Sodium Carbonate → [3-(2-Triisopropylsilyloxy-ethoxy)-5-hydroxy-phenyl]-acetic acid methyl ester

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A mixture of 9.39 g (51.5 mmol) of (3,5-dihydroxy-phenyl)-acetic acid methyl ester (prepared according to U. Eder, G. Sauer, G. Haffer, G. Neef, R. Wiechert, U.S. Pat. No. 4,066,674), 11.38 g (61.8 mmol) of 1-bromo-2-triisopropylsilyloxy-ethane and 14.50 g (51.5 mmol) of cesium carbonate is stirred at RT for 1 hour and at 60° C. for another hour. The reaction mixture is then treated with saturated aqueous sodium carbonate and extracted with ethyl acetate. The layers are separated and the organic layer is washed three times with saturated aqueous sodium carbonate. The aqueous layers are combined and extracted three times with ethyl acetate. The combined organic solutions are then washed with saturated brine, dried, filtered and concentrated under reduced pressure. The residue is purified by column chromatography on silica gel (85:15 hexane/ethyl acetate then 70:30 hexane/ethyl acetate and finally pure ethyl acetate) to afford above title compound as a yellow oil. MS (EI, negative ionization) m/z 381 [M−H]−, (EI, positive ionization) m/z 405 [M+Na]+

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