Olmesartan N-Oxide

Olmesartan N-Oxide is an oxidation derivative of olmesartan, featuring an N-oxide functional group at the tetrazole nitrogen. This impurity arises via oxidative degradation of the parent compound's 5-tetrazole moiety, retaining the core 4-chlorobenzene sulfonamide and 2-propyl-1H-benzimidazole-7-carboxylic acid ester scaffold. The N-oxide introduces a polar, electron-withdrawing center, altering physicochemical properties while maintaining structural homology. It serves as a critical HPLC reference standard for impurity profiling in olmesartan API synthesis.