The present invention relates to compounds which comprise a nitrogen-containing ring scaffold substituted by an R.sup.1 alkyl units selected from the group consisting of C.sub.1 C.sub.12 linear or branched alkyl, C.sub.3 C.sub.8 cyclic alkyl, C.sub.2 C.sub.12 linear or branched alkenyl, or haloalkyl, for example, the 2-keto-3-alkylpiperazines having the formula: ##STR00001## wherein R is selected from the group consisting of phenyl, 3-fluorophenyl, 4-fluorophenyl, 3,5-difluorophenyl, and 4-chlorophenyl; R.sup.1 is selected from the group consisting of methyl, ethyl, propyl, iso-propyl, butyl, iso-butyl, sec-butyl, tert-butyl, cyclopropyl, cyclopropylmethyl, cyclopentyl, cyclopentylmethyl, cyclohexyl, cyclohexylmethyl, benzyl, allyl, 1-methylallyl, 2-methylallyl, but-2-enyl, and propargyll; R.sup.7a is selected from the group consisting of hydrogen, --CO.sub.2H, --CONH.sub.2, --CONHCH.sub.3, and --CON(CH.sub.3).sub.2; R.sup.8 is benzyl, substituted benzyl, or naphthalen-2-ylmethyl.