Synthesis and NMR Spectroscopic Characteristics of a Series of Hydrazide-Hydrazones Containing Furoxan Ring Derived from Isoeugenoxyacetic Acid.

A novel hydrazide, 2-methoxy-4-(3-methyfuroxan-4-yl)-5-nitrophenoxyacetylhydrazine, was prepared from isoeugenoxyacetic acid. The hydrazide was condensed with aromatic aldehydes to give a series of 20 hydrazide-hydrazones incorporating the furoxan ring. The structure of obtained compounds was determined by analytical and spectral data. It was demonstrated that the two sets of resonance signals in the ¹H-NMR and ¹³C-NMR spectra of the examined hydrazide-hydrazones are caused by E_N-C(O) and Z_N-C(O) conformers. The energy barriers for the conformation exchange were determined by ¹H-NMR-measurement at various temperatures. Among seven tested hydrazide-hydrazones, four compounds exhibit inhibition activities in vitro on human epidermis carcinoma (KB-cell) with IC₅₀ = 47, 68, 79, and 103 μg/mL. [ABSTRACT FROM AUTHOR]