Patent ID: 8455678

Claim:
A process for the preparation of a compound of formula (I), or a salt thereof, containing an amount of a compound of formula (VIII) equal to or lower than 0.05% and/or an amount of a compound of formula (IX) equal to or lower than about 0.1%, comprising: the chemoselective reduction of the carboxylate group of a compound of formula (IIa) wherein Ra is a C 1 -C 6 alkyl, to obtain a compound of formula (III), and the subsequent selective esterification of the phenolic hydroxy group of the resulting compound of formula (III) to obtain a compound of (I), wherein the chemoselective reduction comprises: a) the treatment of a compound of formula (IIa), as defined above, with sodium hydroxide or potassium hydroxide in an organic solvent to obtain a phenate intermediate of formula (X) wherein Ra is as defined above; and M + is Na + or K + ; and b) the subsequent reduction with lithium aluminium hydride in an organic solvent.