A solution of sodium nitrite (20 g, 288 mmol) in water (40 mL) was added dropwise to a stirred mixture of 3-amino-4-nitropyridine (40 g, 288 mmol) in 34% fluoboric acid (140 mL). During the addition, the temperature was maintained between -8C and -2C. After 0.5 h, the suspension was filtered and the solids were washed with 34% fluoboric acid (35 mL), ether (80 mL) and dried under high vacuum at room temperature for 12 h. The dried solids were decomposed by heating to 120C. The solids were then dried over a period of time. After decomposition, the remaining oil was treated with a 10% sodium bicarbonate (80 mL) solution and the mixture was extracted with dichloromethane. The combined extracts were dried with sodium sulfate, filtered and the solvent removed under reduced pressure to give the title compound as a light yellow solid.
