Hydrochloric Acid → 6-Hydroxy-1H-indole-2-carboxylic acid

HRID 230563Notes

Reaction equation

HRID 230563 reaction equation
B(Br)(Br)Br.C[O:6][C:7]1[CH:15]=[C:14]2[C:10]([CH:11]=[C:12]([C:16]([O:18]C)=[O:17])[NH:13]2)=[CH:9][CH:8]=1.Cl>C(Cl)Cl>[OH:6][C:7]1[CH:15]=[C:14]2[C:10]([CH:11]=[C:12]([C:16]([OH:18])=[O:17])[NH:13]2)=[CH:9][CH:8]=1

Participants

5

Reactant 3

HCID 313Hydrochloric AcidHCID 25134Boron tribromide2×HCID 688173Methyl-6-methoxy-2-indolecarboxylate

Product 1

HCID 223501916-Hydroxy-1H-indole-2-carboxylic acidYield 74%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent3×

Conditions

Temperature
0 °C

Procedure

146 ml (146 mmol) of 1M boron tribromide in methylene chloride are added slowly, at 0° C., to a solution of 10 g (48.73 mmol) of methyl 6-methoxy-2-indole carboxylate in 500 ml of methylene chloride. The reaction medium is stirred at 0° C. for 1 h and at ambient temperature for 2 h. The reaction medium is cooled to 0° C. and 100 ml (100 mmol) of 1M boron tribromide in methylene chloride are added slowly, at 0° C. The reaction is stirred at 0° C. for 1 h and at ambient temperature for 16 h. The reaction medium is then cooled to approximately 0° C. and a 1N hydrochloric acid solution (247 ml) is added slowly with stirring. The mixture obtained is filtered over sintered glass. The organic phase (methylene chloride) of the filtrate is separated and the aqueous phase is then acidified with 5N hydrochloric acid and extracted with ethyl acetate. The organic phase (ethyl acetate) is dried over anhydrous magnesium sulfate, filtered, and concentrated to dryness under reduced pressure, to give 6.39 g of 6-hydroxy-1H-indole-2-carboxylic acid in the form of a brown solid.

Workup

  1. temperatureThe reaction medium is cooled to 0° C.
  2. stirringThe reaction is stirred at 0° C. for 1 h and at ambient temperature for 16 h
  3. temperatureThe reaction medium is then cooled to approximately 0° C.
  4. stirringwith stirring
  5. customThe mixture obtained
  6. filtrationis filtered over sintered glass
  7. customThe organic phase (methylene chloride) of the filtrate is separated
  8. extractionextracted with ethyl acetate
  9. dry with materialThe organic phase (ethyl acetate) is dried over anhydrous magnesium sulfate
  10. filtrationfiltered
  11. concentrationconcentrated to dryness under reduced pressure

Sources & evidence

ORD record
ord-a3e8036811a04bf69217692e1b31970b
Source dataset
uspto-grants-2009_07
Patent number
US07566736B2

Reaction notes

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