Abstract
3, 4-Disubstituted 1-methylpyrimido [4, 5-c] pyridazine-5, 7 (1H, 6H)-diones (3, 4-disubstituted 4-deazatoxoflavins) and their analogues (II) were synthesized by the condensation of 6-(1-methylhydrazino) uracil derivatives (I) and appropriate α-diketones. Reduction of II with sodium dithionite in aqueous ammonia gave the corresponding 3, 4-disubstituted 4, 8-dihydro-4-deazatoxoflavins (III). Ethylation of IIf with ethyl iodide yielded the corresponding 3, 4-disubstituted 6-ethyl-4-deazatoxoflavin (VI). Treatment of IIh with chloromethylated polystyrene and potassium carbonate in dimethylformamide (DMF) gave the corresponding 3, 4-disubstituted 4-deazatoxoflavin resin (VII). The reaction of II with m-chloroperbenzoic acid in chloroform gave the corresponding 3, 4-disubstituted 4, 4a-epoxy-4-deazatoxoflavins (IV). Treatment of IV with 10% aqueous sodium carbonate resulted in the formation of oxazolonopyridazine derivatives (V). The oxidizing abilities of II, VI, and VII toward amines were examined to explore the usefulness of these compounds as oxidation-reduction catalysis. These compounds (II, VI, and VII) oxidized long-chain alkylamines such as n-octylamine, n-dodecylamine besides benzylamine and cyclohexylamine to yield the corresponding carbonyl compounds (via imines) catalytically with a remarkably high turnover number.
