[O:1]=[C:2]([C@H:16]([CH3:32])[C@@H:17]([O:23][C:24]([O:26][CH2:27][C:28]([Cl:31])([Cl:30])[Cl:29])=[O:25])[C@@H:18]([CH3:22])[CH2:19][CH:20]=[CH2:21])[C:3]([CH3:15])([CH3:14])[C@@H:4]([OH:13])[CH2:5][C:6]([O:8][C:9]([CH3:12])([CH3:11])[CH3:10])=[O:7].N1C=CN=C1.[CH2:38]([Si:40](Cl)([CH2:43][CH3:44])[CH2:41][CH3:42])[CH3:39].O>CN(C)C=O>[O:1]=[C:2]([C@H:16]([CH3:32])[C@@H:17]([O:23][C:24]([O:26][CH2:27][C:28]([Cl:29])([Cl:30])[Cl:31])=[O:25])[C@@H:18]([CH3:22])[CH2:19][CH:20]=[CH2:21])[C:3]([CH3:14])([CH3:15])[C@@H:4]([O:13][Si:40]([CH2:43][CH3:44])([CH2:41][CH3:42])[CH2:38][CH3:39])[CH2:5][C:6]([O:8][C:9]([CH3:12])([CH3:11])[CH3:10])=[O:7]A solution of tert-butyl (3S,6R,7S,8S)-5-oxo-3-hydroxy-4,4,6,8-tetramethyl-7-(2,2,2-trichloroethoxycarbonyloxy)-10-undecenoate (1.8 g), imidazole (0.48 g), and triethylsilyl chloride (0.68 g) in 5 mL of dimethylformamide is stirred for 2 hours at ambient temperature, then poured into water and extracted with ether. The extract is washed with sat. aq. NaCl, dried over MgSO4, filtered, and evaporated. The product is purified by chromatography on SiO2 (20:1 toluene/ethyl acetate).
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