[Li+].[Cl-].C1C[O:6][CH2:5]C1.Br[C:9]1[CH:10]=[C:11]([C:16]2([C:19]#[N:20])[CH2:18][CH2:17]2)[CH:12]=[C:13]([Br:15])[CH:14]=1.CN(C=O)C.[NH4+].[Cl-]>O.C(OCC)(=O)C>[Br:15][C:13]1[CH:12]=[C:11]([C:16]2([C:19]#[N:20])[CH2:18][CH2:17]2)[CH:10]=[C:9]([CH:5]=[O:6])[CH:14]=1
LiCl in THF (5.429 mL of 14% w/v, 5.233 mmol) was placed in an oven-dried 3-necked flask under nitrogen. The flask was cooled to −20° C. and 1-(3,5-dibromophenyl)cyclopropane-1-carbonitrile (1.5 g, 4.984 mmol) was added in one portion. The temperature was maintained between −20 and −10° C. for 90 minutes. DMF (400.7 mg, 424.5 μL, 5.482 mmol) was then added and the reaction allowed to warm to room temperature overnight. NH4Cl (sat. aq. soln.) was added followed by ethyl acetate and water. The mixture was extracted three times with ethyl acetate, the combined organics dried over MgSO4 and the solvent removed under reduced pressure. The crude product was purified on silica (Companion, 24 g) eluting with 2-30% EtOAc:Petrol ether to give 1-(3-bromo-5-formyl-phenyl)cyclopropane-1-carbonitrile as a white solid (1.037 g, 83%).
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