Sulfuric Acid → Ethyl 5-Bromoindole-2-carboxylate

HRID 1532350Notes

Reaction equation

HRID 1532350 reaction equation
S(=O)(=O)(O)O.[C:6]([O:11][CH2:12][CH3:13])(=[O:10])[C:7]([CH3:9])=O.Cl.[Br:15][C:16]1[CH:21]=[CH:20][C:19]([NH:22]N)=[CH:18][CH:17]=1>C(O)C>[Br:15][C:16]1[CH:17]=[C:18]2[C:19](=[CH:20][CH:21]=1)[NH:22][C:7]([C:6]([O:11][CH2:12][CH3:13])=[O:10])=[CH:9]2

Participants

5

Reactant 3

HCID 1118Sulfuric AcidHCID 12041Ethyl pyruvateHCID 121574-Bromophenylhydrazine hydrochloride

Product 1

HCID 259091Ethyl 5-Bromoindole-2-carboxylate

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

In a 500 ml flask, 14 g of 4-bromophenylhydrazine hydrochloride was dissolved in 170 ml of ethanol, and 1.2 ml of sulfuric acid and 8.5 ml of ethyl pyruvate were added. The reaction mixture was stirred for about 2 hours at room temperature and evaporated under reduced pressure to dryness. To the residue was added 23 ml of polyphosphoric acid, and the resulting solution was then stirred for 2 hours at 100° C.-110° C. After water was added, the reaction solution was neutralized with saturated aqueous NaHCO3 solution and then extracted to times with ethyl acetate. The extracts were combined, dried over MgSO4 and then evaporated. The residue was purified with silica gel column chromatography [eluent: n-hexane/ethyl acetate(9:1)] to obtain 10 g of the title compound as a brown solid.

Workup

  1. customevaporated under reduced pressure to dryness
  2. additionTo the residue was added 23 ml of polyphosphoric acid
  3. stirringthe resulting solution was then stirred for 2 hours at 100° C.-110° C
  4. additionAfter water was added
  5. extractionextracted to times with ethyl acetate
  6. dry with materialdried over MgSO4
  7. customevaporated
  8. customThe residue was purified with silica gel column chromatography [eluent: n-hexane/ethyl acetate(9:1)]

Sources & evidence

ORD record
ord-26312d731616405c9c0b803b7ed6a086
Source dataset
uspto-grants-2001_03
Patent number
US06201006B1

Reaction notes

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