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

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Reaction Steps

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.

Provenance & Evidence