Synthesis
The general procedure for the synthesis of 5-bromo-2-(hydroxymethyl)phenol from 2-hydroxy-4-bromobenzoic acid was as follows: a suspension of 4-bromo-2-hydroxybenzoic acid (8.68 g, 60 mmol) in ether (80 mL) was slowly added dropwise to a suspension of lithium aluminum hydride (LAH, 2.27 g, 60 mmol) in ether (Et2O, 40 mL) with the dropwise acceleration controlled to maintain slight reflux. acceleration was controlled to keep the ether slightly refluxing. After dropwise addition, the reaction mixture was stirred at room temperature overnight. Subsequently, the mixture was cooled to 0 °C and saturated ammonium chloride (NH4Cl) solution (30 mL) was slowly added dropwise to quench the reaction. Next, the mixture was carefully adjusted to acidity with 2N hydrochloric acid (HCl) solution. The mixture was diluted with ethyl acetate (EtOAc) and the supernatant was filtered through a diatomaceous earth pad. The residual precipitate was washed with ethyl acetate (200 mL) and the supernatant was again filtered through diatomaceous earth. This washing process was repeated twice. All filtrates were combined and the organic layer was separated. The ethyl acetate layer was thoroughly washed three times with 1N hydrochloric acid. The organic layer was dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated to afford the target compound 7A as a light yellow solid (6.54 g, 81% yield).1H-NMR (CD3OD) δ 7.31 (d, J=7.8 Hz, 1H), 7.10-7.06 (m, 2H), 5.02 (s, 2H, OH+OH), 4.72 (s. 2H).
References
[1] Patent: WO2009/97567, 2009, A1. Location in patent: Page/Page column 59
[2] Patent: WO2015/86693, 2015, A1. Location in patent: Page/Page column 103
[3] Patent: WO2014/130608, 2014, A1. Location in patent: Page/Page column 128
