[O:1]=[C:2]1[CH:6]([CH2:7][C:8]2[CH:17]=[CH:16][C:11]([C:12]([O:14][CH3:15])=[O:13])=[CH:10][CH:9]=2)[CH2:5][CH2:4][O:3]1.[BrH:18]>C(O)(=O)C>[Br:18][CH2:4][CH2:5][CH:6]([CH2:7][C:8]1[CH:17]=[CH:16][C:11]([C:12]([O:14][CH3:15])=[O:13])=[CH:10][CH:9]=1)[C:2]([OH:3])=[O:1]9.00 g (38.42 mmol) of methyl 4-[(2-oxotetrahydro-3-furanyl)methyl]benzoate from Ex. VI are suspended in 54 ml of a 33 percent strength HBr solution in glacial acetic acid, and the mixture is stirred at 80° C. for 40 min. The reaction solution is poured into ice-water and the resulting precipitate is filtered off with suction, washed with water and dried under reduced pressure at 40° C.
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