Synthesis, characterization of some new 1,3-oxazine-4-one derivatives containing 1,3,4-oxadiazole and 1,3,4-thiadiazole moiety with screening some of their biological activity.

Abstract

The derivatives of benzo[e][1,3]oxazine-4-one including 1,3,4-oxadiazole and 1,3,4-thiadiazole rings were prepared via ring-closure reaction of Schiff’s bases with 2-hydroxybenzoic acid in dry benzene solvent. A series of Schiff’s bases were synthesized through converted of aromatic ester to aromatic acid hydrazide by reaction with hydrazine hydrate in absolute ethanol, then treated with carbon disulfide (CS2) in alcoholic potassium hydroxide solution and acidified it with hydrochloric acid. The yield was reacted with chloroacetic acid in basic media by (additionelimination) reaction to give 2-(thio substituted)-1,3,4-oxadiazole-derivative, which stirred with thiosemicarbazide and phosphoryl chloride (POCl3) in cyclization reaction to yield thiadiazole ring associated with oxadiazole ring. Schiff’s bases were obtained in good yield by condensation reaction of the formed compound with diverse aromatic aldehydes in absolute ethanol and few drops of glacial acetic acid. The structure of compounds obtained were confirmed by spectroscopy, and spectrometry data: FT-IR, 1H-NMR, and 13C-NMR, besides melting points were recorded, and the purity was checked through T.L.C. technique. Some of these compounds were tested against bacteria, Bacillus (G+), E.Coli, and Klebsiella (G-).