[Br:1][C:2]1[CH:7]=[CH:6][C:5]([CH2:8][C:9]#[N:10])=[CH:4][C:3]=1[F:11].Br[CH2:13][CH2:14]Br.[OH-].[Na+]>C1(C)C=CC=CC=1.[Br-].C([N+](CCCC)(CCCC)CCCC)CCC.O>[Br:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2([C:9]#[N:10])[CH2:14][CH2:13]2)=[CH:4][C:3]=1[F:11]A solution of 4-bromo-3-fluorophenylacetonitrile (5 g, 23 mmoles) in toluene (20 ml) is added with 35 mmoles of 1,2-dibromoethane, a 50% NaOH aqueous solution (20 ml) and tetrabutylammonium bromide (1.6 g, 5 mmoles). The mixture is kept under stirring at room temperature for 5-12 hours, then diluted with water and extracted with ethyl acetate. The organic phase is washed with 1N HCl, then with brine, finally dried and concentrated under vacuum to give a brown solid, which is subjected to chromatography on a silica gel column (200 g), eluting with hexane-ethyl ether 1-1, to afford the product in the solid form.
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