反应详情

5-Methoxyindazole (1.7 g, 11.5 mmol), (Tetrahedron, 1994, 50, 3529), was dissolved in ethylene chloride (35 ml) and cooled in an ice/water bath. Boron tribromide (57.4 ml of a 1M olution 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 pH 8. 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 (1.0 g, 65%) as a brown solid.

1. temperaturecooled in an ice/water bath
2. temperaturere-cooled in an ice/water bath
3. filtrationThe precipitated solid was filtered off
4. customdried under vacuum at 60° C. overnight
5. customThe residue was purified by column chromatography
6. washeluting with methylene chloride/methanol (95/5)