[Cl:1][C:2]1[CH:3]=[C:4]([CH2:9][CH2:10][CH:11]=[O:12])[CH:5]=[CH:6][C:7]=1[Cl:8].C(Cl)Cl.C[Si]([Br:20])(C)C.BrBr>O.O1CCOCC1>[Br:20][CH:10]([CH2:9][C:4]1[CH:5]=[CH:6][C:7]([Cl:8])=[C:2]([Cl:1])[CH:3]=1)[CH:11]=[O:12]To a solution of the product of example 37 (10 mmol, 2.0 g) in a mixed solvent of DCM (40 ml) with dioxane (4.0 ml) was added TMSBr (15 mmol, 2.3 g) at room temperature. After the mixture was kept at 25° C. for one hour, bromine (1.6 g, 10.0 mmol) was added. Another one hour later, the mixture was poured into water (50 ml) and extracted with DCM three times. The combined organic layers were washed with brine, dried and evaporated into dryness to give the crude title product, which was used directly in the next step reaction.
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