Water → 5-nitro-1H-indole-3-carboxylic acid

HRID 2165536Notes

Reaction equation

HRID 2165536 reaction equation
FC(F)(F)C([O:5][C:6](=[O:11])[C:7](F)(F)F)=O.[N+:14]([C:17]1[CH:18]=[C:19]2[C:23](=[CH:24][CH:25]=1)[NH:22][CH:21]=C2)([O-:16])=[O:15].O>CN(C)C=O>[N+:14]([C:17]1[CH:25]=[C:24]2[C:23](=[CH:19][CH:18]=1)[NH:22][CH:21]=[C:7]2[C:6]([OH:5])=[O:11])([O-:16])=[O:15]

Participants

5

Reactant 3

HCID 962WaterHCID 9845Trifluoroacetic anhydrideHCID 225235-Nitroindole

Product 1

HCID 2481365-nitro-1H-indole-3-carboxylic acid

Reagents, catalysts & solvents 1

HCID 6228DimethylformamideSolvent

Procedure

Trifluoroacetic anhydride (21.37 g) was added dropwise to a chilled solution of 5-nitro-1H-indole (15.0 g) in dry dimethylformamide (150 ml) under a dry N2 atmosphere. The solution was allowed to warm to room temperature, and was then heated at reflux for 24 hours. The reaction mixture was cooled and poured into water (500 ml) and the resulting dark brown precipitate was filtered, suspended in water (200 ml) containing sodium hydroxide (50.0 g), and heated at reflux for 3 hours. The dark brown solution was cooled to room temperature, extracted with ether (4×100 ml), acidified to pH2 and the title compound filtered and dried (19 g), m.p. 256°-258° C. δH (360 MHz, DMSO-d6) 7.71 (1H, d, J=7.2 Hz, H-7), 8.9 (1H, dd, J=7.2, 1.0 Hz), 8.27 (1H, s, H-2), 8.89 (1H, d, J= 1.0 Hz, H-4); m/z 206 (M+, 70), 163 (10), 138 (20), 123 (100, 106 (15), 81 (10%).

Workup

  1. temperaturewas then heated
  2. temperatureat reflux for 24 hours
  3. temperatureThe reaction mixture was cooled
  4. filtrationthe resulting dark brown precipitate was filtered
  5. additioncontaining sodium hydroxide (50.0 g)
  6. temperatureheated
  7. temperatureat reflux for 3 hours
  8. temperatureThe dark brown solution was cooled to room temperature
  9. extractionextracted with ether (4×100 ml)
  10. filtrationthe title compound filtered
  11. customdried (19 g), m.p. 256°-258° C. δH (360 MHz, DMSO-d6) 7.71 (1H, d, J=7.2 Hz, H-7), 8.9 (1H, dd, J=7.2, 1.0 Hz), 8.27 (1H, s, H-2), 8.89 (1H, d, J= 1.0 Hz, H-4)

Sources & evidence

ORD record
ord-845001207703407daae430ab57f5e2b9
Source dataset
uspto-grants-1990_07
Patent number
US04940703

Reaction notes

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