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Abstract

Azo coupling of the diazotized 6-(2-aminophenyl)-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione with ethyl cyanoacetylcarbamate and diethyl malonyl-bis-carbamate has been used for preparation of the hydrazones I and II. The latter substances have been boiled in strongly acidic medium to give 2,3,4,6-tetrahydro-1,2,4-triazino[5,6-c]cinnoline-3-one (III) which has also been obtained by reduction of the mentioned diazonium salt with alkali sulphite and sebsequent cyclization of the formed hydrazine sulphonate by boiling in acid medium. In alkaline medium the hydrazones I and II have been cyclized to the nitrile IV and to 2-[2-(3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazin-6-yl)-phenyl]-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carboxylic acid (V), respectively.