[CH3:1][O:2][C:3]1[CH:4]=[C:5]([CH2:11][C:12](Cl)=[O:13])[CH:6]=[CH:7][C:8]=1[O:9][CH3:10].[NH2:15][C:16](=[N:22]O)[C:17]([O:19][CH2:20][CH3:21])=[O:18].C(N(CC)C(C)C)(C)C.O>ClCCl>[CH3:1][O:2][C:3]1[CH:4]=[C:5]([CH:6]=[CH:7][C:8]=1[O:9][CH3:10])[CH2:11][C:12]1[O:13][N:22]=[C:16]([C:17]([O:19][CH2:20][CH3:21])=[O:18])[N:15]=12-(3,4-dimethoxyphenyl)acetyl chloride (0.650 mL; 3.78 mmol) was added to a mixture of ethyl 2-amino-2-(hydroxyimino)acetate (0.500 g; 3.78 mmol) and N,N diisopropylethylamine (1.05 mL; 6.06 mmol) in dichloromethane (18 mL) at −15° C. The reaction mixture was stirred at room temperature overnight and poured into a mixture of ice and water. The formed precipitate was filtered off, suspended in pyridine (18 mL) and refluxed in a sealed tube for 20 h and concentrated under reduced pressure. The crude material was purified by flash chromatography on silica (eluent 20 to 100% ethyl acetate in heptane) to yield 0.395 g (36%) of ethyl 5-(3,4-dimethoxybenzyl)-1,2,4-oxadiazole-3-carboxylate as a yellow solid.
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