1964 Volume 37 Issue 12 Pages 1740-1744
2-Oxo-3-ethoxycarbonylmethylenepiperazine (IV) and its 6-methyl derivative (V) have been synthesized by the reactions of diethyl acetylenedicarboxylate with ethylenediamine and propylenediamine. These compounds (IV and V), the previously-reported diethyl N-(n-butyl)aminofumarate (VIII), 4-methyl-2-oxo-3-ethoxycarbonylmethylene-3,4,5,6- tetrahydro-2H-1,4-oxazine (X), the newly-synthesized 6-chloro-2-oxo-3-ethoxycarbonylmethylene-3,4-dihydro-2H-1,4-benzoxazine (XII), and 2-oxo-3-ethoxycarbonylmethylene-1,2, 3,4-tetrahydrobenzoquinoxaline (XIV) have been hydrolyzed with 6N hydrochloric acid. The compound XIV has been hydrolyzed, with decarboxylation, to give 2-oxo-3-methyl-1,2-dihydrobenzoquinoxaline, while all the other compounds have been hydrolyzed into pyruvic acid, carbon dioxide, and the amines by the splitting of the carbon-nitrogen bond.
These two types of hydrolyses shown by the compounds have been discussed in connection with their tautomerism between enamine and ketimine forms.
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