Abstract
Treatment of 6-(1-methylhydrazino) uracil (I) with phenacyl bromides in methoxyethanol afforded the corresponding 3-aryl-1-methylpyrimido [4, 5-c] pyridazine-5, 7 (1H, 6H)-diones (3-aryl-6-demethyl-4-deazatoxoflavins) (II) and 3-aryl-5, 7-dioxo-1-methyl-1, 4, 5, 6, 7-pentahydropyrimido [4, 3-c] [1, 2, 4] triazines (III). Methylation of II and III with methyl iodide gave the corresponding 3-aryl-4-deazatoxoflavins (IV) and 1, 6-dimethyl-5, 7-dioxopyrimido [4, 3-c] [1, 2, 4] triazines (V). The reaction of IV with m-chloroperbenzoic acid in chloroform gave the corresponding 3-aryl-4, 4a-epoxy-4-deazatoxoflavins (VI). The oxidizing abilities of II toward alcohols were examined in comparison with those of IV from both kinetic and synthetic viewpoints. Treatment of IV with 30% aqueous caustic alkali led to the exclusive formation of 4, 8-dihydro-4-deazatoxoflavins (VII) and 4, 8-dihydro-4-deazatoxoflavin-4-ones (VIII) via intermolecular oxidation-reduction between the initially formed 4-hydroxy-4, 8-dihydro-4-deazatoxoflavins (IX) and unchanged IV. Treatment of VI with 10% aqueous sodium hydroxide gave the 6-aryl-4-hydroxy-2-methylpyridazine-3 (2H)-ones (X).
