Cesium carbonate → 4-Iodo-1-(2,2,2-trifluoroethyl)-1H-pyrazole

In a microwave vial 4-iodo-1H-pyrazole (1.00 g, 5.16 mmol) and cesium carbonate (6.72 g, 20.6 mmol) were suspended in DMF (8.0 mL) and 1,1,1-trifluoro-2-iodoethane (2.06 mL, 20.6 mmol) was added. The mixture was heated at 90° C. by microwave for 60 minutes then the mixture was filtered and the filter cake rinsed with EtOAc. The filtrate was concentrated then taken up in EtOAc and 50% saturated aqueous NH4Cl. The organic layer was washed with sat LiCl and sat NaCl then dried over MgSO4. The solution was concentrated and the residue purified by SiO2 chromatography (5-35% EtOAc/heptane) to afford 1.08 g (76%) of 4-iodo-1-(2,2,2-trifluoroethyl)-1H-pyrazole as a colorless oil.