4-(4-Fluorobenzyl)-N-methyl-3-oxopiperazine-1-carboxamide (200 mg, 0.75 mmol) was dissolved in anhydrous DMF (1.5 mL) under nitrogen and chilled to 0° C. in an ice-water bath. Lithium bis(trimethylsilyl)amide (0.91 mL, 0.91 mmol, 1M solution in THF) was added dropwise and then diethyl oxalate (0.15 mL, 1.13 mmol) was immediately added. The reaction was allowed to warm to room temperature and stirred for one hour. The solvent was removed in vacuo and the residue partitioned between aqueous HCl and ethyl acetate. The layers were separated and the aqueous phase was extracted twice more with ethyl acetate. The combined organic extracts were concentrated in vacuo. The residue was triturated with ethyl acetate and the solids were collected by vacuum filtration to yield the title compound as an off-white solid. 1H NMR (400 MHz, d6 DMSO) δ 11.82 (bs, 1H), 7.40 (m, 2H), 7.21 (m, 2H), 4.69 (s, 2H), 3.94 (m, 2H), 3.58 (m, 2H), and 3.21 (s, 3H). HRMS (FT-ICR) C15H14FN3O4+H=320.1047; calculated 320.1041.
