[CH3:1][O:2][C:3](=[O:21])/[C:4](/[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][C:8]=1[O:13][C:14]1[CH:19]=[CH:18][C:17]([CH3:20])=[CH:16][CH:15]=1)=[N:5]/[OH:6].[H-].[Na+].[CH3:24]OS(OC)(=O)=O.Cl>O1CCCC1.O>[CH3:1][O:2][C:3](=[O:21])/[C:4](/[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][C:8]=1[O:13][C:14]1[CH:15]=[CH:16][C:17]([CH3:20])=[CH:18][CH:19]=1)=[N:5]/[O:6][CH3:24]E-α-hydroxyimino-2-(4-methylphenoxy)pheylacetic acid methyl ester (0.71 g, 0.0025 mole) was dissolved in dried tetrahydrofuran (10 ml), followed by the addition of 60% sodium hydride (0.13 g, 0.033 mole). Then, the mixture was stirred at room temperature for 20 minutes and to this was added dropwise a solution of dimethylsulfate (0.44 g, 0.0035 mole) dissolved in dried THF (2.5 ml) under ice cooling, followed by stirring for 1.75 hours under ice cooling. After completion of the reaction, water was added to the reaction mixture which was adjusted to pH 1 with conc. hydrochloric acid. The mixture was extracted twice with methylene chloride, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting residue was purified by silica gel chromatography (ethyl acetate/n-hexane) to obtain E-α-methoxyimino-2-(4-methylphenoxy)phenylacetic acid methyl ester (0.61 g, yield: 81.3%) as a colorless oil.
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