Rosuvastatin Impurity: N-[4-(4-fluorophenyl)-6-(1-methylethyl)-5-[(1E)-2-[(2S,4R)-tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl]ethenyl]-2-pyrimidinyl]-N-methyl-methanesulfonamide (Rosuvastatin lactone).