n a 100-mL PFA made reactor equipped with a reflux condenser, 4-aminopyridine (470 mg, 5mmol) was added to HF/Pyridine (70% HF, 10 mL) at 0oC. The mixture was allowed to stand at room temperature until 4-aminopyridine was completely dissolved. After cooling down to –78oC, NaNO2 (380 mg, 5.5 mmol) was added to a solution of 4-aminopyridine in HF, the stirred solution was allowed to stand at 0oC for 30 min and then stand at 60oC for 15-30 min. By quenching the resultant solution with ice water, followed by the neutralization with cold saturated NaHCO3, the resulting mixture was extracted with CH2C12, the combined organic phase was dried over MgSO4, and evaporated under reduced pressure to give the crude product, which was distilled to give the desired product (460 mg, 95%).