Patent ID: 8318933

Claim:
A process to prepare (3S)-5-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-3-hydroxy-(4E)-pentenoic acid of Formula V, wherein R 1 represents C 1-5 alkyl, which comprises: a) reacting (2E)-3-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methanesulfonylamino)pyrimidine]-propenal of Formula II, with a compound of Formula III a or III b wherein R′, R″ and R′″ represent alkyl, aralkyl, cycloalkyl, substituted cycloalkyl, phenyl, substituted phenyl, naphthyl, substituted naphthyl or heterocyclic residue, in the presence of a base selected from the group consisting of n-butyllithium, lithium hexamethyldisilazane, sodium hexamethyldisilazane and lithium diisopropylamine and an organic solvent, in the absence of MgBr 2 , to produce a diastereomeric mixture of compounds of Formula IV a or IV b at a temperature in the range of −78° C. to +20° C.; wherein R′, R″ and R′″ are defined as above, b) hydrolyzing the mixture of compounds of Formula IVa or IVb to its corresponding acid obtaining a mixture of compounds of Formula X isomers c) purifying compounds of Formula X by using optically pure precipitating agents in a mixture of organic solvent and water to get enantiomerically pure compound of Formula XI; and d) esterifying the compound of Formula XI to get enantiomerically pure compound of Formula V.