Abstract: Pharmaceutical compounds of the general formula (1) have been prepared ##STR1## and non-toxic pharmaceutically acceptable salts thereof, wherein R.sub.1 is a lower alkyl, phenyl lower alkyl, amino substituted phenyl lower alkyl, nitro substituted phenyl lower alkyl, cycloalkyl lower alkyl or a lower alkenyl substituent, R.sub.2 is a member selected from the group consisting of a cyano, pyridylsulfonyl, lower alkyl substituted sulfonyl, phenylsulfonyl, lower alkyl substituted phenylsulfonyl, lower alkoxy substituted phenylsulfonyl, halogen substituted phenylsulfonyl, nitro substituted phenylsulfonyl, amino substituted phenylsulfonyl and lower alkyl amido substituted phenylsulfonyl; R.sub.3 is a hydrogen or halogen atom; and R.sub.4 is a hydrogen, lower alkyl or lower alkoxy substituent, lower denoting a straight or branched chain having from 1-4 carbon atoms. These compounds exhibit analgesic agonist activity or analgesic agonist-antagonist activities.