Ethyl Acetate → 6-Bromo-2-tert-butyl-7-nitro-1,3-benzoxazole-4-carboxylic Acid

HRID 17515Notes

Reaction equation

HRID 17515 reaction equation
[Br:1][C:2]1[C:3]([N+:19]([O-:21])=[O:20])=[C:4]([OH:18])[C:5]([NH:11][C:12](=O)[C:13]([CH3:16])([CH3:15])[CH3:14])=[C:6]([CH:10]=1)[C:7]([OH:9])=[O:8].O.C1(C)C=CC(S(O)(=O)=O)=CC=1.C(OCC)(=O)C>C1C=CC=CC=1.[Cl-].[Na+].O>[Br:1][C:2]1[C:3]([N+:19]([O-:21])=[O:20])=[C:4]2[O:18][C:12]([C:13]([CH3:16])([CH3:15])[CH3:14])=[N:11][C:5]2=[C:6]([C:7]([OH:9])=[O:8])[CH:10]=1

Participants

6

Reactant 3

HCID 8857Ethyl AcetateHCID 521998p-Toluenesulfonic acid monohydrateHCID 86630865HCID 86630865, compound

Product 1

HCID 685852286-Bromo-2-tert-butyl-7-nitro-1,3-benzoxazole-4-carboxylic AcidYield 99.7%

Reagents, catalysts & solvents 2

HCID 241BenzeneSolventHCID 57417360Sodium chloride; waterSolvent

Procedure

5-Bromo-2-(2,2-dimethylpropionylamino)-3-hydroxy-4-nitrobenzoic acid (I-221) (1.90 g, 5.26 mmol) was dissolved in benzene (38 ml), then p-toluenesulfonic acid monohydrate (1.00 g, 5.26 mmol) was added at room temperature. Under nitrogen atmosphere, the reaction liquid was heated under reflux for 21 hours, then cooled to room temperature. The reaction liquid was fractionated with ethyl acetate and saturated brine. The organic layer was washed with saturated brine, and dried over anhydrous sodium sulfate. The insoluble matter was removed by filtration, the solvent was evaporated away and the resulting residue was purified by middle-pressure liquid chromatography (eluent, ethyl acetate:methanol=4:1) to obtain the entitled compound (1.80 g, 98%) as a brown solid.

Workup

  1. customUnder nitrogen atmosphere, the reaction liquid
  2. temperaturewas heated
  3. temperatureunder reflux for 21 hours
  4. customThe reaction liquid
  5. washThe organic layer was washed with saturated brine
  6. dry with materialdried over anhydrous sodium sulfate
  7. customThe insoluble matter was removed by filtration
  8. customthe solvent was evaporated away
  9. customthe resulting residue was purified by middle-pressure liquid chromatography (eluent, ethyl acetate:methanol=4:1)

Sources & evidence

ORD record
ord-f50dc37f50f14875b7a895039780ca78
Source dataset
uspto-grants-2010_06
Patent number
US07737166B2

Reaction notes

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