C[O:2][C:3](=[O:20])[CH:4]([C:11]1[CH:16]=[CH:15][C:14]([S:17][CH3:18])=[C:13]([Cl:19])[CH:12]=1)[CH2:5][C@H:6]1[CH2:10][CH2:9][CH2:8][O:7]1.[OH-].[Li+]>CO>[Cl:19][C:13]1[CH:12]=[C:11]([CH:4]([CH2:5][C@H:6]2[CH2:10][CH2:9][CH2:8][O:7]2)[C:3]([OH:20])=[O:2])[CH:16]=[CH:15][C:14]=1[S:17][CH3:18]A solution of 2-(3-chloro-4-methylsulfanyl-phenyl)-3-(tetrahydro-furan-2(R)-yl)-propionic acid methyl ester (0.519 g, 1.65 mmol) in methanol (7 mL) was treated with a 0.8M aqueous lithium hydroxide solution (40.7 mL, 33.0 mmol). The reaction mixture was stirred at 25° C. for 1.5 h and then concentrated in vacuo to remove methanol. The remaining aqueous layer was acidified to pH=2 with a 10% aqueous hydrochloric acid solution and then extracted with ethyl acetate (2×100 mL). The combined organic layers were washed with a saturated aqueous sodium chloride solution (1×100 mL), dried over sodium sulfate, filtered, and concentrated in vacuo to afford pure 2-(3-chloro-4-methylsulfanyl-phenyl)-3-(tetrahydro-furan-2(R)-yl)-propionic acid (0.495 g, 95.8%) as a light yellow oil that crystallized upon standing: mp 93–96° C.; [α]23589=−23.70° (c=0.46, chloroform); EI-HRMS m/e calcd for C14H17ClO3S (M+) 300.0587, found 300.0579.
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