N-bromobutanimide → 3-bromo-6-(1-methyl-1H-pyrazol-4-yl)pyrazolo[1,5-a]pyridin-4-ol

Participants

Reaction Steps

6-(1-methyl-1H-pyrazol-4-yl)pyrazolo[1,5-a]pyridin-4-ol (75.0 mg, 0.350 mmol) was suspended in acetonitrile (4 ml). N-bromosuccinimide (68.5 mg, 0.385 mmol) was added and the mixture was allowed to stir. After 30 minutes, additional N-bromosuccinimide (6.9 mg, 0.039 mmol) was added and the mixture was allowed to stir for 1 h. The reaction mixture was diluted in dichloromethane, washed with water and 1 N aqueous sodium hydroxide. The pH of the combined aqueous layers was adjusted to pH 7 with 6 N HCl, then the aqueous layers were extracted with ethyl acetate (2×) and the combined organic layers were dried over sodium sulfate, filtered and concentrated. The residue was purified by column chromatography on silica gel (methanol/dichloromethane gradient) to afford 3-bromo-6-(1-methyl-1H-pyrazol-4-yl)pyrazolo[1,5-a]pyridin-4-ol.

Provenance & Evidence