1-(4-BOC-piperidyl)-4-iodopyrazole is prepared by the reaction of 4-Iodopyrazole and 1-Boc-4-methanesulfonyloxypiperidine. The specific synthesis steps are as follows:
To a stirred solution of 4-iodo-lH-pyrazole (8.98 g, 46.28 mmol) in DCM (160 mL) was added NaH (1.67 g, 55.53 mmol, 80percent NaH/mineral oil) portion-wise at 0 °C. The mixture was stirred at 0 °C for 1 hour, then tert-butyl 4-((methylsulfonyl)oxy)piperidine-l- carboxylate (14.22 g, 50.90 mmol) was added. The resulted mixture was stirred at 100 °C for 15 hours, then cooled to rt, quenched with H20 (30 mL) and concentrated in vacuo. The residue was diluted with H20 (150 mL), and the mixture was extracted with EtOAc (100 mL x 5). The combined organic layers were dried over anhydrous Na2S04 and concentrated in vacuo. The residue was purified by a silica gel column chromatography (PE/EtOAc (v/v) = 5/1) to give 1-(4-BOC-piperidyl)-4-iodopyrazole as a white solid (12.25 g, 70.2percent>). MS (ESI, pos. ion) m/z: 322.0 (M-56+1).
