Compounds of the formula ##STR1## wherein A is ##STR2## and R is hydrogen, alkyl of 1 to 5 carbon atoms, alkanoyl of 1 to 5 carbon atoms, alkenyl of 3 to 5 carbon atoms, (alkoxy of 1 to 4 carbon atoms)carbonyl, or aralkyl of 7 to 11 carbon atoms optionally halo-substituted,and non-toxic, pharmacologically acceptable acid addition salts thereof. The compounds as well as their salts are useful as bradycardiacs.