Compounds represented by the formulae: ##STR00001## wherein each of Y, X and R individually is selected from the group consisting of hydrogen, hydroxy, halo, CF.sub.3, NO.sub.2, CN, NH.sub.2, COR.sup.1 and CO.sub.2R.sup.2 wherein R.sup.1 is selected from the group consisting of alkyl, aryl, alkaryl, and NH.sub.2, and R.sup.2 is selected from the group consisting of alkyl, aryl and aralkyl, and provided that at least one of Y, X and R is other than H; and pharmaceutically acceptable salts thereof are provided. Compounds of the above formula are useful as analgesics for treating pain, as immunomodulators and for treating drug abuse.