Step 1: Synthesis of tert-butyl 4-(6-chloropyrimidin-4-yl)piperazine-1-carboxylate
In a microwave reaction tube, 4,6-dichloropyrimidine (0.5 g, 3.36 mmol), N-BOC-piperazine (0.69 g, 3.36 mmol) and triethylamine (0.34 g, 3.36 mmol) were dissolved in acetonitrile (10 mL). The reaction mixture was microwaved at 120 °C for 2 hours. After completion of the reaction, the mixture was diluted with ethyl acetate, washed sequentially with saturated ammonium chloride solution and dried over anhydrous magnesium sulfate. The drier was removed by filtration and the filtrate was concentrated under reduced pressure to afford the target compound tert-butyl 4-(6-chloropyrimidin-4-yl)piperazine-1-carboxylate (0.82 g, 91% yield).
1H NMR (500MHz, CDCl3): δ 8.39 (s, 1H), 6.50 (s, 1H), 3.65 (m, 4H), 3.52 (m, 4H), 1.48 (s, 9H).