[N+:1]([C:4]1[CH:11]=[CH:10][C:7]([CH:8]=O)=[CH:6][CH:5]=1)([O-:3])=[O:2].[C:12]([NH:15][CH2:16][C:17]([OH:19])=[O:18])(=O)[CH3:13].C([O-])(=O)C.[Na+].C(OC(=O)C)(=O)C>>[CH3:13][C:12]1[O:19][C:17](=[O:18])[C:16](=[CH:8][C:7]2[CH:10]=[CH:11][C:4]([N+:1]([O-:3])=[O:2])=[CH:5][CH:6]=2)[N:15]=14-Nitrobenzaldehyde (53.7 g, 0.356 mol), N-acetylglycine (49.9 g, 0.427 mol) and sodium acetate (37.9 g, 0.463 mol) were mixed with acetic anhydride (168 g, 1.78 mol) and the resulting mixture heated with stirring to 120° C. for 6 hrs, giving a dark suspension. The mixture was then cooled to RT overnight, resulting in the formation of a precipitated solid. The reaction mixture was poured into ice-water (150 g) and the resulting suspended solid was collected by filtration. The crude solid product was washed with acetone (100 ml) then recrystallized from hot acetone (650 ml) to give a crystalline solid that was washed with 50% aqueous ethanol, then dried in vacuo to give 2-methyl-4-(4-nitrobenzylidene)oxazol-5(4H)-one (55.0 g, 66%) as pale yellow needles. The crystallisation mother liquors and washes were combined and evaporated to give a solid residue that was recrystallized from acetone to give a second crop of 2-methyl-4-(4-nitrobenzylidene)oxazol-5(4H)-one (8 g, 10%). The combined yield of 2-methyl-4-(4-nitrobenzylidene)oxazol-5(4H)-one was 63 g (76%)
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