Diisopropylamine → 2-(3-Chloro-4-methylsulfanyl-phenyl)-3-cyclopentyl-propionic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of diisopropylamine (4.86 mL, 34.70 mmol) in dry tetrahydrofuran (212.3 mL) was cooled to −78° C. and then treated with a 2.5M solution of n-butyllithium in hexanes (13.88 mL, 34.70 mmol). The resulting reaction mixture was stirred at −78° C. for 15 min and then slowly treated with a solution of (3-chloro-4-methylsulfanyl-phenyl)-acetic acid methyl ester (7.28 g, 31.55 mmol) in dry tetrahydrofuran (23.6 mL) and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (9.43 mL). The resulting bright yellow solution was allowed to stir at −78° C. for 1 h, at which time, a solution of iodomethylcyclopentane (prepared as in Example 1, 7.95 g, 37.86 mmol) in 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (7.08 mL) was slowly added. The reaction mixture was allowed to warm to 25° C. where it was stirred overnight. The reaction mixture was then quenched with a saturated aqueous ammonium chloride solution (20 mL), and the layers were separated. The aqueous layer was extracted with ethyl acetate (3×20 mL). The combined organic layers were dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230–400 mesh, 19/1 hexanes/ethyl acetate) afforded 2-(3-chloro-4-methylsulfanyl-phenyl)-3-cyclopentyl-propionic acid methyl ester (5.74 g, 58.1%) as a colorless oil.

Provenance & Evidence