3-Bromophenacyl bromide (20.9 g) was dissolved in dichloromethane (400 mL). After ice-cooling the solution, N,N-diisopropylethylamine (14.3 mL) and allyl(2,4-dimethoxybenzyl)amine (18.7 g) were dissolved in dichloromethane (50 mL) and added dropwise. The reaction solution was gradually warmed to room temperature while dipping in an ice water bath, and stirred for about 20 hours. Chloroform, a saturated sodium bicarbonate solution and a saturated sodium chloride solution were sequentially added to the reaction solution, and the organic layer was separated. The organic layer was dried over anhydrous magnesium sulfate (2 g). The drying agent was removed by filtration and then the filtrate was concentrated under reduced pressure to obtain a crude product. The product was subjected to silica gel column chromatography to obtain the title compound (29.88 g).
