Abstract Acylpyruvic acids readily react with 2, 3-diaminopyridine to form (Z)-3- acylmethylene-1 H-3, 4-di-hydropyrido [2, 3-b] pyrazin-2-ones. 5-Aryl-2, 3-dihydrofuran-2, 3- diones which can be regarded as lactones derived from γ-enolized aroylpyruvic acids react with 2, 3-diaminopyridine under mild conditions, yielding regioisomeric (Z)-2-aroylmethylene- 4 H-1, 2-dihydropyrido [2, 3-b] pyrazin-3-ones. The structure of the products and reaction ...
