[Br:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([Br:8])[CH:3]=1.[CH2:9](I)[CH3:10].[Li+].CC([N-]C(C)C)C.[NH4+].[Cl-]>C1COCC1>[Br:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([Br:8])[C:3]=1[CH2:9][CH3:10]A three necked round-bottom flask was purged with argon and then filled with dry THF (1.2 l), 1,3-dibromo benzene (121 g, 0.514 mol) and ethyl iodide (95.4 g, 0.611 mol). The mixture was cooled to −78° C. and LDA (64.2 g, 0.697 mol) (2 M in THF/n-heptane/ethyl benzene) was added slowly in a way that the temperature did not rise above −65° C. After stirring for 2.75 h the reaction was poured onto 1 l sat. aq. NH4Cl solution and stirred vigorously for 20 min. Two times extraction with DCM yielded colorless oil (167 g) which was used in the next step without further purification.
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