Novel all possible enantiomeric and diastereoisomeric forms of compounds of the formula ##STR1## wherein R.sub.1 is selected from the group consisting of hydrogen, halogen, alkyl and alkoxy of 1 to 5 carbon atoms, --NO.sub.2, --NH.sub.2 and mono and dialkylamino of 1 to 5 alkyl carbon atoms, n is 1 or 2, A and B have the trans configuration, one of A and B being ##STR2## R.sub.2 is hydrogen or alkyl of 1 to 5 carbon atoms, Z is --(CH.sub.2)--.sub.n2, n.sub.2 being an integer from 0 to 5 or branched alkylene of 2 to 8 carbon atoms or --CH.sub.2 --O--, Y is selected from the group consisting of phenyl, naphthyl, indenyl, heteromonocycle of 5 to 6 ring atoms and heterobicycle, all optionally having at least one substituent and the other of A and B is ##STR3## R.sub.4 and R.sub.5 individually being selected from the group consisting of hydrogen and alkyl of 1 to 5 carbon atoms or taken together with the nitrogen to which they are attached form a 5 to 6 ring heterocycle optionally containing a heteroatom selected from the group consisting of --O--, --S-- and --NH-- with the proviso 1) A is ##STR4## wherein R.sub.4 l and R.sub.5 have the above definitions and B is ##STR5## wherein R.sub.2, Z and Y have the above definition or 2) Z is --(CH.sub.2).sub.n2 -- and n.sub.2 is 0,2,3,4 or 5 or branched alkylene of 2 to 8 carbon atoms or --CH.sub.2 O-- yr 3) Y is phenyl substituted with at least one member of the group consisting of alkyl of 1 to 5 carbon atoms, alkoxy of 2 to 5 carbon atoms, --NH.sub.2 and mono and dialkylamino or 4) Y is naphthyl, indenyl, heteromonocycle of 5 to 6 ring atoms or heterobicycle, all optionally substituted with at least one substituent, except unsubstituted benzothiophene or 5) R.sub.1 is --NO.sub.2 or 6) R.sub.2 is alkyl of 4 to 5 carbon atoms or 7) R.sub.1 is hydrogen, n.sub.1 is 1, A is ##STR6## Y is selected from the group consisting of 3,4-dimethoxy-phenyl, 4-nitro-phenyl and benzothienyl and B is pyrrolidinyl or 8) R.sub.1 is hydrogen, n.sub.1 is 2, A is ##STR7## Y is selected from the group consisting of 3,4-dimethoxy-phenyl, 3,4-dichloro-phenyl, 4-trifluoromethyl-phenyl, 4-nitro-phenyl and benzothienyl and B is pyrrolidinyl and their non-toxic, pharmaceutically acceptable acid addition salts having central analgesic properties and a strong affinity for opiate receptors.