Ezetimibe Tetrahydropyran Impurity

Ezetimibe Tetrahydropyran Impurity is a structurally related synthetic byproduct formed during Ezetimibe synthesis via a competing cyclization pathway. It retains the 4-chlorophenyl-pyridyl-pyrimidine scaffold and fluorinated indole moiety but incorporates a six-membered tetrahydropyran ring instead of the tetrahydrofuran ring in the parent compound. The oxygenated heterocycle exhibits increased steric bulk and altered polarity, affecting chromatographic retention. This impurity arises from partial oxidation of the tetrahydrofuran precursor, serving as a critical HPLC reference standard for monitoring synthetic process fidelity in Ezetimibe API batches.