Sodium Hydroxide → 1H-Indazol-5-ol

Participants

Reaction Steps

5-Methoxyindazole (1.7 g, 11.5 mmol), (Tetrahedron, 1994, 50, 3529), was dissolved in methylene chloride (35 ml) and cooled in an ice/water bath. Boron tribromide (57.4 ml of a 1M solution in methylene chloride, 57.4 mmol) was added over 10 minutes and then the mixture allowed to warm to ambient temperature. The mixture was stirred for 2 hours and then re-cooled in an ice/water bath. 2N Sodium hydroxide was slowly added until pH8. The precipitated solid was filtered off and dried under vacuum at 60° C. overnight. The residue was purified by column chromatography eluting with methylene chloride/methanol (95/5) to give 5-hydroxyindazole (11.0 g, 65%) as a brown solid.

Provenance & Evidence