[Cl-].[Al+3].[Cl-].[Cl-].[C:5]([C:8]1[CH:17]=[C:16]2[C:11]([CH2:12][CH2:13][CH2:14][CH2:15]2)=[CH:10][C:9]=1[OH:18])(=[O:7])[CH3:6].[Br:19]Br.Cl>ClCCl>[C:5]([C:8]1[CH:17]=[C:16]2[C:11]([CH2:12][CH2:13][CH2:14][CH2:15]2)=[C:10]([Br:19])[C:9]=1[OH:18])(=[O:7])[CH3:6]
A mixture of aluminium chloride (8.15 g) and 7-acetyl-1,2,3,4-tetrahydro-6-hydroxynaphthalene (4.75 g) in dichloromethane (250 ml) was cooled to -10°. A solution of bromine (6.0 g) in dichloromethane (150 ml) was then added over 1 hour with constant stirring. The reaction mixture was allowed to warm to room temperature overnight, dilute HCl (400 ml) was added and the organic layer was separated, washed with water and dried (MgSO4). The solvent was filtered and the filtrate was evaporated to dryness leaving an oil which solidified on cooling to give 7-acetyl-5-bromo-1,2,3,4-tetrahydro-6-hydroxynaphthalene (5.3 g, 79%) mp 127°-130°.
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