Citric Acid → 4,6-dicyano-1H-indole-2-carboxylic acid

HRID 62649Notes

Reaction equation

HRID 62649 reaction equation
[C:1]([C:3]1[CH:11]=[C:10]([C:12]#[N:13])[CH:9]=[C:8]2[C:4]=1[CH:5]=[C:6]([C:14]([O:16]CC)=[O:15])[NH:7]2)#[N:2].C(O)(=O)CC(CC(O)=O)(C(O)=O)O>C(O)C.O>[C:1]([C:3]1[CH:11]=[C:10]([C:12]#[N:13])[CH:9]=[C:8]2[C:4]=1[CH:5]=[C:6]([C:14]([OH:16])=[O:15])[NH:7]2)#[N:2]

Participants

5

Reactant 2

HCID 311Citric AcidHCID 89995321ethyl 4,6-dicyano-1H-indole-2-carboxylate

Product 1

HCID 899953204,6-dicyano-1H-indole-2-carboxylic acidYield 57%

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 962WaterSolvent

Procedure

To a stirred solution of ethyl 4,6-dicyano-1H-indole-2-carboxylate (I-2a: 500 mg, 2.09 mmol) in ethanol (10 mL) was added LiOHH2O (176 mg, 4.18 mmol) and heated to reflux for 6 h. Ethanol was evaporated under reduced pressure and the residue was washed with diethyl ether. The solid formed was dissolved in water (20 mL), acidified with saturated citric acid solution and filtered. The solid was further washed with water and dried under vacuum to afford 250 mg (57%) of 4,6-dicyano-1H-indole-2-carboxylic acid (I-2b) as a light brown solid.

Workup

  1. temperatureheated
  2. temperatureto reflux for 6 h
  3. customEthanol was evaporated under reduced pressure
  4. washthe residue was washed with diethyl ether
  5. customThe solid formed
  6. filtrationfiltered
  7. washThe solid was further washed with water
  8. customdried under vacuum

Sources & evidence

ORD record
ord-624abc5ad2cb42d39562f6d41aed5881
Source dataset
uspto-grants-2016_09
Patent number
US09447039B2

Reaction notes

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