c) Synthesis of 5-bromo-2,4-dimethylpyrimidine. A mixture of 5-bromo-4-chloro-2,6-dimethylpyrimidine (2.73 g, 12.33 mmol), 4-methylbenzenesulfonylhydrazine (4.19 mL, 37.0 mmol) and chloroform (40 mL) was heated and refluxed for 16 hr at 90 °C. Upon completion of the reaction, the mixture was cooled to room temperature, the solid product was collected by filtration and washed with chloroform. The resulting solid (4.75 g) was confirmed as the expected intermediate by LC-MS analysis. Subsequently, the intermediate was mixed with 0.94 M aqueous sodium carbonate solution (40 mL, 37.7 mmol) and heated and stirred at 90 °C for 1.5 hours. After the reaction mixture was cooled, it was extracted three times with ethyl acetate, the organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to afford the title compound, 5-bromo-2,4-dimethylpyrimidine (1.17 g, 51% yield), as a tan oil, which was crystallized after standing. LC-MS (ES+) m/z: 187 [M + H]+.
