Synthesis
Example-2; Synthesis of 2-bromo-1-(4-fluorophenyl)-2-phenylethanone; In a four-necked round-bottomed flask equipped with a mechanical stirring bar, a pressure equalizing funnel and a CaCl2 drying tube, dichloromethane (1 L) was added. 100 g (0.466 mol) of 1-(4-fluorophenyl)-2-phenylethanone was added to the flask and stirred for 5 min until completely dissolved to form a clarified solution. Subsequently, 2 mL of a 30% hydrobromic acid solution of acetic acid was added, followed by the slow dropwise addition of bromine (73 g, 0.456 mol) dissolved in 200 mL of a cold solution of dichloromethane at 26 ± 2 °C. The rate of the dropwise addition needs to be controlled to ensure that the bromine reacts immediately, which can be observed by the color change of the reaction mixture. After the dropwise addition, the reaction mixture was cooled to 19±1°C, 5% aqueous sodium sulfite solution (200 mL) was added, and stirred at 21.5±3.5°C for about 1 hour. After the reaction was completed, the organic layer was separated and washed twice with 5% aqueous sodium sulfite solution (2 x 200 mL) repeatedly. Next, the organic layer was stirred with 5% aqueous sodium bicarbonate solution (200 mL) at 21.5 ± 3.5 °C for about 1 h, after which the organic layer was separated. Finally, the organic layer was washed with 5% aqueous sodium chloride solution (200 mL) and separated. The organic layer was dried over anhydrous sodium sulfate and filtered, the dichloromethane was removed by distillation, and the resulting slurry was converted to a light orange solid after standing. The final product was 129 g in 94.8% yield.
References
[1] Journal of Medicinal Chemistry, 2014, vol. 57, # 15, p. 6479 - 6494
[2] Patent: WO2012/143933, 2012, A1. Location in patent: Page/Page column 13-14
[3] Synthetic Communications, 2016, vol. 46, # 2, p. 165 - 168
[4] Patent: CN106397296, 2017, A. Location in patent: Paragraph 0018; 0021; 0024; 0027; 0030; 0033; 0036; 0039
[5] Tetrahedron, 2017, vol. 73, # 34, p. 5207 - 5213
