Br[C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[N:7]([CH3:11])[N:6]=[CH:5]2.C([Li])CCC.[C:17](OCC)(=[O:23])[C:18]([O:20][CH2:21][CH3:22])=[O:19]>C1COCC1>[CH3:11][N:7]1[C:8]2[C:4](=[CH:3][C:2]([C:17](=[O:23])[C:18]([O:20][CH2:21][CH3:22])=[O:19])=[CH:10][CH:9]=2)[CH:5]=[N:6]1To a solution of 5-bromo-1-methyl-1H-indazole (Aldrich, 1.06 g, 5 mmol) in THF (22 mL) at −78° C. was added n-butyllithium (2.2 mL, 2.5 M, 5.5 mmol) slowly. The mixture was stirred for 20 minutes, and the solution of diethyl oxalate (0.68 mL, 5.0 mmol) in THF (5 mL) was added over one minute period. The reaction was kept at −78° C. for 40 minutes, and was quenched with saturated ammonium chloride solution and warmed to 25° C. The mixture was extracted with ethyl acetate, and the organic phase was washed with water, brine, and dried over sodium sulfate. Concentration and purification with flash column chromatography (hexanes/EtOAc) gave ethyl 2-(1-methyl-1H-indazol-5-yl)-2-oxoacetate. LCMS-ESI+: calc'd for C12H13N2O3: 233.2 (M+H+); Found: 233.0 (M+H+).
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