[NH2:1][C:2]1[N:6]([CH3:7])[N:5]=[C:4]([CH3:8])[CH:3]=1.C(N(CC)C(C)C)(C)C.[C:18]([C:26](Cl)=[O:27])(=[O:25])[C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1>C1COCC1.CC(OC)(C)C>[CH3:7][N:6]1[C:2]([NH:1][C:26](=[O:27])[C:18](=[O:25])[C:19]2[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=2)=[CH:3][C:4]([CH3:8])=[N:5]1To a solution of 5-amino-1,3-dimethylpyrazole (2.00 g, 18.0 mmol) in THF (20 mL) was added at ambient temperature N,N-diisopropyl ethyl amine (4.62 mL, 27.0 mmol) and over a period of 5 min benzoylformic acid chloride (which might be prepared according to Synlett (11) 1763-1765, 1999, 3.64 g, 21.6 mmol) and the reaction mixture was stirred for 18 h at this temperature. It was diluted with TBME (50 mL) and washed twice with water (50 mL) and brine (50 mL). The combined aqueous layers were extracted with TBME (50 mL) and the combined organic layers were dried over sodium sulfate. Concentration and purification by chromatography (SiO2, heptane:ethyl acetate=50:50 to 0:100) afforded the title compound (2.11 g, 48%) as a light brown oil. MS m/e: 244.3 [M+H]+.
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