Isopropyl iodide → 4-iodo-1-isopropyl-5-(2-thienyl)-1H-pyrazole

Participants

Reaction Steps

To a solution of 4-iodo-3-(2-thienyl)-1H-pyrazole (1.1 mmol) in 3 mL dry N,N-dimethylformamide under argon atmosphere was added sodium hydride (1.3 mmol, 60% dispersion in mineral oil) in portions. The reaction mixture was stirred at room temperature, then isopropyl iodide (1.7 mmol) was added dropwise. After 2 h at room temperature, water and MTBE were added to the reaction mixture. The phases were separated and the aqueous phase was extracted with MTBE. The combined organic extracts were successively washed with water and brine, dried over MgSO4, filtered and concentrated to afford 350 mg of a mixture of 4-iodo-1-isopropyl-3-(2-thienyl)-1H-pyrazole and 4-iodo-1-isopropyl-5-(2-thienyl)-1H-pyrazole (75:25; 99% yield). The mixture was purified by chromatography on silica gel (cyclohexane:ethyl acetate 100:0 to 0:100) to afford 151 mg 4-iodo-1-isopropyl-3-(2-thienyl)-1H-pyrazole (42% yield) and 42 mg of 4-iodo-1-isopropyl-5-(2-thienyl)-1H-pyrazole (11% yield).

Provenance & Evidence