Patent ID: 8809554

Claim:
A process for the preparation of a compound of formula (I-S) or a pharmaceutically acceptable salt thereof; comprising Step 1: reacting a compound of formula (V-S) with a compound of formula (VI-S), wherein A 1 is a activating group; in the presence of a coupling system; in an organic solvent; to yield the corresponding compound of formula (VII-S); Step 2: (a) reacting the compound of formula (VII-S) with a non-nucleophilic sodium base, in an organic solvent or mixture of organic solvents; to yield the corresponding salt of the compound of formula (VII-S); (b) isolating the salt of the compound of formula (VII-S) as a solid isolated salt; (c) reacting the solid isolated salt of the compound of formula (VII-S) with an acid, in an organic solvent, to yield the corresponding compound of formula (VII-S); and Step 3: removing the A 1 activating group on the compound of formula (VII-S), to yield the corresponding compound of formula (I-S).