General procedure for the synthesis of (5R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethoxazolidin-2-one from phenylmethyl N-(4-bromo-3-fluorophenyl)formate and glycidyl butyrate: 119 g (367 mmol) of phenylmethyl N-(4-bromo-3-fluorophenyl)formate was dissolved in 300 mL of tetrahydrofuran and 150 mL of dimethylformamide mixed solvent and 38.19 g (477 mmol) of lithium tert-butoxide was added slowly dropwise at 0 °C. The reaction solution was stirred for 10 min, then 63 mL (440 mmol) of (R)-glycidyl butyrate and 21 mL (550 mmol) of methanol were added, and the resulting solution continued to be stirred for 3 h at room temperature. Upon completion of the reaction, the pH of the reaction mixture was adjusted to about 6 with aqueous ammonium chloride, followed by concentration under reduced pressure. The concentrate was dissolved in 1000 mL of 80% ethyl acetate/hexane mixed solvent, washed sequentially with water and saturated aqueous sodium chloride solution (brine), and the organic phase was dried over anhydrous sodium sulfate. After removal of the solvent under reduced pressure, purification by column chromatography afforded 93 g (320 mmol) of (5R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethoxazolidin-2-one as a white solid (yield: 87%).1H NMR (600 MHz, CDCl3) δ 7.53 (m, 2H), 7.15 (dd, J1 = 9.0 Hz, J2 = 2.4 Hz, 1H), 4.77 (m, 1H), 4.00 (m, 3H), 3.77 (m, 1H), 2.10 (t, J = 6.0 Hz, 1H).
