P(Br)(Br)[Br:2].[CH2:5]([C:7]1[CH:8]=[C:9]([CH2:13]O)[CH:10]=[CH:11][CH:12]=1)[CH3:6].O>C1C=CC=CC=1>[Br:2][CH2:13][C:9]1[CH:10]=[CH:11][CH:12]=[C:7]([CH2:5][CH3:6])[CH:8]=1Phosphorous tribromide (5.3 ml) was added to a solution of the product from step (i) (7.6 g) in benzene (150 ml) at 0° C. After 3 hours, water (40 ml) was added and the mixture warmed to room temperature and extracted with ethyl acetate. The organic phase was dried (MgSO4) and evaporated. Purified by chromatography eluting with 2% ethyl acetate in isohexane. Yield 8.0 g.
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