C([N-]C(C)C)(C)C.[Li+].[CH3:9][O:10][C:11](=[O:21])[CH2:12][C:13]1[CH:18]=[CH:17][CH:16]=[C:15]([O:19][CH3:20])[CH:14]=1.I[CH2:23][CH:24]1[CH2:28][CH2:27][CH2:26][CH2:25]1>O1CCCC1.CN1CCCN(C)C1=O.CN1CCCN(C)C1=O>[CH3:9][O:10][C:11](=[O:21])[CH:12]([C:13]1[CH:18]=[CH:17][CH:16]=[C:15]([O:19][CH3:20])[CH:14]=1)[CH2:23][CH:24]1[CH2:28][CH2:27][CH2:26][CH2:25]1
A solution of freshly prepared lithium diisopropylamide (23 mL of a 0.3 1M stock solution, 7.13 mmol) cooled to −78° C. was treated with (3-methoxy-phenyl)-acetic acid methyl ester (1.07 g, 5.94 mmol) in tetrahydrofuran/1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (14.8 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 (1.37 g, 6.53 mmol) in 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (1.16 mL). The reaction mixture was stirred at −78° C. for 3 h. The reaction was then warmed to 25° C. and was stirred at 25° C. for 16 h. At this time, the reaction was quenched by the dropwise addition of a saturated aqueous ammonium chloride solution. This solution was diluted with water (100 mL) and extracted into ethyl acetate (3×50 mL). The combined organic layers were washed with a saturated aqueous lithium chloride solution (1×75 mL), dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 95/5 hexanes/ethyl acetate) afforded 3-cyclopentyl-2-(3-methoxy-phenyl)-propionic acid methyl ester (1.39 g, 89.1%) as a clear oil: EI-HRMS m/e calcd for C16H22O3 (M+) 262.1568, found 262.1561.
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