Synthetic studies in 6H-[1,2,4]-triazino [3,4-b][1,3,4] thiadiazines

4-Amino-6-methyl-1,2,4-triazine-3-(2H) thioxo-5-one 1 was condensed with chloroacetyl chloride to yield the corresponding 4-chloromethylamide 2. Treatment of 2 with sodium methoxide afforded the bicyclic product, 3-methyl-6H, [1,2,4] triazino [3,4-b] [1,3,4] thiadiazine-5,7 dione 3. Condensation of 1 with allyl bromide afforded 3-allylthio-4-amino-6-methyl-1,2,4-triazin-5-one 4. The latter was treated with excess of bromine to afford 7-bromomethyl 3-methyl-4-oxo-6H- [1,2,4] triazino [3,4-b] [1,3,4] thiadiazine 6 which was reacted with different nucleophiles such as morpholine and diethylamine to give 7 and 8 respectively.