(3S,8R,9R,12S)-Atazanavir is a stereoisomeric impurity of the HIV protease inhibitor Atazanavir, characterized by inverted configurations at C3, C8, C9, and C12 relative to the parent compound. Its core structure comprises a 2,3-dihydro-1,4-benzodioxin-5-one moiety linked to a 3,4-dihydro-2H-1,4-benzoxazin-2-one scaffold, with a substituted naphthyridine ring system and a tetrahydrofuran side chain exhibiting altered stereochemistry. The compound retains key functional groups, including an amide, ester, and hydroxyl moiety, but exhibits distinct conformational properties due to stereochemical inversion. This impurity arises during asymmetric synthesis and serves as a critical HPLC reference standard for chiral purity analysis of Atazanavir APIs.
