Reactions of methyl 2-(benzyloxycarbonyl)amino-3-dimethylaminopropenoate and related compounds with hydrazines. Regiospecific synthesis of 1-substituted-4-amino-substituted-1<i>H</i>-pyrazol-5-(2<i>H</i>)-ones
In this paper the regiospecific transformations of methyl 2-(benzyloxycarbonyl)amino-3-dimethylaminopropenoate (1) with hydrazine, alkyl-, aryl- and heteroaryl-substituted hydrazines via the corresponding hydrazones 12-16 into pyrazoles 17-25 are described. Heteroaryl-substitued hydrazones 13-16 afforded by oxidation with bromine or lead tetraacetate the corresponding substituted (1,2,4-triazolo[4