REARRANGEMENT OF 2-(2,5-DIOXOPYRROLIDIN-1-YL)GUANIDINE: AN EFFICIENT SYNTHESIS AND STRUCTURE OF 3-(5-AMINO-1H-1,2,4-TRIAZOL-3-YL)PROPANOIC ACID AND DERIVATIVE

The reaction between aminoguanidine and succinic acid in water under acid catalysis yields a mixture of guanyl- and digyanylhydrazides of succinic acid, which turns into a poorly separable mixture of 3-(5-amino-1H-1,2,4-triazol-3-yl)propanoic acid (3) and 3,3'-(ethane-1,2-diyl)bis(1H-1,2,4-triazol-5-amine) (5) in basic media The fusion of aminoguanidine hydrochloride with succinic anhydride at 150-170 degrees C results in the regioselective formation of 2-(2,5-dioxopyrrolidin-1-yl)guanidine hydrochloride (11). Compound 11 upon heating in an aqueous solution in the presence of alkali quantitatively rearranges into 3-(5-amino-1H-1,2,4-triazol-3-yl)propanoic acid (3). This reaction represents a new rearrangement in the 2,5-dioxopyrrolidine series. Investigations by pK(a) determination, IR, NMR and X-ray revealed that compound 3 exists both in unionized and zwitterionic forms.