[CH3:1][S:2]([O:5][C:6]1[CH:7]=[CH:8][C:9]2[O:13][CH:12]([OH:14])[C:11]([CH3:16])([CH3:15])[C:10]=2[CH:17]=1)(=[O:4])=[O:3].[CH3:18][CH:19]([CH3:23])[CH2:20][CH2:21]O.O>S(=O)(=O)(O)O.C1C=CC=CC=1>[CH3:1][S:2]([O:5][C:6]1[CH:7]=[CH:8][C:9]2[O:13][CH:12]([O:14][CH2:21][CH2:20][CH:19]([CH3:23])[CH3:18])[C:11]([CH3:15])([CH3:16])[C:10]=2[CH:17]=1)(=[O:3])=[O:4]A mixture of 2,3-dihydro-3,3-dimethyl-2-hydroxybenzofuran-5-yl methanesulphonate (13g, 0.05 mole), 3-methyl-1-butanol (4.4g, 0.05 mole) and concentrated sulphuric acid (4 drops) in benzene (50 ml) was heated at reflux under a Dean and Stark trap until 0.9 ml water (0.05 mole) had been eliminated. The reaction mixture was cooled, washed with dilute aqueous sodium hydroxide solution and with water (twice) and dried over sodium sulphate. The benzene was then distilled off under reduced pressure to give 2,3-dihydro-3,3-dimethyl-2-(3-methylbutoxy)-5-benzofuranyl methanesulphonate as a yellow oil (14 g, 86% yield) which slowly solidified (melting point 35°-38° C.).
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