The present invention relates to novel compounds of the following formula, where the dotted line designates an optional bond: ##STR1## wherein "het" designates a five membered heterocyclic ring which may include 1 or 2 double bonds and 1-4 heteroatoms selected from nitrogen, oxygen or sulphur, provided that "het" may not designate a 1,2,4- or 1,3,4-oxadiazole;R.sup.1 is selected from hydrogen, lower alkyl, optionally substituted with phenyl which may be substituted with halogen, lower alkyl, or lower alkoxy, or a group R.sup.6 --CO--NH--CH.sub.2 -- or R.sup.6 --O--CO--, wherein R.sup.6 is lower alkyl, branched or unbranched, or phenyl optionally substituted with halogen, trifluoromethyl, lower alkyl, hydroxy, lower alkoxy, or lower acyloxy;R.sup.2 and R.sup.3 are the same or different, each representing hydrogen, lower alkyl, cycloalkyl (3-6 C-atoms), lower alkenyl, lower alkadienyl, lower alkynyl, optionally substituted with hydroxy, halogen or phenyl, in which the phenyl group may be substituted with halogen, trifluoromethyl, lower alkyl, hydroxy or lower alkoxy; R.sup.2 and R.sup.3 may further, respectively, be selected from trifluoromethyl or phenyl optionally substituted with halogen, trifluoromethyl, lower alkyl, hydroxy, lower alkoxy or lower acyloxy, or R.sup.2 and R.sup.3 may, respectively, be a group OR.sup.7 or SR.sup.7 wherein R.sup.7 is defined as R.sup.2 or R.sup.3, andif "het" includes 2 or more carbon atoms, R.sup.4 and R.sup.5 are the same or different, and each is defined as R.sup.2 or R.sup.3, and if "het" includes only one carbon atom, there is only one substituent, R.sup.4, on the heterocyclic ring, and R.sup.4 is defined as R.sup.2 or R.sup.3,as well as individual stereo isomers and pharmaceutically acceptable acid addition salts thereof.The invention moreover relates to methods for the preparation of the compounds of formula I, to novel intermediates, to pharmaceutical compositions containing same and to methods for the treatment of disorders, caused by malfunction of the acetylcholine (AcCh) or muscarinic system, by administering a non-toxic effective amount of a compound of formula I.