2-Oxobutanoic Acid → Ethyl 3-methyl-1H-indole-2-carboxylate

HRID 642424Notes

Reaction equation

HRID 642424 reaction equation
[C:1]1([NH:7]N)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.O=[C:10]([CH2:14][CH3:15])[C:11]([OH:13])=[O:12].[CH3:16][CH2:17]O>>[CH2:16]([O:13][C:11]([C:10]1[NH:7][C:1]2[C:6]([C:14]=1[CH3:15])=[CH:5][CH:4]=[CH:3][CH:2]=2)=[O:12])[CH3:17]

Participants

4

Reactant 3

HCID 582-Oxobutanoic AcidHCID 702EthanolHCID 7516Phenylhydrazine

Product 1

HCID 593963Ethyl 3-methyl-1H-indole-2-carboxylate

Procedure

A mixture of phenyl hydrazine (8.92 g), 2-oxo-butyric acid (10.11 g), TsOH mono hydrate (47.1 g) in EtOH (200 mL) was refluxed overnight, then cooled, the solids were filtered off and briefly washed with EtOH, all liquids were combined and concentrated to give a residue, which was subsequently partitioned between EtOAc and water, the organic phase was washed with sat. NaHCO3 solution, and sat. NaCl solution respectively, then dried over anhydrous sodium sulfate, filtered, concentrated and crystallized to give product (15.6 g). 1H NMR (200 MHz, CDCl3): δ (ppm)=8.65 (br, s, 1H), 7.63 (d, 1H), 7.40-7.10 (m, 3H), 4.40 (q, 2H, J=7.1 Hz), 2.61 (s, 3H), 1.43 (t, 3H, J=7.1 Hz).

Workup

  1. temperaturewas refluxed overnight
  2. temperaturecooled
  3. filtrationthe solids were filtered off
  4. washbriefly washed with EtOH
  5. concentrationconcentrated
  6. customto give a residue, which
  7. customwas subsequently partitioned between EtOAc and water
  8. washthe organic phase was washed with sat. NaHCO3 solution, and sat. NaCl solution respectively
  9. dry with materialdried over anhydrous sodium sulfate
  10. filtrationfiltered
  11. concentrationconcentrated
  12. customcrystallized

Sources & evidence

ORD record
ord-6daaae2468bf48698021c28f66953854
Source dataset
uspto-grants-2010_04
Patent number
US07696223B2

Reaction notes

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