Nitric Acid → Methyl 2-amino-5-nitronicotinate

2-Amino-nicotinic acid methyl ester (1.00 g, 6.57 mmol) described in Preparation Example A-2 was dissolved at 0° C. in a mixed solution of nitric acid (0.7 mL) and sulfuric acid (2.6 mL), which was stirred at 0° C. for 40 minute and at room temperature for 19 hours, then, further stirred at 70° C. for 4 hours. A saturated aqueous solution of sodium bicarbonate was added to the reaction solution at 0° C., which was extracted with ethyl acetate and tetrahydrofuran, the organic layer was washed with brine and dried over anhydrous magnesium sulfate. The solvent was evaporated in vacuo. Methanol was added to the residue, the precipitated solid was filtered to obtain the title compound (459 mg, 2.33 mmol, 35%) as a white solid.