The invention relates to compounds having anti-ischaemic activity, memory enhancing activity and anti-convulsive activity of the formulae 1A and 1B ##STR1## wherein R.sub.1 +R.sub.2 together form an alkylene group having 1-3 C-atoms which may be substituted with one or more alkyl group(s) having 1-3 C-atoms and the remaining R and Z variables are defined as disclosed herein, or a pharmacologically acceptable salt thereof.