RESUMEN
Starting from saccharin sodium, two types of the hydrazide derivatives, 3 and 11 were prepared which underwent condensation with different aromatic aldehydes to give the hydrazone derivatives 4 and 12, respectively. Moreover, the hydrazide 3 was cyclized using CS[2] in ethanolic KOH solution to afford the oxadiazole derivative 5. Reaction of the oxadiazole 5 with methyl iodide in ethanolic KOH at room temperature gave the corresponding thioether derivative 6. The thiosemicarbazide 7 was obtained in high yield by the reaction of the hydrazide 3 and phenyl isothiocyanate at room temperature which was cyclized either in basic media to afford the triazole derivative 8 or under acidic condition to give the thiadiazole 9. Most novel compounds have been examined for their proteolytic enzyme inhibitory activity whereas compounds 6, 9 and 12h showed the highest inhibitory activity