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温度

0 °C

A mixture of compound tert-butyl piperazine-1-carboxylate (3.725 g, 20 mmol) and potassium carbonate (5.53 g, 40 mmol) in anhydrous dichloromethane (30 mL) was cooled to 0° C., cyclopropanecarbonyl chloride (2.30 g, 22 mmol) was then added dropwise. After the addition, the mixture was stirred at room temperature overnight. The mixture was diluted with dichloromethane (100 mL), washed with 10% citric acid (50 mL), followed by saturated sodium bicarbonate (50 mL), brine (100 mL), dried over anhydrous sodium sulfate, and concentrated to give tert-butyl 4-(cyclopropanecarbonyl)piperazine-1-carboxylate (3.7 g, yield 73%) as a white solid. 1H-NMR (400 MHz, CDCl3) δ (ppm): 0.76-0.81 (m, 2H), 0.98-1.03 (m, 2H), 1.49 (s, 9H), 1.69-1.75 (m, 1H), 3.46-3.48 (m, 4H), 3.63-3.65 (m, 4H); LC-MS (ESI) m/z: 255 (M+1)+.

1. additionAfter the addition
2. washwashed with 10% citric acid (50 mL)
3. dry with materialdried over anhydrous sodium sulfate
4. concentrationconcentrated