Dimethyl Sulfoxide → 1H-Pyrazolo[4,3-b]pyridine-5-carboxaldehyde

Participants

Reaction Steps

1H-pyrazolo[4,3-b]pyridine-5-methanol (240 mg, 1.61 mmol) was dissolved in DCM (24 mL) at rt, and DMSO (5.71 mL, 80.45 mmol) and NEt3 (1.12 mL, 8.05 mmol) were added. After 10 min, SO3-pyridine was added, and the mixture was stirred at rt for ca. 1.5 hr. The reaction was quenched with sat. NH4Cl solution, stirred for 10 min, then extracted with DCM, washed with water and with brine, and dried with Na2SO4. The crude product (orange oil) was purified by a short manual flash column (hex/EtOAc 1:1) to afford 1H-pyrazolo[4,3-b]pyridine-5-carboxaldehyde (62 mg, 26.2%) as a white solid.

Provenance & Evidence