A mixture of tert-butyl 4-(5-bromopyrimidin-2-yl)piperazine-1-carboxylate (684 mg, 2.0 mmol), 2-fluorophenol (1.1 g, 10.0 mmol), copper (650 mg, 10.0 mmol) and cesium carbonate (6.5 g, 20.0 mmol) in pyridine (15 mL) was heated at 120 0° C. in a sealed tube overnight. The reaction mixture was diluted with ethyl acetate (200 mL) and then filtered. The filtrate was concentrated, and the residue was purified by silica gel chromatography (petroleum ether:ethyl acetate 20:1) to give tert-butyl 4-(5-(2-fluorophenoxyl)pyrimidin-2-yl)piperazine-1-carboxylate (50 mg, 6%) as a yellow solid. MS (ES+) C19H23FN4O3 requires: 374, found: 397 [M+Na]+.
