Abstract: A process comprising (i) providing a mixture comprising a compound of formula (I) or isomers, stereoisomers, diastereomers, enantiomers or salts thereof; (ii) subjecting the mixture provided in (i) to fluorinating conditions in the presence of a fluorination agent selected from the group consisting of diethylamino (difluoro) sulfonium tetrafluoroborate and difluoro(morpholino) sulfonium tetrafluoroborate obtaining a mixture comprising a compound of formula (II) or isomers, stereoisomers diastereomers, enantiomers or salts thereof; (iii) optionally subjecting the mixture obtained in (ii) to deprotection conditions, obtaining a mixture comprising the compound of formula (III) or isomers, stereoisomers, diastereomers, enantiomers or salts thereof.