[H-].[Na+].[Br:3][C:4]1[CH:5]=[C:6]([CH2:11][C:12]#[N:13])[CH:7]=[C:8]([Br:10])[CH:9]=1.Br[CH2:15][CH2:16]Br.O>CS(C)=O>[Br:3][C:4]1[CH:5]=[C:6]([C:11]2([C:12]#[N:13])[CH2:16][CH2:15]2)[CH:7]=[C:8]([Br:10])[CH:9]=1Sodium hydride (1.601 g, 40.02 mmol) was added portionwise over 10 minutes to a solution of 2-(3,5-dibromophenyl)acetonitrile (5.0 g, 18.19 mmol) in DMSO (40 mL) at room temperature. The reaction was stirred at room temperature for 40 mins then cooled in an ice-bath whilst 1,2-dibromoethane (3.588 g, 1.646 mL, 19.10 mmol) was added dropwise. The reaction was then warmed to room temperature and stirred overnight. Water was added (100 mL) and mixture extracted with ethyl acetate/toluene (3×150 mL, 2:1). The organics were combined, washed with 1M HCl, water, and brine then dried over MgSO4, filtered and the solvent removed under reduced pressure. The crude product was purified on silica (Companion, 120 g) eluting with 1-20% EtOAc:Petrol ether to give 1-(3,5-dibromophenyl)cyclopropane-1-carbonitrile as a light yellow solid (4.56 g, 83%).
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