C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.[Br:20]Br.[OH:22][C:23]1[C:24]([CH3:39])=[C:25]([CH3:38])[C:26]2[O:31][C:30]([CH3:35])([CH2:32][CH2:33]O)[CH2:29][CH2:28][C:27]=2[C:36]=1[CH3:37]>ClCCl>[Br:20][CH2:33][CH2:32][C:30]1([CH3:35])[CH2:29][CH2:28][C:27]2[C:36]([CH3:37])=[C:23]([OH:22])[C:24]([CH3:39])=[C:25]([CH3:38])[C:26]=2[O:31]1To 11.0 g (0.042 mol) of triphenylphosphine in 200 ml of dichloromethane is added dropwise a solution of 6.71 g (0.042 mol) of bromine in 50 ml of dichloromethane. The solution is stirred for 30 min at room temperature, then 10.0 g (0.04 mol) of 3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-ethanol (CAS 79907-48-5) is added. The resulting solution is refluxed for 4 hours, allowed to cool overnight, washed with a solution of 15 g of sodium carbonate in 200 ml of water, dried over anhydrous sodium sulfate, filtered and evaporated. The resulting oil is crystallized from methanol to give 9.22 g of 3,4-dihydro-2-(2-bromoethyl)-2,5,7,8-tetramethyl-2H-1-benzopyran-6-ol.
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