To a solution of tert-butyl 4-(3,5-difluoro-2-(trifluoromethyl)phenyl)piperidine-1-carboxylate (0.246 g, 0.675 mmol) in dichloromethane (5 mL) was added HCl (2 M in ether, 10 mL). The mixture was stirred for 6 h and evaporated to afford a solid that was dissolved in DMF (4 mL). In a separate flask, to a solution of ethyl 6-bromo-[1,2,4]triazolo[4,3-a]pyridine-3-carboxylate (0.182 g, 0.675 mmol) in THF (5 mL) was added a solution of lithium hydroxide hydrate (0.028 g, 0.675 mmol) in water (2 mL). The mixture was stirred for 20 min, acidified with 2 N HCl to pH 6 and evaporated to dryness. To this residue were added benzotriazole-1-yl-oxytris(dimethylamino)phosphonium hexafluorophosphate (0.448 g, 1.01 mmol), N,N-diisopropylethylamine (0.349 g, 2.70 mmol), and the DMF solution obtained from the first reaction. The mixture was stirred at ambient temperature for 16 h and poured into water. The mixture was extracted with ethyl acetate and the organic layer was washed with brine for three times, dried (Na2SO4), filtered, and concentrated under reduced pressure. The resulting residue was chromatographed over silica gel (0-60% EtOAc in hexanes) to give (6-bromo-[1,2,4]triazolo[4,3-a]pyridin-3-yl)(4-(3,5-difluoro-2-(trifluoromethyl)phenyl)piperidin-1-yl)methanone as an off-white solid (0.115 g, 34%): 1H NMR (300 MHz, CDCl3) δ9.37 (m, 1H), 7.79 (dd, J=9.6, 0.9 Hz, 1H), 7.50 (dd, J=9.6, 1.7 Hz, 1H), 6.96 (d, J=9.7 Hz, 1H), 6.84-6.77 (m, 1H), 5.77-5.72 (m, 1H), 5.00-4.95 (m, 1H), 3.44-3.29 (m, 2H), 3.01-2.92 (m, 1H), 2.01-1.69 (m, 4H); MS (ESI+) m/z 489 [M+H]+.
