Pyrimidine derivatives, in particular, derivatives of uracil, occupy an important place in the chemistry of heterocyclic compounds. This is caused by the wide spread of such compounds in living matter and by biological activity of many among them. The uracil structure defines that these compounds can act both as unsaturated carbonyl and aromatic compounds thus providing a versatile reactivity. ... Although 5-diazouracil and 6-hydroxy-5-diazo-1,3- dimethyl-6H-uracil are ...