SYNTHESIS OF NEW 4,5-DIHYDRO-1H-1,2,4-TRIAZOL-5-ONES

Reactions of 3-alkyl/aryl-4-amino-4, 5-dihydro-1H-1,2,4-triazol-5-ones (1) with maleic anhydride, citra-conic anhydride and glutaric anhydri de lead to the formation of 3-alkyl/aryl-4-(2, 5-dihydro-pyrrole-2, 5- dion-1-yl)-4, 5-dihydro-1H-1,2, 4-trizol-5-ones 3-alkyl/aryl-4-(3-meth yl-2, 5-dihydropyrrole-2' 5-dion-1-yl)-4, 5-dihydro-1H-1, 2, 4-triazol -5-ones (13-18) and. 3-alkyl-4-(piperidine-2, 6-dion-1-yl)-4, 5-dihydr o-1H-1, 2, 4-triazol-5-ones (22-25), respectively. These reactions hav e been found to proceed via intermediate carboxylic acid derivatives s uch as 2-4, 12, 19-21. The structural assignments of new 24 compounds are based on elemental analyses and spectral data.