[N+:1]([C:4]1[CH:9]=[CH:8][C:7]([CH2:10][C:11](=[S:13])[NH2:12])=[CH:6][CH:5]=1)([O-:3])=[O:2].Br[CH2:15][C:16](=O)[CH2:17][CH3:18]>C(O)C>[CH2:17]([C:16]1[N:12]=[C:11]([CH2:10][C:7]2[CH:6]=[CH:5][C:4]([N+:1]([O-:3])=[O:2])=[CH:9][CH:8]=2)[S:13][CH:15]=1)[CH3:18]A mixture of 2-(4-nitrophenyl)ethanethioamide (1.50 g), 1-bromo-2-butanone (1.27 g) and ethanol (50 mL) was heated under reflux for 30 min. The reaction mixture was concentrated, and ethyl acetate was added to the residue. The mixture was washed successively with saturated aqueous sodium hydrogen carbonate and saturated brine, dried over anhydrous magnesium sulfate and concentrated. The residue was subjected to silica gel column chromatography, and 4-ethyl-2-(4-nitrobenzyl)-1,3-thiazole was obtained as a brown oil (1.59 g, yield 84%) from a fraction eluted with hexane-ethyl acetate (7:1-4:1, v/v).
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