To a diethyl ether (50 ml) solution of 1,4-diazabicyclo[2.2.2]octane (1.15 g, 10.3 mmol) was slowly added n-butyllithium (2.6 M hexane solution, 3.95 ml, 10.3 mmol) dropwise at -78 °C. The reaction mixture was stirred at -20°C for 1 hr, then a diethyl ether (30 ml) solution of 3-fluoropyridine (1.00 g, 10.29 mmol) was added dropwise at -78°C. The resulting yellow suspension was stirred at -60°C for 1 hr and subsequently cooled to -78°C and an excess of dry ice was added. The reaction solution was slowly warmed to -10°C over a period of 20 min. The precipitate was collected by filtration and the residue was washed with ether to give pure 3-fluoropyridine-2-carboxylic acid (1.20 g, 8.51 mmol, 83% yield).
