[CH3:1][C:2]1[C:6]([C:7]([O:9][CH2:10][CH3:11])=[O:8])=[CH:5][NH:4][N:3]=1.C(=O)([O-])[O-].[K+].[K+].[Cl:18][C:19]1[N:24]=[C:23](Cl)[CH:22]=[CH:21][N:20]=1>CN(C)C=O>[Cl:18][C:19]1[N:24]=[C:23]([N:4]2[CH:5]=[C:6]([C:7]([O:9][CH2:10][CH3:11])=[O:8])[C:2]([CH3:1])=[N:3]2)[CH:22]=[CH:21][N:20]=1To a solution of ethyl 3-methyl-1H-pyrazole-4-carboxylate (6.0 g, 38.9 mmol) in 50 mL of anhydrous N,N-dimethylformamide (DMF) were added potassium carbonate (10.8 g, 77.8 mmol) and 2,4-dichloropyrimidine (5.8 g, 38.9 mmol) at room temperature. The resulting suspension was stirred for 8 hours with monitoring a reaction with LC-MS or thin layer chromatography (TLC). Volatiles were removed and the residue was extracted with dichloromethane. The collected organic layer was washed with brine, dried over anhydrous sodium sulfate and then concentrated in vacuo. The resulting residue was purified by silica gel chromatography using a mixture of heptanes and ethyl acetate to afford the desired intermediate 1 as a white solid (5.45 g, 52%); MS (ESI) m/z 267 [M+H]+, 1H NMR (300 MHz, CDCl3) δ 8.99 (s, 1H), 8.68 (d, 1H, J=5.4 Hz), 7.86 (d, 1H, J=5.4 Hz), 4.35 (q, 2H, J=7.2 Hz), 2.57 (s, 3H), 1.40 (t, 3H, J=7.2 Hz).
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