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Dimethyl oxalate (15.27 g, 0,129 mol), and 4'-chloroacetophenone (20.0 g, 0.129 mol) were added to methanol (300 mL). Sodium methoxide (25 wt. % in methanol, 70 mL) was added dropwise over about 0.5 hour. The reaction was stirred at room temperature for 16 hours, whereupon the sodium salt of the butanoate precipitated from solution. The mixture was treated with 70 mL of conc. HCl 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). After drying in vacuo, methyl 4-[4-(chloro)phenyl]-3-ketobutyrate was obtained (16.94 g, 54.4%) as the enol: 1H NMR (CDCl3 /300 MHz) 8 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).

1. customprecipitated from solution
2. additionThe mixture was treated with 70 mL of conc. HCl
3. temperatureThe suspension was cooled to 0° C.
4. waitheld for 0.5 hour
5. filtrationThe solid was filtered
6. washthe filter cake was washed with cold water (100 mL)
7. customAfter drying in vacuo