Ethyl oxamate oxide

Works on the oxidation of uric acid has unequivocally established the triazine structure > ° (9) of oxonic acid. This is further confirmed by the straightforward synthesis described by Piskala and Gut. ° The reaction of biuret (11) with potassium ethyloxalate yielded a potassium salt (24), that with ethyl oxamate, the amide of oxonic acid (25). Both these compounds were converted to 5-azauracil. An analogous reaction with diethyloxalate which should produce an ester of oxonic acid resulted in a mixture of urethane and parabanic acid, however. 

This unusual reaction is thought to proceed by an intramolecular oxidation of the methylene group by the adjacent nitro function, yielding an ethyl IV-methyl-.AI-(3-nitro-2-pyridyl)oxamate, which then cyclizes. 

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See also in sourсe #XX -- [ ]

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