Synthesis, NMR spectroscopic and X-ray crystallographic studies of N-acetyl-3-butanoyltetramic acid

The reaction of N-acetylglycine p-nitrophenyl ester with the anion of an active methylene compound proceeds to give N-acetyl-3-butanoyltetramic acid. The influence of the N-acetyl group on the equilibrium between different ‘internal’ and ‘external’ tautomeric forms of N-acetyl-3-butanoyltetramic acid was investigated by 1H and 13C NMR spectroscopy. The structure of this compound was confirmed by an X-ray crystal structure determination.