Ethyl bromopyruvate → Ethyl 2-(4-fluorophenyl)-1,3-oxazole-4-carboxylate

A mixture of p-fluorobenzamide (5 g), ethyl bromopyruvate (9.92 ml), and sodium hydrogen carbonate (15 g) in tetrahydrofuran (150 ml) was refluxed for 20 hours. After cooling the reaction mixture, insoluble material was removed by filtration through Cellite and the filtrate was concentrated under reduced pressure. The residue was dissolved in tetrahydrofuran (30 ml) and trifluoroacetic anhydride (30 ml) was added to the mixture in an ice bath. After stirring at room temperature for one hour, a saturated aqueous sodium hydrogen carbonate solution was added to the mixture in an ice bath, and the mixture was extracted with ethyl acetate. The organic layer was washed with brine, dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (solvent: ethyl acetate n-hexane=1:9) to obtain ethyl 2-(4-fluorophenyl)oxazol-4-carboxylate (7.44 g) as colorless solid.

1. temperaturewas refluxed for 20 hours
2. temperatureAfter cooling the reaction mixture, insoluble material
3. customwas removed by filtration through Cellite
4. concentrationthe filtrate was concentrated under reduced pressure
5. dissolutionThe residue was dissolved in tetrahydrofuran (30 ml)
6. additiontrifluoroacetic anhydride (30 ml) was added to the mixture in an ice bath
7. additiona saturated aqueous sodium hydrogen carbonate solution was added to the mixture in an ice bath
8. extractionthe mixture was extracted with ethyl acetate
9. washThe organic layer was washed with brine
10. dry with materialdried over anhydrous sodium sulfate
11. customthe solvent was removed under reduced pressure
12. customThe resulting residue was purified by silica gel column chromatography (solvent: ethyl acetate n-hexane=1:9)

ORD record

ord-44bef0ae0e3a4585bc85e3ac9a9ec3c5

Source dataset

uspto-grants-2010_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07759373B2