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

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Reaction Conditions

Reaction Steps

24.7 g 1-(2-aminophenyl)-5-hydroxy-1H-pyrazole-4-carboxylic acid, ethyl ester and 16.2 g 1,1'-carbonyl-bis-[1H-imidazole] are dissolved in 300 ml tetrahydrofuran and stirred for 8 hours at room temperature and one hour at 90° C. The solid residue, after distilling off the solvent, is recrystallized from dimethylformamide to yield 21 g of 5,6-dihydro-1,5-dioxo-1H-pyrazolo[1,2-a][1,2,4]-benzotriazine-2-carboxylic acid, ethyl ester having a melting point of 269°-271° C.; white-yellow crystals.

Provenance & Evidence