CS(C)=O.C(Cl)(=O)C(Cl)=O.[O:11]([CH2:19][CH2:20][CH2:21][OH:22])[Si:12]([C:15]([CH3:18])([CH3:17])[CH3:16])([CH3:14])[CH3:13].C(N(CC)CC)C.Cl>C(Cl)Cl>[O:11]([CH2:19][CH2:20][CH:21]=[O:22])[Si:12]([C:15]([CH3:17])([CH3:18])[CH3:16])([CH3:14])[CH3:13]DMSO (24 mmol) is added to oxalyl chloride (11 mmol) in 40 mL of CH2Cl2 cooled to −78° C. After 15 minutes, alcohol 46 (10 mmol) is added. After an additional 15 minutes, triethylamine (50 mmol) is added. The mixture is allowed to warm to 0° C. and then poured into 0.1 M HCl (100 mL). The phases are separated, and the aqueous phase is extracted with ethyl acetate (2×100 mL). The organic phases are washed with water (100 mL), dried over anhydrous MgSO4, and concentrated in vacuo. The mixture is purified by flash chromatography to give the product as a colorless oil.
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