Triethylamine → tert-Butyl 4-cyanopiperazine-1-carboxylate

1,1-Dimethylethyl 1-piperazinecarboxylate (25 g, 134.2 mmol) was taken into THF (100 mL) followed by addition of triethylamine (25 mL, 178 mmol). The solution was cooled to 0° C. followed by addition dropwise addition of cyanogen bromide (15.6 g, 147.6 mmol) in THF (100 mL) and the resulting mixture was allowed to warm to room temperature then stirred an additional 12 hours. The reaction mixture was concentrated in vacuo and partitioned with ethyl ether and water. The organic layer was washed once with saturated aqueous NaCl then dried over anhydrous magnesium sulfate followed by concentration to afford 1,1-dimethylethyl 4-cyanopiperazine-1-carboxylate (24.5 g, 86% yield) as a colorless crystalline solid. 1H-NMR (400 MHz, CDCl3): 3.51 (tr, 4H), 3.19 (tr, 4H), 1.46 (s, 9H).