The cyclisation of a number of hydrazones prepared from cyclic aminoguanidines and amidrazones and dimethyl acetylenedicarboxylate has been studied. In many cases conditions have been found for cyclisation to either 1,2,4-triazin-5-ones or 5-hydroxypyrazoles (pyrazolin-5-ones). Individual tautomers of certain products may be isolated in the solid state.
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COUNT et al. (1974) studied this question.