5-Oxo Rosuvastatin Sodium Salt is used in the diastereoselective preparation of [(fluorophenyl)isopropyl-(N-methyl-N-methanesulfonamido)pyrimidinyl]-hydroxy-carbonyl-heptenoic acid as rosuvastatin calcium impurities by using Wittig olefination, desilylation and hydrolysis as the key steps.
