Dimethylformamide → 5-Chloro-3-(4-methyl-3-nitrophenyl)-1,2,4-oxadiazole

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Reaction Steps

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)+.

Provenance & Evidence