C[N:2]1[CH:6]=[CH:5][C:4]([C:7]([O:9][CH2:10][CH3:11])=[O:8])=[N:3]1.[I:12]I.O=[N+]([O-])[O-].[O-][N+](=O)[O-].[O-][N+](=O)[O-].[O-][N+](=O)[O-].[O-][N+](=O)[O-].[O-][N+](=O)[O-].[Ce+4].[NH4+].[NH4+]>CC#N>[I:12][C:5]1[C:4]([C:7]([O:9][CH2:10][CH3:11])=[O:8])=[N:3][NH:2][CH:6]=1To a stirred solution of ethyl 1-methyl-1H-pyrazole-3-carboxylate (5 g, 32.4 mmol) in CH3CN (200 mL) under Ar was added I2 (4.94 g, 19.46 mmol) and after 5 min CAN (10.67 g, 19.46 mmol). The reaction mixture was stirred for 1 hr at 80° C., concentrated, quenched with a 10% aq. Na2S2O3 solution, and extracted with CH2Cl2. The combined organic layers were washed with brine, dried over Na2SO4 and evaporated. The crude material was purified by silica gel column chromatography (hexane/EtOAc 25-45%) to afford the title product (9.04 g, 32.3 mmol, 100% yield) as a white solid. tR: 3.78 min (HPLC 1); tR: 0.80 min (LC-MS 2); ESI-MS: 281 [M+H]+ (LC-MS 2); Rf=0.45 (hexane/EtOAc 1:1).
Wird geladen…
