(4S,5R)-(−)-4-Methyl-5-phenyl-2-oxazolidinone (0.062 g, 0.35 mmol) was added to a vial containing sodium hydride (60% in mineral oil; 0.015 g, 0.38 mmol) in 1,4-dioxane (10 mL). After stirring for 30 minutes at room temperature, the mixture was added to a vial containing [5-(4-bromo-2-bromomethyl-phenoxy)-2-chloro-phenyl]-acetic acid ethyl ester (0.15 g, 0.32 mmol) at 10° C. The reaction was stirred at room temperature overnight, and then additional (4S,5R)-(−)-4-methyl-5-phenyl-2-oxazolidinone (0.062 g, 0.35 mmol), pretreated with sodium hydride (60% in mineral oil; 0.015 g, 0.38 mmol), was added and the reaction was stirred overnight. Once no starting material was observed by analytical LCMS, the mixture was carried forward to the hydrolysis step.
