[O:1]1[CH:6]=[CH:5][CH2:4][CH2:3][CH2:2]1.[OH:7][C:8]1[CH:16]=[CH:15][C:11]([C:12]([OH:14])=[O:13])=[CH:10][CH:9]=1.C(Cl)Cl>C1(C)C=CC(S([O-])(=O)=O)=CC=1.[NH+]1C=CC=CC=1.CCOCC>[O:1]1[CH2:2][CH2:3][CH2:4][CH2:5][CH:6]1[O:7][C:8]1[CH:16]=[CH:15][C:11]([C:12]([OH:14])=[O:13])=[CH:10][CH:9]=1
Into a 300 ml three neck flask were charged 25.4 g of 2,3-dihydropyran (reagent, manufactured by Tokyo Kasei Kogyo Co., Ltd.), 41.4 g of p-hydroxybenzoic acid (reagent, manufactured by Tokyo Kasei Kogyo Co., Ltd.), and 3.7 g of pyridinium p-toluenesulfonate (reagent, manufactured by Tokyo Kasei Kogyo Co., Ltd.). The mixture was dissolved after addition of 20 ml of methylene chloride and 80 ml of absolute ether. After the mixture was vigorously stirred for about 3 hours, it was extracted 3 times with 70 ml of a 10% sodium hydroxide aqueous solution. The resulting extracted solution was neutralized with 1 N of hydrochloric acid until the pH is made to 6. The resulting precipitate was filtered and dried in a vacuum thereby obtaining 57.4 g of crude p-tetrahydropyranyloxy benzoic acid.
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