Synthesis of some polycyclic 1,2,4-triazines disposing of acidic N-H group

Article abstract of DOI:10.1002/jhet.5570370119

7-(6-Azauracil-5-yl)-isatin 1 was convened through its thiosemicarbazone 2 to 6-(6-azauracil-5-yl)-2,3-dihydro-5H-1,2,4-triazino[5,6-b]indol-3-thione 3 and through the thiosemicarbazone of appropriate isatinic acid to 2-(2- thio-6-azauracil-5-yl)-6-(6-azauracil-5-yl)-aniline 4. The course of the cyclocondensation of this compound was studied and the reaction was found to proceed in both possible ways, resulting in a mixture of compound 3 and regioisomer 6-(2-thio-6-azauracil-5-yl)-2,3-dihydro-5H-1,2,4-triazino[5,6- b]indol-3-one 5. Substituted aniline 4 was oxidized to 2,6-bis-(6-azauracil- 5-yl)-aniline 7, which served for the preparation of hydrazone 8, cyclization of which led to 1-[2,6-bis-(6-azauracil-5-yl)-phenyl]-6-azauracil-5- carbonitrile 9. This is the first tricyclic 6-azauracil with vicinal arrangement of 6-azauracil rings.