Synthesis
General procedure for the synthesis of tert-butyl 4-(4-bromopyrazol-1-yl)piperidine-1-carboxylate from 4-bromopyrazole and tert-butyl 4-((methylsulfonyl)oxy)piperidine-1-carboxylate: 2.08 kg of cesium carbonate and 0.78 kg of 4-bromopyrazole were dissolved in 4 liters of N-methyl pyrrolidinone, and heated to 80°C. Subsequently, 2.08 kg of cesium carbonate and 0.78 kg of 4-bromopyrazole were dissolved in 5 liters of N-methyl pyrrolidinone. 1.8 kg of tert-butyl 4-((methylsulfonyl)oxy)piperidine-1-carboxylate was added to the reaction mixture and the reaction lasted for 12 hours. After completion of the reaction, it was cooled to room temperature, 50 liters of methyl tert-butyl ether and 50 liters of water were added and stirred for 1 hour. After separating the organic phase, the organic phase was washed 4 times with 20 liters of water, then dried with 50% hexane and stirred for 2 hours at room temperature. Finally, it was filtered and dried to give 1.35 kg of tert-butyl 4-(4-bromopyrazol-1-yl)piperidine-1-carboxylate in 77% yield.
References
[1] Patent: CN106317024, 2017, A. Location in patent: Paragraph 0060; 0061
[2] Journal of Medicinal Chemistry, 2011, vol. 54, # 12, p. 4092 - 4108
[3] Patent: WO2015/81257, 2015, A2. Location in patent: Page/Page column 81
[4] Tetrahedron Letters, 2014, vol. 55, # 9, p. 1528 - 1531
[5] Patent: US2006/46991, 2006, A1. Location in patent: Page/Page column 64-65
