Synthesis
1. Methylation: 5-chloro-2-hydroxyacetophenone (17.0 g, 100 mmol), potassium carbonate (15.1 g, 109 mmol) and iodomethane (12.5 mL, 200 mmol) are dissolved in DMF in a sealed container and stirred at room temperature overnight. Upon completion of the reaction, the DMF was evaporated under reduced pressure and the residue was partitioned with water and ethyl acetate. The organic phases were combined, dried with anhydrous sodium sulfate and concentrated to give the crude product. Purification by silica gel column chromatography (eluent: ethyl acetate/hexane) afforded 1-(5-chloro-2-methoxyphenyl)ethanone (17.1 g, 93% yield). Mass spectra (electrospray ionization): (M + 1)+ m/z 185.1, 187.1.
2. Bromination Reaction: 1-(5-chloro-2-methoxyphenyl)ethanone (8.5 g, 46.2 mmol) was dissolved in chloroform (40 mL) and slowly added to a preheated ethyl acetate slurry (150 mL) of copper(II) bromide (20.6 g, 92.4 mmol). The reaction mixture was heated to reflux and maintained for about 1 to 3 hours. After cooling, it was filtered and the filtrate was concentrated to give the crude product. Purification by silica gel column chromatography (eluent: dichloromethane) afforded 2-bromo-1-(5-chloro-2-methoxyphenyl)ethanone (12.0 g, 99% yield). MS (electrospray ionization): (M + 1)+ m/z 185.1, 187.1.
References
[1] Patent: WO2005/19184, 2005, A1. Location in patent: Page/Page column 74
[2] Bioorganic and Medicinal Chemistry Letters, 2007, vol. 17, # 5, p. 1291 - 1295
[3] Patent: WO2005/19184, 2005, A1. Location in patent: Page/Page column 43-44
[4] Chemical Communications, 2014, vol. 50, # 51, p. 6726 - 6728
[5] Patent: WO2016/16370, 2016, A1. Location in patent: Page/Page column 44
