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Abstract
A novel series of 2-ethylidenehydrazono-4-substituted-5- arylazothiazoles and 3-amino-5-arylazo-2,3-dihydrothiazoles was prepared by cyclocondensation of Ü-keto hydrazonoyl halides with ethylidenethiosemi- carbazide and ethylidenethiocarbohydrazide, respectively. These cyclo- condensation reactions were achieved by using chitosan-grafted-poly- (vinylpyridine) as a novel basic catalyst. Also, reactions of ethylidenethiosemi- carbazide or ethylidenethiocarbohydrazide with N-phenyl benzenecarbo- hydrazonoyl chlorides, bereft of Ü-keto group, using grafted-chitosan, proceeded with similar mechanism and afforded the same 1,3,4-thiadiazoles as the end products. The structures of the newly synthesized compounds were established on the basis of spectroscopic evidences and their alternative synthesis by other methods. Also, the molecular mechanics calculations were used to explain the stability of these stereoselective products. Moreover, the selected newly synthesized products were evaluated for their anti-cancer activity against a colon carcinoma cell line (HCT-116) and liver carcinoma cell line )HepG-2( and the results revealed promising activity