Abstract
Treatment of 3-methyl-6-(1-methylhydrazino) uracil (I) with phenacyl bromides in ethanol afforded the corresponding 3-aryl-4, 8-dihydro-1, 6-dimethylpyrimido [4, 5-c]-pyridazine-5, 7 (1H, 6H)-diones (3-aryl-4, 8-dihydro-4-deazatoxoflavins) (II) and 3-aryl-1, 7-dimethyl-6, 8-dioxo-1, 4, 6, 7, 8-pentahydropyrimido [4, 3-c]-as-triazines (III). Oxidation of II with diethyl azodicarboxylate gave the corresponding 3-aryl-4-deazatoxoflavins (IV) in quantitative yields. The reaction of aryl aldehyde N-methyl-N-(3-methyluracil-6-yl)-hydrazones (VII) with triethyl orthoformate in dimethylformamide also gave the corresponding 3-aryl-4-deazatoxoflavins (IV). Compounds IV thus obtained oxidized alcohols under alkaline conditions in the dark to yield the corresponding carbonyl compounds, while they themselves were hydrogenated to compounds II. Under certain conditions, these oxidations were automatically recycled to give the corresponding carbonyl compounds in more than 100% yields.
