4_-Hydroxy Ospemifene(M2)(EZ mixture)

4'-Hydroxy Ospemifene(M2)(EZ mixture) is a metabolite-derived impurity arising from oxidative hydroxylation at the 4' position of the phenyl ring in the parent compound Ospemifene. The structure retains the benzothiophene core and terminal alkenyl side chain but features a hydroxyl group para to the thiophene linkage, with geometric isomerism (E/Z) at the double bond. This impurity forms via enzymatic or synthetic pathway oxidation, introducing steric and electronic alterations that affect pharmacokinetic stability. It serves as a critical HPLC reference standard for quantifying oxidative degradation pathways in Ospemifene formulations.