Phenylhydrazine → 1H-Indole, 2-(2-benzofuranyl)-

HRID 476411Notes

Reaction equation

HRID 476411 reaction equation
[C:1]1([NH:7]N)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[C:9]([C:12]1[O:13][C:14]2[CH:20]=[CH:19][CH:18]=[CH:17][C:15]=2[CH:16]=1)(=O)[CH3:10]>C(O)C.C(O)(=O)C>[CH:4]1[CH:5]=[C:6]2[CH:10]=[C:9]([C:12]3[O:13][C:14]4[C:15](=[CH:17][CH:18]=[CH:19][CH:20]=4)[CH:16]=3)[NH:7][C:1]2=[CH:2][CH:3]=1

Participants

5

Reactant 2

HCID 7516PhenylhydrazineHCID 154352-Acetylbenzofuran

Product 1

HCID 99915851H-Indole, 2-(2-benzofuranyl)-Yield 48%

Reagents, catalysts & solvents 2

HCID 176Acetic AcidCatalystHCID 702EthanolSolvent

Conditions

Temperature
80 °C

Procedure

Phenylhydrazine (97%; 6.3 ml, 1 eq) is introduced into a solution of 2-acetylbenzofuran (10 g, 1 eq) in ethanol (25 ml). After adding 20 drops of glacial acetic acid, the mixture is stirred at 80° C. for 1 h. Subsequently, the solvent is distilled off. The residue is introduced gradually into polyphosphoric acid (100 g), heated to 120° C. and stirred for 1 h. The reaction output is added cautiously to ice-water and neutralized with 2M NaOH. The precipitate is filtered off and washed with distilled water. The residue is dried under reduced pressure. After recrystallization in ethyl acetate/n-hexane, 7.0 g are obtained. Yield: 48%

Workup

  1. distillationSubsequently, the solvent is distilled off
  2. additionThe residue is introduced gradually into polyphosphoric acid (100 g)
  3. temperatureheated to 120° C.
  4. stirringstirred for 1 h
  5. additionThe reaction output is added cautiously to ice-water and neutralized with 2M NaOH
  6. filtrationThe precipitate is filtered off
  7. washwashed with distilled water
  8. customThe residue is dried under reduced pressure
  9. customAfter recrystallization in ethyl acetate/n-hexane
  10. custom7.0 g are obtained

Sources & evidence

ORD record
ord-8dce75f8c0114df9b6d9f7548f2e860b
Source dataset
uspto-grants-2014_01
Patent number
US08637857B2

Reaction notes

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