This research involved synthesis heterocyclic compo unds such as (1,3,4- thiadiazole derivatives , imid azolidine derivatives, tetrazole derivatives, oxazepine deriv atives and β -Lactam derivatives ) were prepared by reaction 4- aminobenzoic acid with phenol in Acidic medium ,(0- 5)C O and sodium nitrate to get azo derivative (1) which react with thiosemicarbazide to get 1,3,4- thiadiazole de rivative (2). Derivative (2) react with benzaldehyd e derivatives (4-nitrobenzaldehyde , 2-hydroxy benzaldehyde , 2-b romobenzaldehyde , 4-hydroxybenzaldehyde ,benzaldeh yde ,4- dimethyl amino benzaldehyde, 4-Chlorobenzaldehyde a nd vanillin) to get shiff base (3-10). The cyclizat ion of Shiff base Derivatives (3,4) with α -aminoacid (tryptophan and leucine) Consecutive giv e the corresponding imidazolidine derivatives (11,12),and when cyclization of Shiff b ase Derivative (5) with sodium azide give tetrazole derivative (13). Shiff base Derivatives (6,7,8) react with (It aconic, succinic anhydride and malic anhydride ) Co nsecutive to give oxazepine derivatives (14,15,16) Consecutive. cyclization of Shiff base Derivatives (9,10) with chloroacetylchloride give the corresponding β -lactam (17,18). All this compounds characterized b y means of FT- IR, and some of the compoundes by means 1H-NMR, and 13C-NMR and follow reaction by Rf - TLC and Measur e ment melting point.