Synthesis of some pyridyloxymethyl-oxadiazoles, thiadiazoles and triazoles of expected pharmacological activity

Pyridyl-3-oxyacetylhydrazide (2) has been prepared by the hydrazinolysis of ester 1. The reaction of 2 with CS2/KOH gives the corresponding oxadiazole derivative (3) which on Mannich reaction with different dialkylamines furnish 3-N, N-dialkyl derivatives (4a,b). Also, condensation of 2 with phenyl isothiocyanate, benzoyl isothiocyanate, phenylisocyanate and/or aromatic carbonyl compounds afford compounds 5a-c; 7 and 8a,b respectively. Cyclization of the thiosemicarbazide derivative (5) in Cone. H2SO4 yields the thiadiazole derivative (6a,b). On the other hand, the reaction of dithiocarbazate (10) with hydrazine hydrate gives the corresponding triazole derivative (11).