Trifluoroacetic acid → 4-Bromo-2-(trifluoromethyl)-1,3-benzoxazole

HRID 1596602Notes

Reaction equation

HRID 1596602 reaction equation
[NH2:1][C:2]1[C:7]([Br:8])=[CH:6][CH:5]=[CH:4][C:3]=1[OH:9].[F:10][C:11]([F:16])([F:15])[C:12](O)=O>C(Cl)Cl>[Br:8][C:7]1[C:2]2[N:1]=[C:12]([C:11]([F:16])([F:15])[F:10])[O:9][C:3]=2[CH:4]=[CH:5][CH:6]=1

Participants

4

Reactant 2

HCID 6422Trifluoroacetic acidHCID 217022522-Amino-3-bromophenol

Product 1

HCID 217022614-Bromo-2-(trifluoromethyl)-1,3-benzoxazoleYield 16%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Conditions

Temperature
120 °C

Procedure

A solution of 2-amino-3-bromophenol (480 mg, 2.6 mmol), polyphosphoric ester (PPE, 3.4 g) and trifluoroacetic acid (0.88 mL, 11.5 mmol) was heated to 100° C. under a nitrogen atmosphere overnight. A reflux condenser was added as was fresh PPE and the reaction heated to 120° C. for 8 hr. The reaction was cooled and diluted with methylene chloride. The solvent was removed by rotoevaporation. The residue was dissolved in fresh methylene chloride and successively washed with 2N sodium hydroxide solution and saturated salt solution. After drying over anhydrous magnesium sulfate and filtering, the solvent was removed by rotoevaporation. The residue was purified by flash column chromatography in silica gel eluted with 15% acetone in hexanes to yield the title compound (110 mg, 16% yield).

Workup

  1. additionA reflux condenser was added
  2. temperatureThe reaction was cooled
  3. customThe solvent was removed by rotoevaporation
  4. dissolutionThe residue was dissolved in fresh methylene chloride
  5. washsuccessively washed with 2N sodium hydroxide solution and saturated salt solution
  6. dry with materialAfter drying over anhydrous magnesium sulfate
  7. filtrationfiltering
  8. customthe solvent was removed by rotoevaporation
  9. customThe residue was purified by flash column chromatography in silica gel
  10. washeluted with 15% acetone in hexanes

Sources & evidence

ORD record
ord-115c3b37d0c24af8aee3bc42aae2ffb0
Source dataset
uspto-grants-2001_09
Patent number
US06291511B1

Reaction notes

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