110-87-2

3469-69-0

938066-17-2

To a stirred solution of 4-iodopyrazole (5.0 g, 25.8 mmol) in dichloromethane (10 mL) was sequentially added p-toluenesulfonic acid monohydrate (TsOH-H2O, 0.5 g, 2.9 mmol) and 3,4-dihydro-2H-pyran (4.5 g, 53.5 mmol). The reaction mixture was stirred at room temperature for 2 hours. After completion of the reaction, the mixture was concentrated under reduced pressure to remove the solvent. The crude product was purified by silica gel column chromatography using ethyl acetate/petroleum ether (1:3, v/v) as eluent to afford the target compound, 4-iodo-1-(tetrahydropyran-2-yl)-1H-pyrazole (7 g, 93% yield), as a colorless oil.The LC-MS (ESI) analysis showed [M-84 + H]+ = 195.1 .