A 2M aqueous sodium hydroxide solution (1.91 mL, 3.8 mmol) was slowly added to a stirring solution of ethyl 5-bromo-6-methylnicotinate (Preparation 47c, 0.41 g, 1.7 mmol) in ethanol (14 mL) at room temperature. After 3 hours of reaction, the solvent was removed by evaporation under reduced pressure. To the residue, an appropriate amount of water was added and the pH was adjusted to 4-5 with concentrated hydrochloric acid. subsequently, the mixture was extracted with ethyl acetate. The organic layer was separated, washed with deionized water, dried over anhydrous magnesium sulfate, and finally concentrated under reduced pressure to afford the target product 5-bromo-6-methylnicotinic acid (0.16 g, 43% yield) as a white solid.LRMS (m/z): 216/218 (M + 1)+.
