Base or copper promoted annulation reactions of α-aminohydrazones

The title compounds, obtained by 1,4-addition of sarcosine or glycine ethyl ester on conjugated azoalkenes, gave the 1-ureido-4-amino-3-methyl-1H-pyrazol-5(2H)-ones through a base promoted heterocyclization process, while in the presence of copper (I) species the 1-ureido-5-methyl-4-imidazolines and the 4-methoxycarbonyl-5-methyl-1-ureidoimidazole were obtained. The mechanism of these reactions is discussed.