ChemicalBook CAS DataBase List 1H-Indazol-5-ol

1H-Indazol-5-ol synthesis

7synthesis methods

Product Name:1H-Indazol-5-ol
CAS Number:15579-15-4
Molecular formula:C7H6N2O
Molecular Weight:134.14

94444-96-9

15579-15-4

General procedure for the synthesis of 1H-indazol-5-ol using 5-methoxy-1H-indazole as starting material: a dichloromethane solution of boron tribromide (18.5 mL, 18.5 mmol) was slowly added dropwise to a solution of 5-methoxy-1H-indazole (1.24 g, 8.40 mmol) in dichloromethane (84 mL) at 0 °C. After the dropwise addition was completed, the reaction mixture was warmed to room temperature and stirred continuously for 10 hours. Upon completion of the reaction, the reaction solution was poured into an ice water bath and subsequently extracted with ethyl acetate. The organic phases were combined and washed sequentially with saturated aqueous sodium bicarbonate solution and saturated aqueous sodium chloride solution. The organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. The resulting crude product was purified by silica gel column chromatography (eluent: chloroform/methanol=96/4, v/v) to afford 1H-indazol-5-ol (877 mg, 71% yield) as a white solid. The structure of the product was confirmed by 1H-NMR (DMSO-d6): δ 6.88 (1H, dd, J = 8.8, 2.2 Hz), 6.96 (1H, d, J = 2.2 Hz), 7.34 (1H, d, J = 8.8 Hz), 7.84 (1H, s).

94444-96-9 Synthesis

94444-96-9
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15579-15-4
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Yield: 71%

Reaction Conditions:

with boron tribromide in dichloromethane at 20; for 10 h;

Steps:

4.b Reference Example 4; Synthesis of 1H-indazol-5-ol; (b) Synthesis of 1H-indazol-5-ol
A methylene chloride solution of boron tribromide (18.5 ml, 18.5 mmol) was added to a solution of 5-methoxy-1H-indazole (1.24 g, 8.40 mmol) in methylene chloride (84 ml) at 0°C and stirred at room temperature for 10 hours. Then, water was poured into the reaction solution in an ice-water bath, followed by extraction with ethyl acetate. The organic layer was washed with a saturated aqueous sodium hydrogencarbonate solution and then a saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, and distilled under reduced pressure to remove the solvent, and the resulting residue was purified by a silica gel column chromatography (eluent: chloroform/methanol = 96/4) to obtain 1H-indazol-5-ol (877 mg, 71%).1H-NMR (DMSO-d6) δ; 6.88 (1H, dd, J=8.8, 2.2Hz), 6.96 (1H, d, J=2.2Hz), 7.34 (1H, d, J=8.8Hz), 7.84 (1H, s).

References:

Sumitomo Pharmaceuticals Company, Limited EP1403255, 2004, A1 Location in patent:Page 44