Ethyl 5-methoxyindole-2-carboxylate → Ethyl 5-hydroxy-1H-indole-2-carboxylate

HRID 1166055Notes

Reaction equation

HRID 1166055 reaction equation
B(Br)(Br)Br.C[O:6][C:7]1[CH:8]=[C:9]2[C:13](=[CH:14][CH:15]=1)[NH:12][C:11]([C:16]([O:18][CH2:19][CH3:20])=[O:17])=[CH:10]2>ClCCl>[OH:6][C:7]1[CH:8]=[C:9]2[C:13](=[CH:14][CH:15]=1)[NH:12][C:11]([C:16]([O:18][CH2:19][CH3:20])=[O:17])=[CH:10]2

Participants

4

Reactant 2

HCID 20926Ethyl 5-methoxyindole-2-carboxylateHCID 25134Boron tribromide

Product 1

HCID 90677Ethyl 5-hydroxy-1H-indole-2-carboxylateYield 48.2%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

Boron tribromide (64.58 g) was added dropwise to a stirred solution of ethyl 5-methoxyindole-2-carboxylate (20 g) in dry dichloromethane (1000 ml) at −78° C. under an atmosphere of argon. The reaction was allowed to warm to room temperature and stirred for a further 2 hours. The reaction was poured into ice/saturated aqueous sodium hydrogen carbonate solution with stirring and extracted with ethyl acetate. Combined organic extracts were washed with saturated aqueous sodium hydrogen carbonate solution, water, aqueous saturated sodium chloride solution and dried (MgSO4). The solution was concentrated in vacuo and the residue was purified by column chromatography using 0-60% diethyl ether iso-hexane as eluent to give product as a white solid (9.02 g, 48%); NMR δ(CD3SOCD3) 1.31 (t, 3H), 4.29 (q, 2H), 6.79 (dd, 1H), 6.90 (dd, 1H), 7.22 (d, 1H), 8.84 (s, 1H), 11.52 (brs, 1H), M/z (+) 206 (MH+).

Workup

  1. additionThe reaction was poured into ice/saturated aqueous sodium hydrogen carbonate solution
  2. stirringwith stirring
  3. extractionextracted with ethyl acetate
  4. washCombined organic extracts were washed with saturated aqueous sodium hydrogen carbonate solution, water, aqueous saturated sodium chloride solution
  5. dry with materialdried (MgSO4)
  6. concentrationThe solution was concentrated in vacuo
  7. customthe residue was purified by column chromatography

Sources & evidence

ORD record
ord-b927751d9faf46ed9523f7ab2659f177
Source dataset
uspto-grants-2003_09
Patent number
US06613760B1

Reaction notes

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