Abstract
4-Methyl-s-triazolo [4, 3-a] purin-9 (4H)-ones (IV) were synthesized by the condensation of 2-hydrazino-3-methylpurin-6 (3H)-ones (III), which were derived from the reaction of 3-methyl-2-thioxanthines (II) with hydrazine hydrate, with appropriate ortho esters. 7-Aryl-4-methyl-s-triazolo [4, 3-a] purin-9 (4H)-ones (VI) were synthesized by the oxidative cyclization of 2-arylidenehydrazino-3-methylpurin-6 (3H)-ones (V), which were derived from the reaction of III with appropriate benzaldehydes, with diethyl azodicarboxylate (DAD) or with air in glacial acetic acid. 7-Mercapto-4-methyl-s-triazolo [4, 3-a] purin-9 (4H)-ones (VII) were also prepared in a manner similar to that used for III, but using carbon disulfide, and VII were further converted into the corresponding 7-alkylthio derivatives VIII by alkylation. The treatment of III with nitrous acid afforded the corresponding 4-methyltetrazolo [1, 5-a] purin-9 (4H)-ones (IX).
