[N+:1]([C:4]1[CH:9]=[CH:8][C:7]([CH2:10][C:11]([NH2:13])=[O:12])=[CH:6][CH:5]=1)([O-:3])=[O:2].Br[CH2:15][C:16](=O)[CH3:17].CN(C)C=O.C(=O)([O-])[O-].[K+].[K+]>C(OCC)(=O)C.O>[CH3:17][C:16]1[N:13]=[C:11]([CH2:10][C:7]2[CH:6]=[CH:5][C:4]([N+:1]([O-:3])=[O:2])=[CH:9][CH:8]=2)[O:12][CH:15]=1A mixture of 2-(4-nitrophenyl)acetamide (15.0 g), 1-bromo-2-propanone (19.03 g), and N,N-dimethylformamide (2 mL) was stirred at 120° C. for 3 hrs. Water, potassium carbonate and ethyl acetate were added to basify the reaction mixture and the mixture was extracted with ethyl acetate. Insoluble materials were filtered off, and the organic layer was separated. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate and concentrated. The residue was subjected to silica gel column chromatography to give 4-methyl-2-(4-nitrobenzyl)-1,3-oxazole as orange crystals (1.50 g, yield 8.2%) from a fraction eluted with hexane-ethyl acetate (2:1, v/v). Recrystallization thereof from ethyl acetate-hexane gave colorless prism crystals. melting point: 67-68° C.
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