Synthesis
General procedure for the synthesis of 4-bromo-6-methylpyridin-2-ol from 2,4-dihydroxy-6-methylpyridine: 4-hydroxy-6-methylpyridin-2(1H)-one (500 mg, 4.00 mmol) was mixed with phosphoribromide (881 mg, 3.07 mmol) in DMF (1.8 mL). The reaction mixture was heated to 110 °C and maintained for 5 min, then DMF (1.8 mL) was added additionally and the reaction was continued at 110 °C for 1 hour. Upon completion of the reaction, it was cooled to room temperature and the reaction was quenched by slow addition of ice water, followed by adjusting the pH with solid sodium bicarbonate to 7. The precipitate was collected by filtration, washed with cold water, and dried in air to afford the target product 4-bromo-6-methylpyridin-2-ol (520 mg, 2.77 mmol, 90% yield).
References
[1] Patent: WO2016/196644, 2016, A1. Location in patent: Paragraph 574; 575
[2] Patent: WO2018/102452, 2018, A2. Location in patent: Paragraph 558; 559
