Water → 4,6-Dibromo-5-hydroxy-1-benzofuran-2-carboxylic acid

HRID 642938Notes

Reaction equation

HRID 642938 reaction equation
C(C1OC2C=CC(O)=CC=2C=1)(O)=O.[Br:14][C:15]1[C:20]2[CH:21]=[C:22]([C:24]([OH:26])=[O:25])[O:23][C:19]=2[CH:18]=[C:17]([Br:27])[C:16]=1[OH:28].C([O-])(=O)C.[K+].BrBr.O>C(O)(=O)C>[Br:14][C:15]1[C:20]2[CH:21]=[C:22]([C:24]([OH:26])=[O:25])[O:23][C:19]=2[CH:18]=[C:17]([Br:27])[C:16]=1[OH:28]

Participants

6

Reactant 4

HCID 962WaterHCID 24408BromineHCID 517044Potassium AcetateHCID 131728055HCID 131728055, compound

Product 1

HCID 592602364,6-Dibromo-5-hydroxy-1-benzofuran-2-carboxylic acid

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent2×

Conditions

Temperature
0 °C

Procedure

Preparation of 2-carboxy-5-hydroxybenzofuran 2-Carboxy-5-methoxybenzofuran (1.0 g, 5.2 mmol) was dissolved in anhydrous dichloromethane (25 ml) and cooled to −78° C. A 1 M solution of borontribromide (15.6 ml) in dichloromethane was added slowly. The reaction mixture was allowed to warm to ambient temperature under an atmosphere of nitrogen, and stirred 4 hours. The solution was quenched with aqueous ammonium chloride (20 ml) and extracted with ethyl acetate. The aqueous layer was washed with water and dried over sodium sulfate. 0.9 g (100%) of crude product was obtained. 1H NMR(CD3OD) δ=6.84 (dd, 1H), 6.95 (d, 1H), 7.17 (s, 1H), 7.32 (d, 1H). Step 2: Preparation of 4,6-dibromo-2-carboxy-5-hydroxybenzofuran 2-carboxy-5-hydroxybenzofuran (980 mg, 5.50 mmol) and potassium acetate (1.10 g, 11.21 mmol) were dissolved in acetic acid (30 ml) and cooled to 0° C. Bromine (845 μl, 16.50 mmol) was dissolved in acetic acid (2 ml) and added slowly to the above solution. The reaction mixture was allowed to warm to ambient temperature under an atmosphere of nitrogen, and stirred 2.5 hours. Water (20 ml) was then added to the solution and the reaction quenched upon the addition of Na2S2O3-5H2O (260 mg). The aqueous solution was extracted with diethyl ether, and the organic layer washed with aqueous sodium thiosulfate and dried over sodium sulfate. Concentration in vacuo yielded a tan solid which was washed with hexanes to yield 1.04 g (56%). 1H NMR (CD3OD) δ=7.39 (s, 1H), 7.82 (s, 1H).

Workup

  1. additionadded slowly to the above solution
  2. temperatureto warm to ambient temperature under an atmosphere of nitrogen
  3. customthe reaction quenched upon the addition of Na2S2O3-5H2O (260 mg)
  4. extractionThe aqueous solution was extracted with diethyl ether
  5. washthe organic layer washed with aqueous sodium thiosulfate
  6. dry with materialdried over sodium sulfate
  7. concentrationConcentration in vacuo
  8. customyielded a tan solid which
  9. washwas washed with hexanes
  10. customto yield 1.04 g (56%)

Sources & evidence

ORD record
ord-1d27b4ebebfd495094e684d2eea96fdf
Source dataset
uspto-grants-2010_04
Patent number
US07696365B2

Reaction notes

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