[OH:1][C:2]1[C:3]([CH3:17])=[C:4]2[C:9](=[C:10]([CH3:13])[C:11]=1[CH3:12])[O:8][C:7](=[O:14])[CH2:6][C:5]2([CH3:16])[CH3:15].CC(C)=[O:20].O.C1C(=O)N(Br)C(=O)C1>C(#N)C>[CH3:15][C:5]([C:4]1[C:9](=[O:8])[C:10]([CH3:13])=[C:11]([CH3:12])[C:2](=[O:1])[C:3]=1[CH3:17])([CH3:16])[CH2:6][C:7]([OH:20])=[O:14]To the solution of 6-hydroxy-4,4,5,7,8-pentamethylchroman-2-one (15 g, 0.064 mol) in a mixture of acetonitrile (600 ml), acetone (50 ml) and water (300 ml), NBS (11.4 g, 0.064 mol) was added. The resultant mixture was stirred for 30 minutes at room temperature. After removing most of the organic solvent, the yellow solid was collected by filtration, washed by water and dried over vacuum to afford a yield of 96%. 1H NMR (300 MHz, CD2Cl2) δ 3.0 (s, 2H, CH2), 2.13 (s, 3H, CH3), 1.94 (s, 3H, CH3), 1.92 (s, 3H, CH3), 1.44 (s, 6H, CH3); MS (m/e): 251 (M+).
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