反应详情

5.22 g 5,6-dihydro-1,5-dioxo-1H-pyrazolo[1,2-a][1,2,4]benzotriazine-2-carboxylic acid, ethyl ester, made as in Example 1, 2.76 g K2CO3 and 50 mM CH3I are dissolved in 100 ml dimethylformamide and stirred for 20 hours. The crystalline 5,6-dihydro-6-methyl-1,5-dioxo-1H-pyrazolo[1,2-a][1,2,4]benzotriazine-2-carboxylic acid, ethyl ester is isolated after filtration and recrystallized from dimethylformamide/ethanol. The yield is 4.7 g as white needles with a melting point of 243°-244° C.