[CH3:1][C:2]1([CH3:15])[CH2:11][C:10]([CH3:13])([CH3:12])[C:9]2[C:4](=[CH:5][C:6]([CH3:14])=[CH:7][CH:8]=2)[O:3]1.[C:16](Cl)(=[O:18])[CH3:17].[Cl-].[Al+3].[Cl-].[Cl-].Cl>[N+](C)([O-])=O.CCOCC.O>[CH3:1][C:2]1([CH3:15])[CH2:11][C:10]([CH3:13])([CH3:12])[C:9]2[C:4](=[CH:5][C:6]([CH3:14])=[C:7]([C:16](=[O:18])[CH3:17])[CH:8]=2)[O:3]1To an ice-bath cooled solution of 1.96 g (9.6 mmol) of 2,2,4,4,7-pentamethyl-chroman (Compound 89) in 30 ml of nitromethane was added under argon 1.059 g (13.5 mmol) of acetyl chloride followed by 1.9 g (14.3 mmol) of aluminum chloride. The reaction mixture was stirred at room temperature for 14 h and then cooled in an ice-bath and treated with 25 ml of conc. HCl. The mixture was warmed to room temperature and diluted with ether and water. The organic layer was separated and the aqueous layer extracted with ether. The organic extracts were combined and washed successively with water, saturated NaHCO3 solution, water again, and saturated NaCl solution, and then dried (MgSO4). The solvent was removed in vacuo and the residue was purified by flash chromatography (silica; 5% ethyl acetate in hexanes) to give the title compound as a pale yellow oil. PMR (CDCl3): 1.36 (6H, s), 1.37 (6H, s), 1.86 (2H, s), 2.49 (3H, s), 2.56 (3H, s), 6.65 (1H, s), 7.74 (1H, s).
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