Patent ID: 7615647

Claim:
A process for preparing atorvastatin hemicalcium salt wherein the purity is more than 99% comprising: (a) deesterifying, wherein R is an ester protecting group to (b) extracting R(R*,R*)-3 into an organic solvent or mixture of solvents, (c) adding a base of formula NR 1 R 2 R 3 wherein R 1 , R 2 and R 3 are independently selected from H, substituted or non-substituted C1 to C7 alkyl, C6 to C9 aryl, C8 to C10 aralkyl or aminoalkyl to form atorvastatin base salt, (d) isolating by precipitation of the above atorvastatin base salt and purifying when necessary, (e) converting atorvastatin base salt to atorvastatin hemicalcium salt by treatment with a calcium salt solution, and (f) isolating the atorvastatin hemicalcium salt.