[1,2,4]Triazolo[1,5-a]pyridine-6-carboxaldehyde (9CI)

68-12-2

614750-81-1

General procedure for the synthesis of [1,2,4]triazolo[1,5-a]pyridine-6-carbaldehyde from N,N-dimethylformamide: (a) A solution of 6-iodo-[1,2,4]triazolo[1,5-a]pyridine (5.0 g) was prepared by dissolving 2-amino-5-iodopyridine (20 mmol) in anhydrous THF (300 mL) at 0 °C and slowly adding THF solution of isopropylmagnesium bromide (1M, 31 mL, 31 mmol). The resulting emulsion suspension was stirred at 0 °C for 1 h. DMF (6 mL, 50 mmol) was added. The suspension was allowed to warm up to room temperature and stirring was continued for 4 hours. Subsequently, 100 mL of water was added at room temperature and stirred for 1 hour. The reaction mixture was extracted with diethyl ether and washed with saturated Na2CO3 solution. The organic phase was dried with MgSO4 and concentrated. The residue was purified by silica gel short column chromatography using EtOAc as eluent to afford [1,2,4]triazolo[1,5-a]pyridine-6-carboxaldehyde as a light yellow solid (3 g, 100% yield). ESI-MS m/z: 148.0 [M+H]+. 1H NMR (CDCl3, 300MHz) δ: 10.03 (s, 1H), 9.10 (s, 1H), 8.49 (s, 1H), 8.02 (d, 1H), 7.82 (d, 1H).