Tenofovir impurity C

Tenofovir impurity C is a structurally related byproduct arising from the synthetic pathway of tenofovir disoproxil fumarate. It retains the core cyclopropyl-carbonyl-phosphonate scaffold but features an additional hydroxyl group on the terminal phosphate moiety, distinguishing it from the parent compound. This impurity results from incomplete esterification during phosphonate prodrug synthesis, leading to a partially hydrolyzed phosphate ester. Its unique functional groups include a free primary amine, a furanose-like cyclic structure, and a zwitterionic phosphate center. The compound exhibits distinct chromatographic properties due to its altered hydrophilicity and ionic character. It serves as a critical HPLC reference standard for quantifying process-related impurities in tenofovir drug substance assays.