4-Amino-6-methyl- 1,2,4-triazine-3(2H)-thione-5-0ne (1) was condensed with
propargyl bromidein the presence of sodium rnethoxide to afford 3-propargylmercapto-
4-arnino-6-rnethyl-1,2,4-triazin-5-one(2) . Transformation of the latter to 8-dihydro-
3-methyl-7-methylene-4-oxo-6H-[1,2,4]TRIAZINO [3,4-b] [1,3,4] thiadiazine (3) was
performed under the condition of palladium (II) salt. Ring closure of (1) withphenacyl
bromide provides the 3-methyl-7-phenyl-4-0x0-6h [1,2,4]triazino[3,4-b] [1,3,4] THIADIAZINE.