[C:1]([O:7][CH3:8])(=[O:6])[C:2]([O:4]C)=O.[Cl:9][C:10]1[CH:15]=[CH:14][C:13]([C:16](=[O:18])[CH3:17])=[CH:12][CH:11]=1.Cl>CO.C[O-].[Na+]>[CH3:8][O:7][C:1](=[O:6])[C:2](=[O:4])[CH2:17][C:16]([C:13]1[CH:14]=[CH:15][C:10]([Cl:9])=[CH:11][CH:12]=1)=[O:18]Dimethyl oxalate (15.27 g, 0.129 mol) and 4′-chloroacetophenone (20.0 g, 0.129 mol) were diluted with methanol (300 mL) and sodium methoxide (25 wt % in methanol, 70 mL) was added in one portion. The reaction was stirred at room temperature for 16 hours (the reaction became an insoluble mass during this time). The solid was mechanically broken up, hydrochloric acid (conc. 70 mL) was added, and the white suspension was stirred vigorously at room temperature for 1 hour. The suspension was cooled to 0° C. and held for 0.5 hour. The solid was filtered, and the filter cake was washed with cold water (100 mL). Upon drying, methyl-4-[4-(chloro)phenyl]-2,4-dioxobutanoate was obtained (16.94 g, 54.4%) as the enol: mp 108.5–110.5° C. 1H NMR (CDCl3/300 MHz) δ 7.94 (d, J=8.66 Hz, 2H), 7.48 (d, J=8.66 Hz, 2H), 7.04 (s, 1H), 3.95 (s, 3H), 3.48 (s, 1H).
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