Rosuvastatin 3S,5R - isomer calcium

Rosuvastatin 3S,5R-isomer calcium is a stereoisomeric derivative of the parent statin drug, characterized by the (3S,5R) configuration at the pyrrole-fused chromene core. Its structure incorporates a calcium-bound lactone ring, a 2-(4-(4-chlorophenyl)-6-(1,1-dimethylethyl)-5-hydroxy-2-pyrimidinyl)pyrrole-1,3-dione scaffold, and a 5-hydroxy-3-methylglutaryl moiety. The stereochemistry at C3 and C5 positions distinguishes it from the active (3R,5S) enantiomer, rendering it pharmacologically inert. This compound arises as a synthetic byproduct during chiral resolution processes of rosuvastatin. It serves as a critical HPLC reference standard for enantiomeric purity analysis in API quality control.