To a stirred mixture of 3-(perfluoroethyl)-1-phenyl-1H-pyrazol-5-amine (300 mg, 1.08 mmol) and potassium carbonate (223 mg, 1.62 mmol) in THF (3 mL) at rt, was added a solution of phenyl chloroformate (169 mg, 1.08 mmol) in THF (2 mL) dropwise. After stirring for a further 15 h at rt, the reaction mixture was filtered and the filtrate concentrated under reduced pressure to give an oil. Purification via silica gel flash column chromatography (eluting with a gradient of 100% petroleum ether to 5% ethyl acetate in petroleum ether) afforded phenyl 3-(perfluoroethyl)-1-phenyl-1H-pyrazol-5-ylcarbamate (360 mg, 84%) as a solid. 1H NMR (400 MHz, CDCl3) δ 7.55-7.62 (m, 5H), 7.39-7.43 (m, 2H), 7.29 (m, 1H), 7.14 (m, 2H), 6.91 (m, 1H); LC-MS (ESI) m/z 398 (M+H)+.
