[C:1]([O:4][C:5]1[C:6]([CH3:20])=[C:7]([CH3:19])[C:8]2[O:12][C:11]([CH3:14])([CH3:13])[CH:10]([CH2:15]Br)[C:9]=2[C:17]=1[CH3:18])(=[O:3])[CH3:2].[C:21]1(=[O:31])[NH:25][C:24](=[O:26])[C:23]2=[CH:27][CH:28]=[CH:29][CH:30]=[C:22]12.[K].O>CN(C)C=O>[C:1]([O:4][C:5]1[C:6]([CH3:20])=[C:7]([CH3:19])[C:8]2[O:12][C:11]([CH3:14])([CH3:13])[CH:10]([CH2:15][N:25]3[C:24](=[O:26])[C:23]4=[CH:27][CH:28]=[CH:29][CH:30]=[C:22]4[C:21]3=[O:31])[C:9]=2[C:17]=1[CH3:18])(=[O:3])[CH3:2]A mixture of 4.75 g of 5-acetoxy-3-bromomethyl-2,3-dihydro-2,2,4,6,7-pentamethyl-1-benzofuran (see Example 3) and 2.58 g (1 equivalent)of potassium phthalimide in 50 ml of dry dimethylformamide is stirred at 60° C. for 48 hours. Water is added and the product is extracted twice with ethyl ether. The extract is washed with water and brine, and is dried over anhydrous sodium sulfate. After filtration, evaporation of the solvent leaves a residue that is crystallized from ethyl acetate/heptane. The first crop contains free phthalimide, but subsequent crops yield 2,3-dihydro-2,2,4,6,7-pentamethyl-3-phthalimidomethyl-1-benzofuran-5-ol acetate.
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