Structure of the reaction product of 4-hydroxy-2,3- dioxo-4-phenylbutanoic acid 1,4-lactone with o-phenylenediamine

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Examination of the structure of the yellow product (5a), obtained by treating 4-hydroxy-2,3-dioxo-4-phenylbutanoic acid 1,4-lactone (4-phenyl-2,3-dioxobutyro-1,4-lactone) with two moles of o-phenylenediamine, by high-resolution 1H-, 13C-, and 15N-n.m.r. spectroscopy, as well as by electron-impact mass spectrometry, confirmed without ambiguity the structure of the product as the quinoxaline amide 5a. When 4-hydroxy-2,3-dioxo-4-phenylbutanoic acid 1,4-lactone is treated with o-phenylenediamine, the Schiff base is first formed, which is then converted into a quinoxaline lactone (6a). The excess of o-phenylenediamine then converted the quinoxaline lactone (6a) into the yellow product (5a). © 1985.

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Carbohydrate Research