This search include the synthesis of some new 1,3-oxazepine derivatives have been prepared, starting from reaction of L-ascorbic acid with dry acetone in presence of dry hydrogen chloride afforded the acetal (I). Treatment of the latter with p-nitrobenzoyl chloride in dry pyridine yielded the ester (II) which was dissolved in (65%) acetic acid in absolute ethanol yielded the glycol (III). The reaction of the glycol (III) with sodium periodate in distilled water at room temperature produced the aldehyde (IV). The compound (V) [2-amino-5-mercapato-1,3,4-thiadiazole] was prepared through the reaction of thiosemicarbazide with carbon disulphide (CS2) in entity of anhydrous (Na2CO3) in (abs. ethanol ). Compound (VI) [2-(5-mercapto-1,3,4-thiadiazol-2-yl)isoindoline-1,3-dione] was synthesized by the reaction of phthalic anhydride with compound (V) in presence of (gla. CH3COOH). Reaction of compound (VI) with (ClCH2COOH) in entity of anhydrous (Na2CO3) in distilled water produced compound (VII) and then reaction with thionyl chloride yielded acid chloride (VIII). Condensation of acid chloride with hydrazine hydrate afforded 2-(5-(1,3-dioxoisoindolin-2-yl)-1,3,4-thiadiazol-2-ylthio)acetohydrazide (IX). The azomethine (X) has been synthesized from the reaction between compounds (IX) and (IV). Moreover compounds (XI-XIII) were synthesized from the cyclic condensation of Schiff base (X) with (maleic, phthalic and 3-nitrophthalic) anhydride, the structures of the novel synthesized compounds have been confirmed by physical properties and spectral measurements such as (FTIR and some of them by 1H-NMR and 13C-NMR).