Synthesis, Characterization and Biological Evaluation of Novel Substituted 1,3,4-Oxadiazoles and 1,3,4-Thiadiazoles as Anthelmintic Agents

The aim of our study was to review on design, synthesis and various pharmacological activities associated with the substituted oxadiazoles and thaidiazoles. Series of 5-(2-Amino-4,5,6,7- tetrahydro-1-benzothien-3-yl) N-substituted 1,3,4-thaidiazole-2-amines(Va-e)  were prepared from thiosemicarbazides (IIIa-e) by cyclization using phosphoric acid and 5-(2-Amino-4,5,6,7- tetrahydro-1-benzothien-3-yl) N-substituted 1,3,4-oxadiazole-2-amines (IVa-e) were preparedfrom substituted thiosemicarbazides (IIIa-e)by treating with Iodine &NaOH. Compounds (IIIa-e) were prepared by treating 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbohydrazide (II) with isothiocyanates.Compound II was synthesized by treating ethyl 2-amino-4,5,6,7-tetra hydrobenzeno [b]thiophene-3-carboxylate (I) with hydrazinehydrate. Compound I was prepared by one pot synthesis fromcyclohexanone,sulphur,ethylcyanoacetate in presence of diethyl amine. All the synthesized compounds were charecterized by IR, NMR and mass spectrometry and screened for and in vitro-antihelmintic activity. They showed  moderate to good anthelmintic activity against Indian earthworm Pheretimaposthuma.