Step 1: Suspend 4-iodo-1H-pyrazole (3.0 g) in benzene (150 mL), stir and heat the suspension. Ethyl vinyl ether (4.4 mL) was slowly added, followed by dropwise addition of concentrated hydrochloric acid, with continuous stirring at 60 °C for 3 hours. Upon completion of the reaction, the reaction mixture was concentrated under reduced pressure and the residue was neutralized with saturated aqueous sodium bicarbonate (10 mL). The mixture was extracted with ethyl acetate (50 mL) and the extract was washed sequentially with distilled water (100 mL). The organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to afford the target compound 1-(1-ethoxyethyl)-4-iodo-1H-pyrazole as a clear yellow liquid (3.0 g, 73% yield). 1H NMR (CDCl3): δ 7.54 (s, 1H), 7.41 (s, 1H), 5.40 (q, 1H, J = 6.0Hz), 3.38-3.18 (m, 2H), 1.54 (d, 3H, J = 6.0Hz), 1.05 (t, 3H, J = 7.1Hz).
