Studies on Pyrimidine Derivatives. VI

Abstract

Application of formic acid to 2-hydrazino-4, 5-tetramethylene-6-hydroxypyrimidine (I) gave 5-hydroxy-6, 7-tetramethylene-[1, 2, 4]triazolo[4, 3-a] pyrimidine (II) and 5, 6-tetramethylene-7-hydroxy-[1, 2, 4]triazolo[4, 3-a] pyrimidine (III). Fusion of (II) produces 5, 6-tetramethylene-7-hydroxy-[1, 2, 4]triazolo[2, 3-a]pyrimidine (IV) which is identical with the condensation product of 5-amino-1, 2, 4-triazole (VII) and ethyl 2-oxocyclohexa-necarboxylate (VIII). Boiling of (II) with formic acid for a long time afforded (IV) with a minute amount of (III). Condensation of (VII) and 2-formylcyclohexanone (XV) afforded 5, 6- and 6, 7-tetramethylene-[1, 2, 4]triazolo[2, 3-a] pyrimidine (XVIII and XVI). The condensation product of (VII) and ethyl 2-oxocyclopentanecarboxylate (XXII) was proved to be 5, 6-trimethylene-7-hydroxy-1, 2, 4-triazolo[2, 3-a] pyrimidine (XXIII). Examinations were also made on the reaction product of 2-hydrazino-4, 5-trimethylene-6-hydroxy-pyrimidine (XXIV) and ethyl orthoformate.