Saxagliptin Di ketene impurity

Saxagliptin Di ketene impurity arises from the partial oxidation of the parent drug's pyrazine ring, introducing a cyclic diketene moiety at the 5-position. This impurity retains the sulfonamide and aromatic amine substituents of Saxagliptin but features a conjugated enol-ketone system, enhancing electrophilic reactivity. Structurally, it forms via intramolecular cyclization during synthetic stress, yielding a six-membered lactone-like structure. This compound serves as a critical HPLC reference standard for monitoring oxidative degradation pathways in Saxagliptin formulations.