C([N-]C(C)C)(C)C.[Li+].[Li]CCCC.C(NC(C)C)(C)C.[CH3:21][S:22][C:23]1[CH:28]=[CH:27][C:26]([C:29](=[N:37][OH:38])[CH2:30][C:31]2[CH:36]=[CH:35][CH:34]=[CH:33][CH:32]=2)=[CH:25][CH:24]=1.[Br:39][C:40]([F:47])([F:46])[C:41](OCC)=O>C1COCC1.Cl>[Br:39][C:40]([F:47])([F:46])[C:41]1[O:38][N:37]=[C:29]([C:26]2[CH:25]=[CH:24][C:23]([S:22][CH3:21])=[CH:28][CH:27]=2)[C:30]=1[C:31]1[CH:32]=[CH:33][CH:34]=[CH:35][CH:36]=1
Lithium diisopropylamide, prepared from n-BuLi (2. 5 mmol) and diisopropylamine (2.5 mmol), was added dropwise to a solution of 1-(4-methylsulfanylphenyl)-2-phenylethanone oxime (5) (257 mg, 1 mmol) in dry THF (25 mL) at −20° C. The reaction mixture was stirred at −20° C. for 1 h and then allowed to warm to room temperature for 1 h. The reaction mixture was cooled to −78° C. and ethyl bromodifluoroacetate (153 μL, 1.2 mmol) was added in one portion. After 5 h at −78° C., the reaction mixture was allowed to warm to room temperature, diluted with 1M HCl (10 mL) and extracted with CH2Cl2. The organic extracts were dried over anhydrous MgSO4, filtered and concentrated to dryness. The yellow residue was then treated with concentrated H2SO4 (25 mL) at 0° C. overnight. The reaction mixture was poured over ice-cold H2O and extracted with CH2Cl2. The organic extracts were dried over anhydrous MgSO4, filtered and concentrated. Purification by flash column chromatography with hexanes-EtOAc (4:1) yielded 6 (47 mg, 12%) as a colorless syrup: 1H NMR (CDCl3) δ 2.52 (3H, s, SMe), 7.23-7.50 (9H, m, Ar). HRMS (FAB) Calculated for C17H13BrF2NOS (MH+, 395.9865). Found: 395.9861.
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