A process for the preparation of inhibitors of HMG-CoA reductase, such as simvastatin, from 4-silyloxytetrahydropyran-2-ones with triethylamine trihydrofluoride being used as the desilylation reagent is described. The reaction is performed in organic solvents, a mixture thereof or without solvents. It is characteristic of this reaction that no additional impurities are obtained and that it takes place without the use of additional catalysts and with low excesses of the reagent.