反应详情

NIS (8.83 g, 39.2 mmol) and TFA (0.825 mL, 10.70 mmol) were added to a stirred solution of ethyl 1H-pyrazole-5-carboxylate (5 g, 35.7 mmol) in CH3CN (120 mL) under Ar. The reaction mixture was stirred for 6 hr at rt, concentrated, diluted with a saturated aqueous solution of NaHCO3, and extracted with EtOAc. The combined organic layers were washed with a saturated aq. NaHCO3 solution, dried over Na2SO4 and evaporated. The crude material was purified by silica gel column chromatography (hexane/EtOAc 10-50%) to afford the title product (8.31 g, 31.2 mmol, 88% yield) as a white solid. tR: 3.47 min (HPLC 1); tR: 0.72 min (LC-MS 2); ESI-MS: 267 [M+H]+ (LC-MS 2); Rf=0.55 (hexane/EtOAc 1:1).

1. concentrationconcentrated
2. additiondiluted with a saturated aqueous solution of NaHCO3
3. extractionextracted with EtOAc
4. washThe combined organic layers were washed with a saturated aq. NaHCO3 solution
5. dry with materialdried over Na2SO4
6. customevaporated
7. customThe crude material was purified by silica gel column chromatography (hexane/EtOAc 10-50%)