Lithium hydroxide, monohydrate → (E)-2-{4-[2-(2-tert-Butoxycarbonylamino-phenylcarbamoyl)-vinyl]-phenyl}-4-(tert-butyl-dimethyl-silanyloxy)-butyric acid

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To a solution of (E)-2-{4-[2-(2-tert-butoxycarbonylamino-phenylcarbamoyl)-vinyl]-phenyl}-4-(tert-butyl-dimethyl-silanyloxy)-butyric acid ethyl ester (2.63 g, 4.52 mmol) in MeOH/H2O (30 mL/10 mL) was added LiOH.H2O (556 mg, 13.56 mmol). This mixture was stirred for about 5 h at room temperature, and then evaporated to remove most of the MeOH. The aqueous layer was acidified with concentrated HCl to pH 5-6. The acidified aqueous layer was extracted with ethyl acetate (3×30 mL). The combined organic layer was washed with brine, dried with Na2SO4, filtered, and evaporated to obtain 2.0 g (80%) of a yellow solid product. MS: calc'd 555 (MH+), exp 555 (MH+).

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