Reactions of 1-amino-2-nitroguanidine with 3-nitroacrylates

The reactions of 1-amino-2-nitroguanidine with 3-nitro- acrylates afford aza-Michael adducts. The latter when refluxed in an aqueous alkaline medium undergo elimination of nitrous acid followed by shift of the resulting C=C bond into C=N position giving finally N-substituted alkylpyruvate hydrazones. These compounds can also be prepared in a one-pot procedure; NMR spectroscopy and X-ray diffraction analysis confirmed the existence of the obtained hydrazones as E-isomers.