Bromide ion → 2-Bromo-1-(4-methoxyphenyl)-3-phenylpropan-1-one

To a 500 ml three-necked flask equipped with a thermometer were added 23.0 g (95.7 mmol) 1-(4-methoxy-phenyl)-3-phenyl-propan-1-one prepared in the step 2, 0.30 g (2.25 mmol) anhydrous AlCl3 and 150 ml chloroform, the resulting mixture was agitated, upon the completion of the dissolution, to the mixture was added dropwise a bromide dissolved in 30 ml chloroform maintaining at 5-10° C. in an ice-bath, the dripping was controlled to make the color of bromide disappear quickly. Upon the completion of addition, the mixture was agitated at room temperature for 30 minutes, and then placed into a separating funnel, washed with water, then with saturated aqueous sodium bicarbonate solution, and then with water, dried over anhydrous sodium sulfate, filtrated and concentrated under a reduced pressure to a obtain a crude product, which was subjected to a silica gel column chromatography eluted with petroleum ether/ethyl acetate (13:1) to obtain a 28.7 g colorless liquid product, which was recrystallized with anhydrous ethanol to obtain a white solid in a yield of 93.9%, mp: 57-58□. 1H-NMR (CDCl3, 400 MHz) δ: 3.34 (1H, dd, J=14.28, 7.00 Hz), 3.66 (1H, dd, J=14.28, 7.00 Hz), 3.13 (3H, s, OCH3), 5.29 (1H, t, J=7.32 Hz, CHBr), 6.91 (2H, d, J=9.00 Hz, ArH), 7.18˜7.32 (5H, m, ArH), 7.94 (2H, d, J=9.00 Hz, ArH); ESI-MS m/e (%): 320.8 (M+1, 100), 239.2 (M-Br, 18).