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B) General procedure for synthesizing methyl 5-bromo-2-hydroxy-4-methylbenzoate: sulfuric acid (6.77 mL) was added slowly and dropwise to a solution of methanol (200 mL) containing 5-bromo-2-hydroxy-4-methylbenzoic acid (6.78 g). The reaction mixture was stirred continuously at 70 °C overnight. Upon completion of the reaction, the reaction mixture was concentrated by distillation under reduced pressure. Subsequently, the residue was neutralized with saturated aqueous sodium bicarbonate solution and extracted with ethyl acetate under ice bath cooling conditions. The organic layers were combined, washed sequentially with water and saturated brine, and then dried over anhydrous sodium sulfate. After drying, the solvent was removed by evaporation under reduced pressure. Finally, the residue was purified using silica gel column chromatography (eluent: ethyl acetate/hexane) to afford the target product methyl 5-bromo-2-hydroxy-4-methylbenzoate (6.56 g). The result of mass spectrometry analysis: [M-H]+ 243.0.

[1] Patent: WO2018/24224, 2018, A1. Location in patent: Page/Page column 80; 81; 82
[2] Patent: WO2015/163485, 2015, A1. Location in patent: Paragraph 0350
[3] Patent: WO2016/208775, 2016, A1. Location in patent: Paragraph 0394