General procedure for the synthesis of 5-bromo-2-chloro-4-methylpyrimidine from 5-bromo-2,4-dichloropyrimidine and methylmagnesium bromide: A mixture of 5-bromo-2,4-dichloropyrimidine (0.4 g) and iron(III) acetylacetonate (0.062 g) in tetrahydrofuran (10 mL) was cooled to 0 °C. Methylmagnesium bromide (3M solution in diethyl ether, 0.76 mL) was added dropwise and the mixture was stirred at 0°C for 2 hours. Upon completion of the reaction, the reaction was quenched by the addition of saturated ammonium chloride solution, followed by extraction of the mixture with ethyl acetate (2 x 20 mL). The organic phases were combined, dried with anhydrous sodium sulfate and concentrated under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography using gradient elution with ethyl acetate and n-heptane to afford the target compound 5-bromo-2-chloro-4-methylpyrimidine (0.220 g, 60% yield) as a white solid.1H NMR (300 MHz, CDCl3) δ 8.52 (s,1H), 2.57 (s,3H).
