Pyrazolidin-3-one derivatives

A compound of Formula 4a ##STR26## wherein R.sup.1a and R.sup.2a are independently hydrogen, C.sub.1 -C.sub.6 alkyl, phenyl, benzyl, naphthyl, pyridyl or substituted phenyl having 1, 2, or 3 substituents selected from the group consisting of C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.6 alkylthio, chloro, fluoro, trifluoromethyl, phenyl, phenoxy, phenyl(C.sub.1 -C.sub.4 alkyl), phenyl(C.sub.1 -C.sub.4 alkoxy), cyano, carbamyl, methylenedioxy, C.sub.3 -C.sub.6 alkene, amino, --NH(C.sub.1 -C.sub.4 alkyl or benzyl), and N(C.sub.1 -C.sub.4 alkyl).sub.2 ;

• and
• provided that when R.sup.2a is phenyl or substituted phenyl, R.sup.1a may not be hydrogen or C.sub.1 -C.sub.6 alkyl and further provided that R.sup.1a and R.sup.2a may not simultaneously be hydrogen.