Sodium Hydroxide → 1H-Indazol-5-ol
Reaction equation
C[O:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][N:7]=[CH:6]2.B(Br)(Br)Br.[OH-].[Na+]>C(Cl)CCl.C(Cl)Cl>[OH:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][N:7]=[CH:6]2Participants
6
C[O:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][N:7]=[CH:6]2.B(Br)(Br)Br.[OH-].[Na+]>C(Cl)CCl.C(Cl)Cl>[OH:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][N:7]=[CH:6]25-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.
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