To a stirred solution of tert-butyl 4-(5-iodopyridin-2-yl)piperazine-1-carboxylate (1.0 g, 2.57 mmol, prepared as in Example 1), trimethylsilyl acetylene (0.73 mL, 5.14 mmol), triethylamine (1.11 mL, 7.71 mmol), and cuprous iodide (196 mg, 1.03 mmol) in DMA (20 mL) at 25° C. was added tetrakistriphenylphosphine palladium (0) (149 mg, 5 mol %). The reaction was stirred for 10 minutes. Volatiles were removed in vacuo. The residue was then dissolved in ethyl acetate (250 mL) and washed with water (100 mL). The layers were then separated and the aqueous phase extracted with ethyl acetate (250 mL). The combined organic extracts were then dried, (MgSO4), filtered and concentrated in vacuo. The residue was then purified by flash chromatography (silica gel, 10% EtOAc in hexanes) to give tert-butyl 4-{5-[(trimethylsilyl)ethynyl]pyridin-2-yl}piperazine-1-carboxylate as a pale brown solid (652 mg, 1.81 mmol, 70%).
