Water → 2-Methyl-3-nitropyridine

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Under nitrogen atmosphere, 47.6 g of 2-chloro-3-nitropyridine was dissolved in 500 mL of tetrahydrofuran, and 150 mL of 2M methylzinc chloride in tetrahydrofuran and 6.9 g of tetrakis(triphenylphosphine)palladium(0) were added, and the reaction solution was stirred at 70° C. for 2 hours. The reaction solution was poured into cold water, extracted with ethyl acetate, washed with water, and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the residue was subjected to column chromatography (n-hexane:ethyl acetate=3:1) to obtain 35.4 g of 2-methyl-3-nitropyridine as a colorless oil. Then 35.4 g of 2-methyl-3-nitropyridine was dissolved in a mixed solution of 300 mL methanol/5 mL triethylamine, added with 5 g of 10% palladium on carbon, and stirred for 6 hours under hydrogen atmosphere and at normal temperature and pressure. The reaction solution was filtered thorough Celite, the solvent was evaporated, and 33.0 g of crudely produced 2-methyl-3-aminopyridine was obtained as a pale brown oil. Next, to 100 mL of a solution of 65 g of crude 3-amino-2-methylpyridine in dichloromethane were added 60 mL of pyridine and 71 mL of acetic anhydride at room temperature and stirred for 3 hours. The reaction solution was added with about 150 mL of silica gel powder, the solvent was evaporated, and the residue was purified by silica gel column chromatography (ethyl acetate:methanol=100:3), to afford 74 g of the title compound as colorless crystals.

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