Hydrochloric Acid → Methyl 1-[2-(4-bromophenyl)-2-oxoethyl]cyclopentanecarboxylate

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To a 150 mL flask was added dichloromethane (70 mL), methyl 1-(2-chloro-2-oxoethyl)cyclopentanecarboxylate] (3.50 g, 16.8 mmol) [prepared as described by Bajaj, et al., J. Indian Chem. Soc. 52:1076-78, 1975] and bromobenzene (2.77 g, 17.6 mmol), and the reaction mixture cooled to 0° C. before aluminum trichloride (4.77 g, 35.7 mmol) was slowly added. The mixture was stirred for 1 h at 0° C., then for 12 h at rt. The reaction mixture was slowly poured into 50 mL chilled (0° C.) 1 N aqueous hydrochloric acid solution. Water (50 mL) was added, followed by ethyl acetate (100 mL), and the mixture stirred for 30 minutes. The layers were separated and the aqueous layer extracted with additional ethyl acetate (100 mL). The combined organic layer was washed with saturated aqueous sodium chloride (100 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure to yield a brown oil which was purified by flash chromatography (10:1/hexane:ethyl acetate) to afford methyl 1-[2-(4-bromophenyl)-2-oxoethyl]cyclopentane carboxylate as a yellow, crystalline solid (1.62 g, 30%). LC-MS ret. time 3.45 min, m/z 324.8 (MH+); 1H NMR (300 MHz, CDCl3) δ 1.50-1.83 (overlapping signals, 6H), 2.22-2.33 (m, 2H), 3.37 (s, 2H), 3.66 (s, 3H), 7.59 (d, 2H), 7.80 (d, 2H).

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