General procedure for the synthesis of 5-bromo-2-methylpyrimidine from 2-methyl-5-bromopyrimidine-4-carboxylic acid: 5-bromo-2-methylpyrimidine-4-carboxylic acid (350 mg, 1.6 mmol) was dissolved in xylene (5 mL), and the reaction was carried out at reflux for 2 hours. After the reaction was completed, the reaction mixture was cooled to room temperature and directly sampled onto a silica gel column. Gradient elution with petroleum ether and petroleum ether solution containing 5% (v/v) ethyl acetate was carried out sequentially, and the target fraction was collected to give 5-bromo-2-methylpyrimidine (170 mg, 61% yield) as a white solid.LC-MS (m/z): 173 [M + H]+. 1H NMR (400 MHz, DMSO-d6) δ: 2.59 (s, 3H), 8.87 ( s, 2H).
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