[C:1]([OH:9])(=O)[C:2]1C=C[CH:5]=[CH:4][CH:3]=1.[Br:10][C:11]1[CH:20]=[CH:19][C:14]([O:15][CH2:16][CH2:17][OH:18])=[CH:13][CH:12]=1.O1C=CCCC1.C1(C)C=CC(S(O)(=O)=O)=CC=1>O.C(Cl)Cl>[O:9]1[CH2:1][CH2:2][CH2:3][CH2:4][CH:5]1[O:18][CH2:17][CH2:16][O:15][C:14]1[CH:19]=[CH:20][C:11]([Br:10])=[CH:12][CH:13]=1The starting benzoic acid (I) is made by the reaction of 2-(4-bromophenoxy)ethanol (V) with dihydropyran, in the presence of methylene chloride and p-toluenesulfonic acid.H2O, to give 4-(2-tetrahydropyranyloxyethoxy)bromobenzene (VI). The bromobenzene (VI) is converted to 4-(2-tetrahydropyranyloxyethoxy)benzoic acid (VII) by reacting with magnesium, in tetrahydrofuran and dibromoethane, and then with carbon dioxide. Reaction of (VII) with methanol yields the starting benzoic acid (I). ##STR2##
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