ELUCIDATION OF THE MECHANISM OF PYRAZINONE FORMATION IN GLYCINE MODELSYSTEMS USING LABELED SUGARS AND AMINO AIDS

Model studies using D-[C-13]glucoses and a series of C-2, C-3, and C-4 dicarbonyl compounds with labeled [N-15/C-13]glycines have indicated that methyl-substituted pyrazines and pyrazinones formed in these mode l systems have a common intermediate. The labeling studies have also h elped to identify a new chemical transformation of alpha-dicarbonyls, affected by the amino acid, that lead to the addition of the C-2 atom of the amino acid to the alpha-dicarbonyl compounds, instead of the am ino group as in the case of the Strecker-type interaction between the two reactants. Thus, glyoxal and pyruvaldehyde can be transformed into pyruvaldehyde and 2,3-butanedione, respectively, by the amino acid. T wo pathways of formation of pyrazinones were distinguished on the basi s of the labeling experiments, one involving the reaction of 3 mol of glycine and the other the interaction of the dipeptide glycylglycine w ith an alpha-dicarbonyl compound.