[F:1][C:2]1[CH:7]=[C:6]([CH2:8][CH2:9][CH:10]=[CH2:11])[CH:5]=[C:4]([F:12])[CH:3]=1.C([Li])CCC.[I:18]I>CCCCCC.O1CCCC1>[F:1][C:2]1[CH:7]=[C:6]([CH2:8][CH2:9][CH:10]=[CH2:11])[CH:5]=[C:4]([F:12])[C:3]=1[I:18]0.41 mol 1,3 difluoro-5-(3-butenyl)-benzene was added to a dry round bottom flask with 300 ml anhydrous tetrahydrofuran. After cooling under a nitrogen atmosphere to −70° C. a solution of 0.46 mol of n-butyllithium in 280 ml hexane was added. After stirring at −70° C. for 30 minutes a mixture of 0.46 mol of Iodine in 200 ml tetrahydrofuran was added slowly over 2 hours. The reaction was left to warm to room temperature overnight. The reaction was quenched by pouring onto ice/hydrochloric acid mixture. The layers were separated and the aqueous layer extracted twice with diethyl ether (2×100 ml). The combined organic layers were washed with 50 g sodium thiosulphate in 200 ml water to remove excess iodine, then with water (2×50 ml) and dried over anhydrous sodium sulphate. Removal of the solvent yielded 126 g of the title compound as a beige solid.
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