Synthesis of novel thiadiazolotriazin-4-ones and study of their mosquito-larvicidal and antibacterial properties.

A series of novel 3-tert-butyl-7-(aryloxymethyl)-4H-[1,3,4]thiadiazolo[2,3-c][1,2,4]triazin-4-ones (5a-5n) were synthesized by refluxing 3,3-dimethyl-2-oxobutanoic acid (trimethyl pyruvic acid) (1) and thiocarbohydrazide (2) in ethanol as solvent for 12 h, to yield 3-mercapto-4-amino-6-tert-butyl-1,2,4-triazine-5(4H)-one (3) (Scheme 1), then the compound (3) was condensed with different substituted aryloxyacetic acids (4) in POCl3 at 90 °C for 8 h (Scheme 2). The structures of the newly synthesized compounds were confirmed by IR, (1)H NMR, (13)C NMR, elemental analyses and mass spectroscopic studies. Few of the synthesized compounds exhibited moderate mosquito-larvicidal and antibacterial activities.

2-Isobutyl-6-(4-meth-oxy-phen-yl)imidazo[2,1-b][1,3,4]thia-diazole.

In the title compound, C(15)H(17)N(3)OS, the dihedral angle between the statistically planar imidazo[2,1-b][1,3,4]thia-dia-zole fused-ring system (r.m.s.

2-Isobutyl-6-phenyl-imidazo[2,1-b][1,3,4]thia-diazole.

In the title compound, C(14)H(15)N(3)S, the imidazo[2,1-b][1,3,4]thia-diazole fused-ring system is close to planar, with a maximum deviation of 0.042 (1) Å, and the dihedral angle between it and the phenyl ring is 24.21 (6)°.