[C:1](/[C:6](=[CH:11]/[C:12]1[CH:17]=[C:16](C(C)C)[CH:15]=[CH:14][C:13]=1[Br:21])/[CH2:7][C:8]([OH:10])=O)([O:3][CH2:4][CH3:5])=[O:2].O.[C:23]([O-])([O-])=O.[K+].[K+].[Na].C(O[C:34](=[O:36])[CH3:35])(=O)C>C(O)C>[CH2:4]([O:3][C:1]([C:6]1[CH:7]=[C:8]([OH:10])[C:17]2[C:12](=[C:13]([Br:21])[CH:14]=[CH:15][C:16]=2[O:36][CH:34]([CH3:23])[CH3:35])[CH:11]=1)=[O:2])[CH3:5]12.9 g (34.8 mmol) (E)-3-carboethoxy-4-(2'-bromo-5'-isopropylphenyl)-3-butenic acid (3) were dissolved in 340 acetic anhydride and heated for 6 h in reflux. After cooling to room temperature, a solution of 200 g ice, 200 g water and 90 g K2CO3 were added. After extraction with dichloromethane, the combined organic layers were dried (MgSO4), filtered and concentrated under reduced pressure. The dried residue was dissolved in a solution of 8.40 g (389 mmol) sodium in 300 mL dry ethanol and stirred for 4 h at room temperature under Ar. The solvent was removed in vacuo and the residue was partitioned between 100 mL dichloromethane and 30 mL 2N HCl-solution. The organic phases were collected, dried (MgSO4) and concentrated under reduced pressure. The residue was recrystallized from isopropanol to give 11.7 g (95%) ethyl-8-bromo-4-hydroxy-5-isopropoxy-2-naphthoate as yellow crystals (m.p. 106° C.).
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