[C:1]([Si:5]([CH3:8])([CH3:7])Cl)([CH3:4])([CH3:3])[CH3:2].[Si:9]([O:16][CH2:17][CH2:18][C@H:19]([OH:23])[C:20]([CH3:22])=[CH2:21])([C:12]([CH3:15])([CH3:14])[CH3:13])([CH3:11])[CH3:10].N1C=CN=C1.OS([O-])(=O)=O.[K+]>CN(C=O)C>[Si:9]([O:16][CH2:17][CH2:18][C@H:19]([O:23][Si:5]([C:1]([CH3:4])([CH3:3])[CH3:2])([CH3:8])[CH3:7])[C:20]([CH3:22])=[CH2:21])([C:12]([CH3:15])([CH3:14])[CH3:13])([CH3:11])[CH3:10]946 mg (6.28 mmol, 1.3 equivalents) of tert-butyldimethylchlorosilane is added to a solution of 1.173 g (4.83 mmol) of (S)-1-[(tert-butyldimethylsilyloxy)]-4-methyl-4-penten-3-ol 10 and 855 mg (12.56 mmol, 2.6 equivalents) of imidazole in 15.0 ml of absolute DMF. The mixture is stirred for 16 hours at room temperature. It is mixed with 50 ml of an aqueous 1 M KHSO4 solution and extracted four times with 50 ml of Et2O each. The combined ether extracts are dried on MgSO4. After the solvent is distilled off in a vacuum, the residue is flash-chromatographed by a silica gel column with pentane/Et2O (20:1). As an alternative to this aqueous working-up, the reaction mixture can be chromatographed directly. By the two variations of working-up procedure, 1.643 g (4.73 mmol, 98%) of 11 is obtained.
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