[CH2:1]([O:8][C:9]1[CH:14]=[C:13]([CH2:15][OH:16])[C:12]([OH:17])=[C:11]([CH3:18])[C:10]=1[CH3:19])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[C:20]1(C)[C:21](S(O)(=O)=O)=CC=C[CH:25]=1>COC(OC)(C)C>[CH2:1]([O:8][C:9]1[C:10]([CH3:19])=[C:11]([CH3:18])[C:12]2[O:17][C:20]([CH3:21])([CH3:25])[O:16][CH2:15][C:13]=2[CH:14]=1)[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1A solution of 4-benzyloxy-6-hydroxymethyl-2,3-dimethyl-phenol (86 mg, 0.33 mmol) in dimethoxypropane (10 mL) in the presence of toluene sulfonic acid (7 mg) was stirred at RT for 15 h. It was added 30 mg of anion-exchange resin and stirring was continued for 20 more min. The resin was then filtered off and the solution was concentrated. The crude product was purified on silicagel column chromatography to afford 6-benzyloxy-2,2,7,8-tetramethyl-4H-benzo[1,3]dioxine as a white sticky solid (86 mg). 1H-NMR (CDCl3, 300 MHz) δ (ppm): 7.51-7.35 (m, 5H), 6.45 (s, 1H), 5.02 (s, 2H), 4.85 (s, 2 H), 2.26 (s, 3H), 2.19 (s, 3H), 1.59 (s, 6H); 13C-NMR δ (ppm): 150.6, 143.3, 137.8, 128.5, 127.8, 126.3, 125.8, 115.9, 105.4, 99.1, 70.9, 61.1, 24.9, 12.2, 11.5.
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