Methyl 2-(3-nitrophenyl)acetate → 3-Cyclopentyl-2-(3-nitro-phenyl)-propionic acid methyl ester

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A solution of freshly prepared lithium diisopropylamide (43.3 mL of a 0.3M stock solution, 12.99 mmol) cooled to −78° C. was treated with (3-nitro-phenyl)-acetic acid methyl ester (2.45 g, 12.56 mmol) in tetrahydrofuran/1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (32 mL, 3:1). The resulting solution was stirred at −78° C. for 45 min. At this time, the reaction was treated with a solution of iodomethylcyclopentane (2.78 g, 13.23 mmol) in 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (2.78 mL), and the mixture was stirred at −78° C. for 3 h. The reaction was warmed to 25° C. and was stirred at 25° C. for 16 h. The reaction mixture was then quenched by the dropwise addition of a saturated aqueous ammonium chloride solution (25 mL) and was concentrated in vacuo. The residue was diluted with water (50 mL) and extracted with ethyl acetate (3×50 mL). The combined organic layers were washed with a saturated aqueous lithium chloride solution (2×25 mL), dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh 80/20 hexanes/ethyl acetate) afforded 3-cyclopentyl-2-(3-nitro-phenyl)-propionic acid methyl ester (1.63 g, 46.8%) as pale yellow oil: EI-HRMS m/e calcd for C15H19NO4 (M+) 277.1314, found 277.1317.

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