[Br:1][C:2]1[CH:3]=[CH:4][C:5]([Cl:21])=[C:6]([C:8]([C:10]2[CH:15]=[CH:14][C:13]([O:16][CH2:17][CH:18]([F:20])[F:19])=[CH:12][CH:11]=2)=O)[CH:7]=1.C([SiH](CC)CC)C.B(F)(F)F.CCOCC.C(=O)(O)[O-].[Na+]>C(#N)C.CC(OC)(C)C>[Br:1][C:2]1[CH:3]=[CH:4][C:5]([Cl:21])=[C:6]([CH2:8][C:10]2[CH:11]=[CH:12][C:13]([O:16][CH2:17][CH:18]([F:20])[F:19])=[CH:14][CH:15]=2)[CH:7]=1Under Ar protection, (5-bromo-2-chloro-phenyl)-[4-(2,2-difluoroethoxy)phenyl]methanone 12o (55.7 g, 148.6 mmol) was dissolved in 400 mL acetonitrile, triethyl silane (46.54 g, 401.22 mmol) was added and cooled to 0° C., followed by the slow dropwise addition of boron trifluoride etherate (57 g, 401.22 mmol). Then the reaction mixture was heated to 50° C. and stirred for 16 hours. Thereafter, the reaction mixture was cooled to room temperature before MTBE (200 mL) was added and 300 mL saturated sodium bicarbonate solution were dropwise added, and partitioned. The organic extracts were washed with 200 mL saturated NaCl solution and combined, dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated under reduced pressure and the resulting residue was purified by column chromatography to obtain the title compound 4-bromo-1-chloro-2-[[4-(2,2-difluoroethoxy)phenyl]methyl]benzene 12p (20 g, colourless grease), yield: 20.0%. MS m/z (ESI): 362.0 [M+1].
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