3-(Trifluoromethyl)benzeneacetic acid → 3-Cyclopentyl-2-(3-trifluoromethyl-phenyl)-propionic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of freshly prepared lithium diisopropylamide (35.32 mL of a 0.31M stock solution, 10.9 mmol) cooled to −78° C. was treated with (3-trifluoromethyl-phenyl)-acetic acid (1.02 g, 5.0 mmol) in tetrahydrofuran/1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (12.4 mL, 3:1). The resulting solution was stirred at −78° C. for 3 h. Iodomethylcyclopentane (1.16 g, 5.52 mmol) was then added in 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (1.16 mL). The reaction mixture was stirred at −78° C. for 4 h. The reaction was then warmed to 25° C. and was stirred at 25° C. for 48 h. This solution was then quenched by the slow addition of the reaction mixture to a 2N aqueous hydrochloric acid solution (50 mL). The product was extracted into ethyl acetate (3×100 mL) and diethyl ether (1×50 mL). The combined organic layers were washed with a saturated aqueous lithium chloride solution (2×100 mL) and a saturated aqueous sodium chloride solution (1×150 mL), dried over magnesium sulfate and sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 50/50 hexanes/ethyl acetate with acetic acid) afforded 3-cyclopentyl-2-(3-trifluoromethyl-phenyl)-propionic acid (1.16 g, 80.5%) as an off-white solid: mp 64-65° C.; EI-HRMS m/e calcd for C15H17F3O2 (M+Na+) 309.1079, found 309.1084.

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