US Patent 8207333 Process for preparing pure amorphous rosuvastatin calcuim

A new process for preparing pure amorphous rosuvastatin calcium, substantially free of impurities, is disclosed. A process comprising hydrolysing a C1 to C5 alkyl ester of rosuvastatin, preferably methyl rosuvastatin or tert-butyl rosuvastatin, with a base, e.g. sodium hydroxide, in the presence of an aprotic solvent, preferably tetrahydrofuran and N,N-dimethyl acetamide, or in the presence of a mixture of an aprotic solvent and water, to obtain a solution of rosuvastatin salt, which may be converted to another rosuvastatin salt using another cation, e.g. with calcium cation to obtain rosuvastatin calcium. Rosuvastatin amine salts may be obtained as well.