Reaction of the 2-Nitroenamine in Acid

2-Nitroenamines bearing heteroaryl substituents on enamine nitrogen rearrange in acids to amidaoxime of the pyruvic acid or give the products of the intronol~cular cyclization, di-and triaza-indenes, whereas S-aryl substituted substrates yield quinoxaline oxides.Nirronic acid of the 2-nitroenamine is suggested as a primary reactive species in acid solution.I3c and' ' 3NNR ddata are discussed which provide the evidence for this interme-di~te.1 2The nitroaliphatic compounds and nitroenamines have recently attracted a widcsprend interest as useful intermediates in organic synthesis.{ have turned o u r attention to the trnnrforrnations