Imidazo[1,2-a]pyridine-8-carboxaldehyde (9CI)

Synthesis

DIBAL-H (1M in THF, 20 mL) was added slowly and dropwise to a toluene solution of methyl imidazo[1,2-a]pyridine-8-carboxylate (1.76 g, 10 mmol) at -78 °C. The reaction mixture was stirred continuously at -78 °C for 1 h. The reaction was subsequently quenched with methanol (2 mL) and saturated ammonium chloride solution (50 mL) and gradually warmed to room temperature. The mixture was continued to be stirred at room temperature for 1 hour and then diluted with dichloromethane (60 mL). The aqueous phase was extracted twice with dichloromethane (60 mL). The combined organic layers were dried with anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography with 10% methanol/dichloromethane as eluent to afford imidazo[1,2-a]pyridine-8-carbaldehyde (0.8 g, 55% yield). Low resolution mass spectrometry (LRMS) showed (M+H)+ m/z 147.1.

References

[1] Chemical and Pharmaceutical Bulletin, 1991, vol. 39, # 6, p. 1556 - 1567
[2] Patent: WO2013/102142, 2013, A1. Location in patent: Paragraph 0165