Collect. Czech. Chem. Commun. 1980, 45, 1379-1387

Synthesis of some 2-aryl-6-amino-2,3-dihydro-1,2,4-benzotriazin-3-ones

Jan Slouka and Vojtěch Bekárek

Analytical and Organic Chemistry Department, Palacký University, 771 46 Olomouc


Acylation of 2,4-diaminobenzene and its derivatives Ia-Ih with ethyl chloroformate gives high yields of the corresponding 2,4-bis(ethoxycarbonylamino)azobenzenes IIa-IIh which, on boiling in acid medium, are cyclized with simultaneous splitting off of the second ethoxycarbonyl group to give the mesomeric 6-amino-2-aryl-3-oxo-2,3-dihydro-1,2,4-benzotriazinium cations IIIa-IIIh; the latter have been transformed into the free bases IVa-IVh or their tautomers Va-Vh. Constitution of the prepared compounds has been studied by IR spectroscopy. Influence of medium on valence vibrations of the carbamate NH groups in the compounds II has also been studied.