C(NC(C)C)(C)C.C([Li])CCC.[CH3:13][O:14][CH2:15][S:16][C:17]1[CH:22]=[CH:21][C:20]([CH2:23][C:24]([OH:26])=[O:25])=[CH:19][CH:18]=1.I[CH2:28][CH:29]1[CH2:33][CH2:32][CH2:31][CH2:30]1>O1CCCC1.CN1CCCN(C)C1=O>[CH:29]1([CH2:28][CH:23]([C:20]2[CH:21]=[CH:22][C:17]([S:16][CH2:15][O:14][CH3:13])=[CH:18][CH:19]=2)[C:24]([OH:26])=[O:25])[CH2:33][CH2:32][CH2:31][CH2:30]1
A solution of diisopropylamine (0.37 mL, 2.62 mmol) in tetrahydrofuran (2 mL) was cooled to −78° C. and then treated with a 2.5M solution of n-butyllithium in hexanes (1.05 mL, 2.62 mmol). This solution was stirred at −78° C. for 30 min and then treated with a solution of (4-methoxymethylsulfanyl-phenyl)-acetic acid (223 mg, 1.05 mmol) in tetrahydrofuran (1.5 mL) and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (0.5 mL). The reaction mixture was allowed to stir at −78° C. for 1 h. At this time, the reaction was treated with iodomethylcyclopentane (328 mg, 1.56 mmol). The reaction mixture was allowed to slowly warm to 25° C. where it was stirred for 18 h. At this time, the reaction, mixture was quenched with a saturated aqueous sodium bicarbonate solution and then concentrated in vacuo. The residue was treated with a 1N aqueous sodium hydroxide solution and extracted with ethyl acetate. The aqueous layer was then acidified with concentrated hydrochloric acid. This solution was extracted with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated in vacuo. Biotage chromatography (FLASH 12M, Silica, 80/20 hexanes/ethyl acetate) afforded 3-cyclopentyl-2-(4-methoxymethylsulfanyl-phenyl)-propionic acid (202 mg, 65%) as an off-white solid: mp 167–170° C.; EI-HRMS m/e calcd for C16H22O3S (M+) 294.1290, found 294.1288.
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