反应详情

To a solution of isobutyric acid (6.608 g, 75 mmol) in anhydrous dichloromethane (130 mL) was added triethylamine (8.33 g, 82.5 mmol), 1-hydroxybenzotriazole (10.125 g, 75 mmol), followed by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (14.25 g, 75 mmol). After the addition, the mixture was stirred at room temperature for 40 mins. Then the mixture was cooled to 0° C., and tert-butyl piperazine-1-carboxylate (13.97 g, 75 mmol) was added portion-wise. After the addition, the mixture was stirred at room temperature overnight. The mixture was diluted with dichloromethane (200 mL), washed with saturated sodium bicarbonate (150 mL×2), 10% citric acid (150 mL), brine (100 mL), dried over anhydrous sodium sulfate, and concentrated to give tert-butyl 4-isobutyrylpiperazine-1-carboxylate (15 g, yield 78%) as a white solid. 1H-NMR (400 MHz, CDCl3) δ (ppm): 1.13-1.14 (d, J=6.8 Hz, 6H), 1.47 (s, 9H), 2.75-2.82 (m, 1H), 3.43-3.58 (m, 4H); LC-MS (ESI) m/z: 257(M+1)+.

1. additionAfter the addition
2. temperatureThen the mixture was cooled to 0° C.
3. additionAfter the addition
4. stirringthe mixture was stirred at room temperature overnight
5. washwashed with saturated sodium bicarbonate (150 mL×2), 10% citric acid (150 mL), brine (100 mL)
6. dry with materialdried over anhydrous sodium sulfate
7. concentrationconcentrated