Synthesis
A suspension of 4-aminopyridine (7.06 g, 75.1 mmol) in 40 mL of anhydrous dichloromethane was stirred at -78C for 15 min.
minutes and added to anhydrous HF (31.2 g, 1.6 ) that had been cooled to -78C in a polyethylene vial.
mol). The reaction mixture was allowed to warm to -5C and NaNO2 was added in batches over 10 min.
(6.22 g, 90.1 mmol) while maintaining the temperature between -5 and 0C. The mixture was allowed to warm to room temperature and then heated to 40-50C for 1.5
hours. Dichloromethane (50 mL) was added. After cooling to -10C, adjust pH to 10 by dropwise addition of 30% aqueous NH4OH over 10 min. filter to break emulsion and extract with dichloromethane.
After drying on silica gel, HCl gas was bubbled through the solution. The solvent was evaporated in vacuum to give 4.9 g (37.1 mmol, 50%) of a pale yellow salt.
