Compounds of the formula ##STR1## wherein R.sub.1 is hydrogen, benzyl, benzoyl, alkanoyl of 1 to 5 carbon atoms or --CO--(CH.sub.2).sub.p --NR'R" wherein p is 0 or an integer from 1 to 4; each of R' and R" when taken individually is hydrogen or alkyl of 1 to 4 carbon atoms; R' and R" when taken together with the nitrogen to which they are attached form a 5- or 6-membered heterocyclic ring selected from piperidino, pyrollo, pyrrolidino, morpholino and N-alkylpiperazino having from 1 to 4 carbon atoms in the alkyl group;R.sub.2 is selected from hydrogen, alkanoyl of 1 to 6 carbon atoms and benzoyl;R.sub.3 is selected from hydrogen, methyl and ethyl;R.sub.4 is selected from hydrogen, alkyl of 1 to 6 carbon atoms and benzyl;Z is selected from:(a) alkylene having from one to nine carbon atoms;(b) -(alk.sub.1).sub.m -X-(alk.sub.2).sub.n - wherein each of (alk.sub.1) and (alk.sub.2) is alkylene having from 1 to 9 carbon atoms, with the proviso that the summation of carbon atoms in (alk.sub.1) plus (alk.sub.2) is not greater than 9;m and n are each 0 or 1;X is selected from O, S, SO and SO.sub.2 ; andW is selected from hydrogen, methyl, pyridyl, piperidyl, phenyl, monochlorophenyl, monofluorophenyl and ##STR2## wherein W.sub.1 is selected from hydrogen, phenyl, monochlorophenyl and monofluorophenyl; a is an integer from 1 to 5 and b is 0 or an integer from 1 to 4, with the proviso that the sum of a and b is not greater than 5.Compounds I and II are useful as analgesics. Compound III is useful as an intermediate for the preparation of Compounds I and II. Intermediates for the preparation of I, II and III are disclosed. A process for the use of compounds I and II to produce analgesia is also described.