[Li].C(NC(C)C)(C)C.[Li]CCCC.[C:14]([C@@H:18]1[O:22][C:21](=[O:23])[C@H:20]([CH3:24])[O:19]1)([CH3:17])([CH3:16])[CH3:15].[F:25][C:26]([F:30])([F:29])[CH2:27]I.[NH4+].[Cl-]>C1COCC1>[C:14]([C@@H:18]1[O:22][C:21](=[O:23])[C@@:20]([CH3:24])([CH2:27][C:26]([F:30])([F:29])[F:25])[O:19]1)([CH3:17])([CH3:15])[CH3:16]To a solution of lithium diiospropylamide (prepared from 13 ml of diisopropylamine and 54 ml of 1.6 M n-BuLi in hexanes in 200 ml of anhydrous THF at 0° C.) at -72° C. was added slowly 2-(s)-t-butyl-5-(s)-methyl-1,3-dioxolan-4-one (12.95 g, 81.9 mmol, Tetrahedron, 1984, 40, 1313) at such a rate as to maintain the internal temperature below -60° C. and the mixture was aged at -72° C. for an hour. 1,1,1-Trifluoro-2-iodoethane (25 g, 119 mmol) was added quickly, the reaction temperature increased to -45° C. and the mixture was aged at -72° C. for 45 min. and then allowed to warm up to -20° C. over 20 min. Saturated aq. NH4Cl was then added and the product was extracted in i-PrOAc, dried over Na2SO4, concentrated and distilled under reduced pressure to afford 7.51 g of a brown oil BP 90° C./20 mm Hg.
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