Tert-Butyl (3R)-3-aminopiperidine-1-carboxylate (0.51 g, 2.54 mmol) and cesium fluoride (0.83 g, 5.46 mmol) were added to a stirred solution of 3-(6-chloropyrazin-2-yl)pyrazolo[1,5-a]pyridine (Preparation 27b, 0.42 g, 1.82 mmol) in dimethylsulfoxide (20 mL). The resulting mixture was stirred at 100° C. for 22 h before being poured onto 50 mL of water. The resultant suspension was extracted with ethyl acetate (×2) and the combined organic layers were dried over magnesium sulphate, filtered and evaporated to dryness. The crude product was purified by flash chromatography (3:7 to 7:3 ethyl acetate/hexane) to give the title compound (0.244 g, 34%) as a yellowish foam.
