Transformation of 3-propargylmercapto-6 methyl-1, 2,4-triazin- 5 (2H)- one (1; R=CH3) to 3,6- dimethyl-7H- thiazolo [3,2-b] [1, 2, 4] triazin -7- one (2) is performed under basic condition. The formation of (2) may be mainly due to the high reactivity of acetylenes towards nucleophiles and isomerization of the intermediate. 

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 closu...

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 o...

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ab initio calculations at hf/6-31g* level of theory for geometry optimization and mp2/6-31g*//hf/6-31g* for a single point total energy calculation are reported for the importantenergy-minimum conformations and transition-state geometries of 1, 3-diazacyclohepta-1, 2-diene (2) and 1, 3-diazacycloocta-1, 2-diene (3). the c2 symmetric twist-chair (2-tc)conformation of 2 is calculated to be 7.4 kj...