[CH3:1][C:2]([Si:5]([CH3:23])([CH3:22])[O:6][CH2:7][C@H:8]1[C@H:12]([CH2:13][O:14][Si:15]([C:18]([CH3:21])([CH3:20])[CH3:19])([CH3:17])[CH3:16])[C:9]21[O:11][CH2:10]2)([CH3:4])[CH3:3].[I-].[Li+]>C(Cl)Cl>[CH3:4][C:2]([Si:5]([CH3:22])([CH3:23])[O:6][CH2:7][C@H:8]1[C@H:12]([CH2:13][O:14][Si:15]([C:18]([CH3:20])([CH3:19])[CH3:21])([CH3:16])[CH3:17])[CH2:10][C:9]1=[O:11])([CH3:3])[CH3:1]A solution of 12.752 g (35.6 mmol) of [4R,5R]-4,5-bis(((1,1-dimethylethyl)-dimethylsilyl)oxymethyl)-1-oxaspiro[2,2]pentane, from Step D, in 50 mL of methylene chloride was added to a solution of 3.814 g (28.5 mmol) of lithium iodide in 200 mL of methylene chloride which had been cooled in an ice bath. After stirring the reaction mixture for 1 h at 0° C., the ice bath was removed and the reaction mixture was stirred for 20 minutes at ambient temperature. The reaction mixture was then washed with 5% aqueous sodium bicarbonate solution, 5% sodium bisulfite solution and brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give 12.317 g (96.6% crude yield) of the title compound which was taken on to the next step without purifiaction; MS DCI-NH3M/Z: 376 (M+NH4)+.
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