[Cl:1][C:2]1[CH:3]=[C:4]([CH2:10][C:11]([OH:13])=[O:12])[CH:5]=[CH:6][C:7]=1[S:8][CH3:9].[CH3:14][Si]([N-][Si](C)(C)C)(C)C.[Li+].CI.C(OCC)(=O)C.CCCCCC>C1COCC1>[Cl:1][C:2]1[CH:3]=[C:4]([CH:10]([CH3:14])[C:11]([OH:13])=[O:12])[CH:5]=[CH:6][C:7]=1[S:8][CH3:9]2-(3-chloro-4-(methylthio)phenyl)acetic acid (2 g, 0.009 mol) was taken in THF (20 mL, 10 times) and cooled to −78° C. Lithium bis(trimethylsilyl)amide (27.77 mL, 3 eq) was added drop wise at −78° C. and allowed to stir for 2 h at the same temperature. Then methyl iodide (1.31 g, 1 eq) was added drop wise at −78° C. and the overall reaction mass was allowed to stir for 3 h at the same temperature. Progress of the reaction was monitored by TLC (50% ethyl acetate/hexane, Rf˜0.2). As the reaction was not completed, reaction mass was warmed to room temperature and allowed to stir for 10 h. Again TLC was monitored and still the reaction was not completed. Then the reaction contents were quenched with saturated ammonium chloride solution and acidified with diluted HCl. THF layer was separated and the aqueous layer was extracted with ethyl acetate (2×50 mL). The combined extract was dried over sodium sulfate, concentrated under reduced pressure and the crude product obtained was purified by column chromatography (10% ethyl acetate/n-hexane) to yield 2-(3-chloro-4-(methylthio)phenyl)propanoic acid as a pale yellow colored solid (1.2 g, 53%).
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