[F:1][C:2]([CH2:5][CH3:6])([F:4])[F:3].[Br-].[Mg+2].[Br-].[Br:10][C:11]1[CH:12]=[C:13]([CH:20]=[CH:21][CH:22]=1)[C:14](N(OC)C)=[O:15]>C1COCC1>[Br:10][C:11]1[CH:12]=[C:13]([C:14](=[O:15])[CH2:6][CH2:5][C:2]([F:4])([F:3])[F:1])[CH:20]=[CH:21][CH:22]=1A prepared solution of trifluoromethyl ethane-magnesium bromide (made by refluxing Mg with 1-bromo, 2-trifluoromethyl ethane in THF for 2 hours; 4.6 g=25.82 mmol) in THF was added slowly to a cold (0° C.) solution of 3-bromo-N-methoxy-N-methylbenzamide (3.5 g, 14.3 mmol) in THF. The stirring continued at room temperature for 1 hour, quenched with cold saturated aqueous NH4Cl, acidified with 1 N HCl and extracted with ethyl ether. The organic extracts were combined, dried over MgSO4 and concentrated in vacuo. The crude product was purified on silica gel (ISCO) using hexanes/EtOAc (10/1) as the eluting solvent to give 1-(3-Bromo-phenyl)-4,4,4-trifluoro-butan-1-one as a colorless oil (3.1 g, 77% yield). m/e (M−H)− 279, 1H NMR (400 MHz, DMSO-d6) δ ppm, 2.5-2.6 (m, 2 H), 3.3-3.4 (m, 2 H), 7.5 (t, J=7.9 Hz, 1 H), 7.8-7.8 (m, 1 H), 7.9-8.0 (m, 1 H), 8.1 (t, J=1.7 Hz, 1 H).
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