Synthesis of New Hydrazones Containing 1,3-Diketo Moiety

A series of novel hydrazones containing a 1,3-diketo moiety, namely 3-[(2E)-2-(4-hydroxybenzylidene)hydrazino]-3-oxo-N-phenylpropanamides (6a-j), were synthesized as precursors for biologically important β-lactam and thiazolidinone derivatives. The synthesis involved the condensation of 3-methoxy-4-hydroxybenzaldehyde or 3-methoxy-4-acetyloxybenzaldehyde with various substituted malonanilic acid hydrazides. The hydrazides (4a-e) were prepared by refluxing aniline with diethyl malonate, followed by treatment with hydrazine hydrate. The structures of the synthesized compounds were confirmed by elemental analysis and spectroscopic techniques, including IR, and 1H NMR spectrometry. The purity of the compounds was ascertained by thin-layer chromatography. The synthesized hydrazones (6a-j) were obtained in good yields (62-83%) and were soluble in dimethylformamide. The present study provides a foundation for further exploration of these 1,3-diketo amino compounds as promising scaffolds for developing novel heterocyclic compounds with diverse biological activities.