[S:1]1[CH2:6][CH2:5][CH2:4][S:3][CH:2]1[C:7]([O:9][C:10]([CH3:13])([CH3:12])[CH3:11])=[O:8].I[CH2:15][CH2:16][O:17][CH3:18].CC(C)([O-])C.[K+].[Cl-].[NH4+]>CN(C)C=O>[CH3:18][O:17][CH2:16][CH2:15][C:2]1([C:7]([O:9][C:10]([CH3:13])([CH3:12])[CH3:11])=[O:8])[S:3][CH2:4][CH2:5][CH2:6][S:1]1
10.2 g (46.1 mmol) of tert-butyl 1,3-dithiane-2-carboxylate and 12.0 g (64.5 mmol) of 1-iodo-2-methoxyethane were initially charged in 127 ml of dimethylformamide, the mixture was cooled to 0° C. and 6.21 g (55.3 mmol) of potassium tert-butoxide were added. The resulting reaction mixture was stirred at 0° C. for 1 h and at RT for 16 h. The reaction mixture was added to 1.5 l of a 1:2 mixture of ice and saturated aqueous ammonium chloride solution and extracted three times with 300 ml of diethyl ether. The combined organic phases were dried over magnesium sulphate and filtered, and the solvent was removed under reduced pressure. The crude product was used for the next step without further purification. Yield: 11.1 g (87% of theory)
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