138888-98-9

356560-80-0

General procedure: N'-(5-bromo-2-pyridinyl)-N,N-dimethylformamidine (4 g, 17.54 mmol, 1.00 eq.) was dissolved in methanol (40 mL) under nitrogen protection and cooled to 0 °C. Subsequently, pyridine (4 mL, 2.00 eq.) and aminoxysulfonic acid (3.6 g, 31.83 mmol, 1.30 eq.) were added sequentially. The reaction mixture was stirred at room temperature for 12 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The residue was diluted with ethyl acetate (150 mL) and washed sequentially with saturated aqueous sodium carbonate solution (50 mL x 1) and water (50 mL x 2). The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with the eluent of ethyl acetate/hexane (1:1) to afford 6-bromo-[1,2,4]triazolo[1,5-A]pyridine 2.5 g (72% yield) as a solid. LC/MS (Method D, ESI): retention time = 1.1 min, m/z = 198.0 [M+H]+.