Compounds of the formula ##STR1## wherein R.sub.1 is alkyl of 3 to 12 carbon atoms; unsaturated aliphatic hydrocarbyl of 3 to 20 carbon atoms comprising 1 to 3 double bonds and/or one triple bond; phenyl(alkyl of 2 to 4 carbon atoms); methylenedioxybenzyl; chlorobenzyl; indan-5-ylmethyl; indan-3-ylmethyl; phenyl(alkenyl of 2 to 4 carbon atoms); cycloalkyl of 5 to 7 carbon atoms; (cycloalkyl of 3 to 10 carbon atoms)methyl; (methylcycloalkyl of 4 to 11 carbon atoms)methyl; morpholino(alkyl of 2 to 3 carbon atoms); pyrrolidino(alkyl of 2 to 3 carbon atoms); piperidino (alkyl of 2 to 3 carbon atoms); 4-methylpiperazino(alkyl of 2 to 3 carbon atoms); or, when R.sub.3 and/or R.sub.4 are methyl or ethyl, also methyl or ethyl; R.sub.2 is hydrogen, methyl or ethyl; and R.sub.3 and R.sub.4 are each hydrogen, methyl or ethyl; and non-toxic, pharmacologically acceptable acid addition salts thereof. The compounds as well as the salts are useful as anti-ulcerogenics and secretion inhibitors.