A solution of diisopropylamine (457 μL, 3.26 mmol) in tetrahydrofuran (5 mL) was cooled to −78° C. under a nitrogen atmosphere and then treated with a 2.5 M solution of n-butyllithium in hexanes (1.3 mL, 3.26 mmol). The mixture was stirred at −78° C. for 30 min, at which time, a solution of (3-chloro-4-methylsulfanyl-phenyl)-acetic acid ethyl ester (0.67 g, 2.75 mmol) in tetrahydrofuran (8 mL) was slowly added to the reaction mixture. The reaction mixture turned deep yellow in color. The reaction mixture was then further stirred at −78° C. for 30 min, at which time, a solution of iodomethylcyclopentane (0.65 g, 3.09 mmol) in 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidone (1 mL) was added via syringe. The reaction mixture was then allowed to warm to 25° C., where it was stirred for 16 h. The reaction mixture turned red in color during this time period. The reaction mixture was quenched with a 6 N aqueous hydrochloric acid solution (5 mL) and further diluted with water (20 mL). The reaction mixture was then extracted with methylene chloride (3×20 mL). The combined organic layers were washed with a saturated aqueous sodium chloride solution (1×25 mL), dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 4/1 hexanes/ethyl acetate) afforded 2-(3-chloro-4-methylsulfanyl-phenyl)-3-cyclopentyl-propionic acid ethyl ester (0.50 g, 56%) as a light yellow oil.
