Dimethylformamide → 5-Bromo-1-methyl-3-nitropyridin-2(1H)-one

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A 1-L round-bottomed flask equipped with a magnetic stirrer was purged with nitrogen and charged with 5-Bromo-3-nitropyridin-2(1H)-one (25.0 g, 114 mmol), anhydrous DMF (500 mL) and potassium carbonate (34.7 g, 251 mmol), and the suspension stirred for 15 min at ambient temperature. After this time, methyl iodide (17.8 g, 126 mmol) was added, and the mixture stirred at room temperature for 16 h. The reaction mixture was then diluted with water (500 mL) and extracted with methylene chloride (3×500 mL). The organic extracts were combined, washed with 10% aqueous lithium chloride (300 mL) and water (300 mL) and dried over sodium sulfate. After removing the drying agent by filtration, the filtrate was evaporated to dryness under reduced pressure. The resulting residue was flash chromatographed eluting with a gradient from 50% to 100% of ethyl acetate in hexanes, and the fractions containing 122a were collected to afford, after concentrating under reduced pressure, an 89% yield (23.6 g) of 122a as a yellow solid: mp 122-123° C.; 1H NMR (300 MHz, CDCl3) δ 8.37 (d, 1H, J=2.7 Hz), 7.26 (s, 1H), 3.68 (s, 3H); MS (ESI+) m/z 234 (M+H).

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