Synthesis
General procedure for the synthesis of 1-(4-bromo-2-hydroxyphenyl)ethanone from phenyl 3-bromoacetate: In a round-bottomed flask equipped with a reflux condenser, a nitrogen inlet, and a sodium hydroxide solution, aluminum chloride (36 g, 270 mmol) was slowly added to intermediate 9A (32.0 g, 149 mmol) to absorb the HCl gas generated. Water was generated during the reaction. The reaction flask was heated in an oil bath at 120°C. The reaction mixture gradually became fluid and was then slowly warmed to 165°C over a period of 1 hour and held at this temperature for 1 hour. Upon completion of the reaction, the mixture was cooled to room temperature. Approximately 200 mL of dichloromethane was added to the solid reaction mixture to form a slurry. The slurry was slowly poured into ice, a process that needed to be repeated several times to ensure complete treatment of the reaction mixture. The dichloromethane/water mixture was stirred until both phases became fairly clear, followed by phase separation. The organic phase was washed with brine, dried over anhydrous magnesium sulfate and finally concentrated under vacuum to give Intermediate 9B (30.14 g, 140 mmol, 94% yield) as a dark red oil. Mass spectrum (ESI) m/z 213,215.3 (M + H)+. The purity of the product was about 90%.
References
[1] Patent: US2009/202478, 2009, A1
[2] Patent: WO2007/37187, 2007, A1. Location in patent: Page/Page column 137
[3] Patent: WO2008/79836, 2008, A2. Location in patent: Page/Page column 96-97
[4] Synthesis (Germany), 2017, vol. 49, # 9, p. 1983 - 1992
[5] MedChemComm, 2013, vol. 4, # 11, p. 1434 - 1438
