sodium hydroxide to hydrolyze the ester followed by treatment with oxalylchloride and h 2 n nh c s sme to form the methylthioester hydrazide compound which is cyclized in acid conditions e g aryl sulfonic acids or methanesulfonic acid in a solvent such as toluene at temperatures of 0 u00b0 c to reflux to form the 2 thiomethyl 1 3 4 thiadiazole which is demethylated under standard conditions such as with sodium thiomethoxide at elevated temperatures to form the desired 2 mercapto thiadiazole or alternatively is oxidized with a reagent such as hydrogen peroxide or metachloro perbenzoic acid followed by base hydrolysis to form the 2 hydroxy 1 3 4 thiadiazole in scheme iv intermediate 4 the heterocyclic biphenyl nitrile is treated with hydrogen sulfide to form the thioamide followed by treatment with hydrazine to form the imide hydrazone treatment of that compound with carbon disulfide forms a cyclized product the desired 2 mercapto 1 3 4 thiadiazole which can be subsequently converted to the 2 hydroxy compound in three steps by treating first with methyl iodide followed by hydrogen peroxide or meta chloroperbenzoic acid and base hydrolysis in scheme v intermediate 4 is treated with hydroxylamine followed by ethyl chloroformate at elevated temperatures to form the compound of formula ib in tautomeric form namely the 5 oxo 1 2 4 oxadiazole alternatively the product obtained with hydroxylamine is treated with thiocarbonyldiimidazole to form the 5 thiono 1 2 4 oxadiazole alternatively intermediate 4 is treated with ammonia and ammonium chloride to form the amidine which on treatment with carbon disulfide gives the 5 thiono 1 2 4 thiazole in scheme vi intermediate 4 is.