1,1'-Thiocarbonyldiimidazole → 5,6-dihydro-1-oxo-5-thioxo-1H-pyrazolo[1,2-a][1,2,4]benzotriazine-2-carboxylic acid, ethyl ester

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Reaction Steps

2.47 g 1-(2-aminophenyl)-5-hydroxy-1H-pyrazole-4-carboxylic acid, ethyl ester and 1.78 g 1,1'-thiocarbonyl-bis-[1H-imidazole] are dissolved in 50 ml tetrahydrofuran and heated for 8 hours. The residue, after distilling off the solvent, is recrystallized from dimethylformamide to yield 2.45 g of 5,6-dihydro-1-oxo-5-thioxo-1H-pyrazolo[1,2-a][1,2,4]benzotriazine-2-carboxylic acid, ethyl ester having a melting point of 277°-282° C.; yellow needles.

Provenance & Evidence