反应详情

To a solution of 3-(4-methyl-3-nitrophenyl)-1,2,4-oxadiazol-5(4H)-one (106) (12 g, 54.26 mmol) in POCl3 (120 mL) was added N,N-dimethylformamide (12 mL). The resulted solution was heated to reflux for 72 hours then concentrated under vacuum. The residue was dissolved in water (250 mL) and extracted with ethyl acetate (3×250 mL). The combined organic layers were washed with brine (3×250 mL), dried over anhydrous sodium sulfate and concentrated under vacuum. The residue was purified by flash chromatography (PE/EA=10:1) to afford 5-chloro-3-(4-methyl-3-nitrophenyl)-1,2,4-oxadiazole (107) as a white solid. 1H NMR (300 MHz, CDCl3) δ 8.64 (dd, J=1.5, 8.4 Hz, 1H), 8.18 (dd, J=1.5, 7.8 Hz, 1H), 7.56 (d, J=8.1 Hz, 1H), 2.70 (s, 3H). MS m/z 240.7 (M+1)+.

1. temperatureThe resulted solution was heated
2. temperatureto reflux for 72 hours
3. concentrationthen concentrated under vacuum
4. dissolutionThe residue was dissolved in water (250 mL)
5. extractionextracted with ethyl acetate (3×250 mL)
6. washThe combined organic layers were washed with brine (3×250 mL)
7. dry with materialdried over anhydrous sodium sulfate
8. concentrationconcentrated under vacuum
9. customThe residue was purified by flash chromatography (PE/EA=10:1)