3-Oxo-1-piperazinecarboxylic acid 1,1-dimethylethyl ester (0.200 g, 0.999 mmol) and 1-bromo-4-fluorobenzene (0.091 mL, 0.832 mmol) were added with copper(I) iodide (0.008 g, 0.042 mmol), potassium carbonate (0.230 g, 1.665 mmol) and N,N'-dimethyl- 1,2-ethylenediamine (0.009 mL, 0.083 mmol) in toluene (5 mL). The mixture was heated to reflux overnight under nitrogen protection. Upon completion of the reaction, the reaction mixture was filtered through a pad of silica gel. The filtrate was concentrated and the resulting residue was purified by silica gel column chromatography (eluent: ethyl acetate/hexane) to afford 4-(4-fluorophenyl)-3-oxo-1-piperazinecarboxylic acid 1,1-dimethylethyl ester (0.180 g, 73% yield) as a white solid.
