Empagliflozin Impurity 4

Empagliflozin Impurity 4 is a structurally related benzofuran derivative featuring a 1,5-benzodioxole core linked to a 6-(4-hydroxyphenyl)pyrazine moiety, differing from empagliflozin by the absence of a 4-methoxy substitution on the phenyl ring. This impurity arises during synthetic pathways via oxidative demethylation, introducing a hydroxyl group at the para-position of the aromatic ring. Its distinct electronic and steric properties enable differentiation via HPLC and mass spectrometry. Serves as a reference standard for quantifying synthetic byproduct levels in empagliflozin bulk drug substance.