3

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.

Triazine backbone is present in a large number of bioactive substances and is known for their pharmacological activities like antimicrobial, antitumour and antiviral activity. Pyrazoles are another class of heterocyclic compounds associated with significant biological activities like anti-inflammatory, anticonvulsant and antimicrobial activity. In this view, it was proposed to synthesize some novel pyrazolo[3,4-e][1,2,4]triazines from 3,7-dimethyl pyrazolo[4,3-e] oxadiazine. In the current investigation, ethyl acetoacetate was condensed with hydrazine hydrate in ethanol to give 3-methylpyrazol-5-one. The pyrazole derivative was brominated by using bromine in acetic acid as brominating agent to give 4, 4- dibromo-3-methylpyrazol-5-one. This compound was then cyclized with acetic anhydride and hydrazine hydrate to get 3, 7-dimethyl pyrazolo[4,3-e]oxadiazine. This compound on further reaction with different substituted amines generates 4-(aryl/heteroaryl)-3,7-dimethyl-pyrazolo [3,4-e][1,2,4]triazines. The synthesized compounds were screened for their antibacterial and antifungal activity against S. aureus strain of Gram positive, E. coli the strain of Gram negative and A. niger strain of fungus by standard methods. The results suggest that the compounds 4a and 4c exhibited significant antifungal activity. Gentamycin, ciprofloxacin, cefotaxime and amphotericine B were used as standard drugs. The structures of the synthesized compounds were confirmed using analytical and spectral techniques (IR, 1H NMR and Mass spectral data).