New bronchospasmolytically active compounds exhibiting long duration of action and reduced undesired side effects of the structural formula ##STR1## and therapeutically acceptable salts thereof, in which formula R is selected from the group consisting of --C(CH.sub.3).sub.3, ##STR2## R.sup.1 is selected from the group consisting of H and R.sup.2, R.sup.2 represents the radical of the formula ##STR3## wherein R.sup.3 is selected from the group consisting of(a) H(b) alkyl groups containing 1-3 carbon atoms ##STR4## wherein R.sup.5 is selected from the group consisting of(a) OH(b) alkoxy groups containing 1-3 carbon atoms and whereinR.sup.4 is selected from the group consisting of(a) H(b) alkyl groups containing 1-3 carbon atoms, with the proviso that R.sup.3 and R.sup.4 are combined as follows:______________________________________ when R.sup.3 is then R.sup.4 is ______________________________________ H H alkyl group of 1-3 carbon atoms H or an alkyl group of 1-3 carbon atoms ##STR5## H ______________________________________ processes for the preparation thereof, chemical intermediates at their preparation, pharmaceutical preparations containing them, and their medicinal use.