Acetone → Ethyl 2-[2-(4-bromophenyl)-2-oxoethyl]pentanoate

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To a 200 mL flask was added crude 2-[2-(4-bromophenyl)-2-oxoethyl]-2-propylmalonate (7.62 g, 19.2 mmol), acetone (21 mL), and ethanol (19 mL), followed by addition of 1 N aqueous sodium hydroxide solution (19.1 mL). The reaction mixture was heated to 55° C. for 3 h. The clear, orange-red reaction mixture was then concentrated under reduced pressure and the residue was redissolved in dimethoxyethane (30 mL). The mixture was heated to 80° C. for 3 h. The reaction mixture was cooled to rt, diluted with ethyl acetate (100 mL) and water (100 mL), and stirred for 15 minutes until almost all color was extracted into the organic layer. The layers were separated and the aqueous layer extracted with additional ethyl acetate (75 mL). The combined organic layers were washed with saturated aqueous sodium chloride solution (75 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure to afford an orange oil. The crude product was purified by flash chromatography (10:1 hexane:ethyl acetate) to afford ethyl 2-[2-(4-bromophenyl)-2-oxoethyl]pentanoate (1.33 g, 20%). LC-MS ret. time 3.60 min, m/z 326.05 (MH+); 1H NMR (300 MHz, CDCl3) δ 0.87 (t, 3H), 1.25 (t, 3H), 1.29-1.43 (m, 2H), 1.57-1.73 (m, 2H), 2.90-3.08 (m, 2H), 3.34-3.47 (m, 2H), 4.15 (q, 21), 7.59 (d, 4), 7.82 (d, 2H).

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