反应详情

A solution of ethyl 2-formyloxazole-4-carboxylate (650 mg, 3.84 mmol) in methanol (25 mL) was cooled to 0° C. and 50% aqueous hydroxylamine (0.22 mL, 7.68 mmol) was added dropwise. The reaction mixture was stirred at room temperature for 3 h. Solvent was removed under reduced pressure and the crude product (0.52 g) obtained was dissolved in DMF (20 mL). T3P (3.4 mL, 5.65 mmol; 50% in EtOAc) was added to the reaction mixture and heated to 100° C. for 2 h. The reaction mixture was quenched with saturated NaHCO3 solution and the organic product was extracted with EtOAc. Solvent was removed under reduced pressure and the crude product was purified by column chromatography (silica gel 60-120 mesh, eluent 10% EtOAc in petroleum ether) to afford ethyl 2-cyanooxazole-4-carboxylate (0.34 g, yield 53%) as an off white solid. 1H NMR (300 MHz, CDCl3) δ 8.39 (s, 1H), 4.48-4.41 (q, J=7.0 Hz, 2H), 1.44-1.39 (t, J=7.0 Hz, 3H).

1. customSolvent was removed under reduced pressure
2. customthe crude product (0.52 g) obtained
3. temperatureheated to 100° C. for 2 h
4. customThe reaction mixture was quenched with saturated NaHCO3 solution
5. extractionthe organic product was extracted with EtOAc
6. customSolvent was removed under reduced pressure
7. customthe crude product was purified by column chromatography (silica gel 60-120 mesh, eluent 10% EtOAc in petroleum ether)