34091-51-5

930-36-9

34091-51-5

Under nitrogen protection, 1-methylpyrazole (6.00 g) was dissolved in tetrahydrofuran (120 mL) and n-butyllithium (39.0 mL, 2.6 M hexane solution) was slowly added dropwise. After the dropwise addition, the reaction solution was stirred for 30 minutes. Subsequently, the reaction solution was cooled in an ice bath and stirred for 1 hour. Next, the temperature of the reaction solution was lowered to -78°C and a tetrahydrofuran (50 mL) solution of iodine (28.0 g) was slowly added dropwise. After the dropwise addition was completed, the reaction solution continued to be stirred at -78 °C for 1 hour. Afterwards, the reaction solution was allowed to slowly warm to room temperature and stirred overnight. Upon completion of the reaction, 30% aqueous sodium thiosulfate was added to the reaction solution to quench the reaction, followed by distillation under reduced pressure to remove the solvent. The residue was extracted with ethyl acetate and the organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The dried organic layer was concentrated under reduced pressure and the solid obtained was washed with n-hexane to give the final 5-iodo-1-methyl-1H-pyrazole (11.4 g) in the form of a maroon solid. The product was characterized by 1H NMR (200 MHz, chloroform-d): δppm 3.94 (s, 3H), 6.43 (d, J = 2.20 Hz, 1H), 7.47 (d, J = 1.76 Hz, 1H); mass spectrum (ESI pos.) m/z 209 [M + H]+.