Ethyl bromoacetate → (S)-(+)-2-Oxo-4-phenyl-3-oxazolidineacetic acid

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Reaction Steps

To a stirred, 0° C. solution of (S)-4-phenyloxazoldin-2-one (1.07 g, 6.54 mmol) in 15 mL of THF was added sodium hydride (0.32 g of a 60% oil dispersoin, 8.0 mmol). When gas evolution had ceased (ca. 10 minutes), ethyl bromoacetate (0.87 mL, 7.8 mmol) was added. After 2 hours at 0° C., the mixture was treated with 50 mL of 2N aqueous NaOH, stirred rapidly for 1 hour at room temperature, and then partitioned between hexane (50 mL) and water (50 mL). The aqueous layer was separated, acidified with 6M aqueous H2SO4, and extracted with dichloromethane (2×200 mL). The combined organic phases were dried (Na2SO4) and concentrated to a thick oil, which was dissolved in 4 mL of warm toluene, seeded, and allowed to crystallize overnight; filtration gave 1.33 g (92%) of (S)-4-phenyloxazolidin-2-one-3-ylacetic acid: mp 106°-108° C.;

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