-toxic, pharmacologically acceptable acid addition salts thereof formed with inorganic or organic acids; the compounds as well as their salts are useful as hypotensives, antiarrhythmics and .beta.-receptor-blockers.