[Br:1][C:2]1[CH:10]=[CH:9][C:5]([C:6](O)=[O:7])=[C:4](Cl)[CH:3]=1.C[O:13][C:14]1[CH:15]=[C:16]([OH:22])[CH:17]=[C:18]([O:20][CH3:21])[CH:19]=1.C(=O)([O-])[O-].[K+].[K+].Cl>[Cu].[Cu]I.C(OCC)(=O)C.C1C=CC=CC=1.CN1CCCC1=O>[Br:1][C:2]1[CH:10]=[CH:9][C:21]2[O:20][C:18]3[CH:19]=[C:14]([OH:13])[CH:15]=[C:16]([OH:22])[C:17]=3[C:6](=[O:7])[CH2:5][C:4]=2[CH:3]=1To a mixture of 88.3 g (F.W. 235.46, 375 mmol) of 4-bromo-2-chlorobenzoic acid (3), 57.8 g (F.W. 154.165, 375 mmol) of 3,5-dimethoxyphenol (13), 93.2 g (F.W. 138.21, 670 mmol) of potassium carbonate and 400 mL of N-methyl-2-pyrrolidone was added benzene (200 mL), and the resulting solution was dried by a Dean-Stark water separator (140-170° C.) for three hours and then, 6.0 g (F.W. 63.55, 93.7 mmol) of copper (powder) and 17.8 g (F.W. 190.45, 93.7 mmol) of copper (I) iodide were added thereto and stirred at 120° C. for 30 minutes. This reaction mixture was cooled by standing and ice water and ethyl acetate were added thereto and then, the obtained solution was made pH 2 with concentrated hydrochloric acid and filtered. The organic layer was separated and then, thoroughly washed with water and subjected to salting out with a saturated sodium chloride aqueous solution. The resulting solution was dried with anhydrous magnesium sulfate and concentrated and the residue was purified by silica gel column chromatography (developing solvent; ethyl acetate:hexane=1:3) and recrystallized from ethyl acetate-hexane to obtain 75.4 g (57%) a desired compound (20). (TLC; ethyl acetate:hexane=1:2 or 1:1).
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