Water → 1H-Indazol-5-ol

HRID 2064667Notes

Reaction equation

HRID 2064667 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-f94256e93b4d4712af52b62086312575
Source dataset
uspto-grants-2012_10
Patent number
US08288425B2

Reaction notes

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