The present invention relates to a process for preparing 2-[2-(2-chlorothiazol-5-yl)-2-hydroxy-ethyl]
sulfanyl-6-hydroxy-3-methyl-5-phenyl-pyrimidin-4-one or its tautomers or enantiomerically enriched forms thereof, to 2-[2-(2-chlorothiazol-5-yl)-2-hydroxy-ethyl]
sulfanyl-6-hydroxy-3-methyl-5-phenyl-pyrimidin-4-one or its tautomers or enantiomerically enriched forms thereof and to its use as an intermediate in the preparation of 2,3-dihydrothiazolo[3,2-a]pyrimidinium compounds, in particular 3-(2-chlorothiazol-5-yl)-8-methyl-7-oxo-6-phenyl-2,3-dihydrothiazolo[3,2-a]pyrimidin-4-ium-5-olate and its enantiomerically enriched forms.