Br[C:2]1[CH:3]=[N:4][N:5]([C:7]2[CH:12]=[CH:11][C:10]([O:13][CH3:14])=[CH:9][CH:8]=2)[CH:6]=1.C([Li])CCC.CCCCCC.CN(C)[CH:28]=[O:29]>O1CCCC1>[CH3:14][O:13][C:10]1[CH:11]=[CH:12][C:7]([N:5]2[CH:6]=[C:2]([CH:28]=[O:29])[CH:3]=[N:4]2)=[CH:8][CH:9]=1To a −78° C. solution of 4-bromo-1-(4-methoxyphenyl)-1H-pyrazole (506 mg, 2.0 mmol) in anhydrous tetrahydrofuran (20 mL) was added n-butyllithium in hexane (0.95 mL, 2.4 mmol). The reaction was stirred for 2 h at −78° C. N,N-dimethylformamide (292 mg, 4 mmol) was added and the reaction continued to stir at −78° C. for 1 h, then at room temperature for 2 h. The reaction was quenched with saturated ammonium chloride (20 mL) and extracted with ethyl acetate (3×30 mL). The combined organics were washed with brine (30 mL), dried over sodium sulfate, filtered and concentrated. Purification by column chromatography gave 1-(4-methoxyphenyl)-1H-pyrazole-4-carbaldehyde (80 mg, 20%) as a yellow oil. 1H NMR (400 MHz, CDCl3, δ): 9.95 (s, 1H), 8.33 (s, 1H), 8.13 (s, 1H), 7.62 (d, J=9.2 Hz, 2H), 7.01 (d, J=9.2 Hz, 2H), 3.86 (s, 3H).
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