1,3-Oxazolones 1 and 2 were reacted with hydrazine hydrate to afford the corresponding hydrazides 3 and 4. Treatment of the hydrazides withacetylacetone, acetonylacetone, ethyl acetoacetate and diethyl malonateyielded different heterocycles. However, oxazolones 1 and 2 reacted with methyl p-aminobenzoate to afford the imidazolones 5a, 5b which were converted into the hydrazide 3a or the triazinone derivative 6 upon treating with hydrazine hydrate. The structures of the newly synthesized compounds were established using IR, 1H-NMR, EIMS, and elemental analyses. [ABSTRACT FROM AUTHOR]