Water → 1H-Indazol-5-ol

HRID 2182411Notes

Reaction equation

HRID 2182411 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.O.C(=O)([O-])O.[Na+]>ClCCl>[OH:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][N:7]=[CH:6]2

Participants

6

Reactant 4

HCID 962WaterHCID 25134Boron tribromideHCID 516892Sodium BicarbonateHCID 133468605-Methoxy-1H-indazole

Product 1

HCID 1014381H-Indazol-5-olYield 83.5%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Conditions

Temperature
0 °C

Procedure

A solution of 5-methoxy-1H-indazole [0.410 g, Reference Example 24(a)] in dichloromethane (7.5 ml) was treated with a solution of boron tribromide in dichloromethane (7.5 ml, 1M). The mixture was then heated to reflux for 4 hours, then cooled to 0° C. and then treated dropwise with water (2 ml). The pH of this mixture was adjusted to 7-8 by addition of 10% aqueous sodium hydrogen carbonate. The mixture was then extracted three times with ethyl acetate. The combined extracts were dried over magnesium sulfate and then evaporated. The residual brown oil was subjected to flash column chromatography on silica eluting with a mixture of ethyl acetate and hexane (1:1, v/v) to give 5-hydroxy-1H-indazole (0.310 g) as a yellow solid. LC-MS (METHOD B): RT=1.96 minutes; 135 (M+H)+.

Workup

  1. temperatureThe mixture was then heated
  2. temperatureto reflux for 4 hours
  3. extractionThe mixture was then extracted three times with ethyl acetate
  4. dry with materialThe combined extracts were dried over magnesium sulfate
  5. customevaporated
  6. additionThe residual brown oil was subjected to flash column chromatography on silica eluting with a mixture of ethyl acetate and hexane (1:1

Sources & evidence

ORD record
ord-0e7560dd1d4e40ab8f615f0158df180b
Source dataset
uspto-grants-2005_05
Patent number
US06897208B2

Reaction notes

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