Sodium hydride (a 60% dispersion in liquid paraffin, 598.8 mg, 14.97 mmol) was washed twice with hexane and then suspended to N,N-dimethylformamide (10 ml). To this suspension was gradually added a solution of 3-(4-isopropylphenyl)-N-(4-methoxybenzyl)-2,2,4,6,7-pentamethyl-2,3-dihydro-1-benzofuran-5-amine (998.9 mg, 2.25 mmol) in N,N-dimethylformamide (30 ml) and the reaction mixture was stirred at 60° C. for 30 minutes. To this mixture was added methyl iodide (2.19 g, 15.45 mmol) and the mixture was stirred at the same temperature for 30 minutes. The reaction solution was cooled down to room temperature and water was added to the solution. The product was extracted with ethyl acetate. The extracts were dried on magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was subjected to column chromatography on silica gel (hexane-ethyl acetate 10:1) to obtain the title compound (69% yield) as an oily mixture of rotamers.
