2-[2-(4-Fluorophenyl)acetyl]-4-hydroxy-pyrazolidine-1-carboxylic acid benzyl ester, 28, (2.55 g, 7.91 mmol) is dissolved in dimethylformamide (40 mL). Methyl iodide (1.97 mL, 31.6 mmol) is added followed by silver oxide (3.67 g, 15.8 mmol). The flask is cover with foil and stirred overnight in the absence of light. The reaction mixture is poured into ether (150 mL). The mixture is stirred vigorously at room temperature and filtered through a pad of Celite. The filtrate is washed with water (2×150 mL) and brine (150 mL), dried over sodium sulfate, filtered and concentrated in vacuo to afford 2.58 g (97% yield) of the desired product as a yellow, clear oil.
