Hydrogen Bromide → 6-Bromo-4-methoxypyrazolo[1,5-a]pyridine

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Reaction Conditions

Reaction Steps

A solution of ethyl 6-bromo-4-methoxylpyrazolo[1,5-a]pyridine-3-carboxylate (15, 5.2 g, 18.24 mmol) in HBr (100 ml, 884 mmol) was heated to 100° C. for 1 hour. After cooling to 0° C., 1M NaOH (182 ml, 912 mmol) was used to neutralize the solution. The reaction mixture was diluted in ethyl acetate, washed with saturated aqueous sodium hydroxide (1N) and brine then dried over Na2SO4. After filtration and concentration, the residue was purified by column chromatography (0-35% EtOAc in hexanes, linear gradient) to give 6-bromo-4-methoxypyrazolo[1,5-a]pyridine (16, 2.475 g, 10.90 mmol, 60% yield). MS APCI: [M+H]+ m/z 228.1.

Provenance & Evidence