915095-87-3

To a solution of the fluoride VIII.1 (208kg), tetrahydrofuran (407kg) and (S)-3- hydroxytetrahydrofuran (56kg) is added potassium-terf-butanolate solution (20%) in tetrahydrofuran (388kg) within 3 hrs at 16 to 25??C temperature. After completion of the addition, the mixture is stirred for 60min at 20??C temperature. Then the conversion is determined via HPLC analysis. Water (355kg) is added within 20 min at a temperature of 21 ??C (aqueous quench). The reaction mixture is stirred for 30 min (temperature: 20??C). The stirrer is switched off and the mixture is left stand for 60 min (temperature: 20??C). The phases are separated and solvent is distilled off from the organic phase at 19 to 45??C temperature under reduced pressure. 2- Propanol (703kg) is added to the residue at 40 to 46??C temperature and solvent is distilled off at 41 to 50??C temperature under reduced pressure. 2-Propanol (162kg) is added to the residue at 47??C temperature and solvent is distilled off at 40 to 47??C temperature under reduced pressure. Then the mixture is cooled to 0??C within 1 hr 55 min. The product is collected on a centrifuge, washed with a mixture of 2- propanol (158kg) and subsequently with terf.-butylmethylether (88kg) and dried at 19 to 43??C under reduced pressure. 227kg (91 ,8%) of product are obtained as colourless solid. The identity of the product is determined via infrared spectrometry.