Cl.[CH3:2][CH:3]([O:5][C:6]1[CH:11]=[CH:10][C:9]([C:12]2[C:16]([CH:17]=[O:18])=[CH:15][NH:14][N:13]=2)=[CH:8][CH:7]=1)[CH3:4].[C:19]([O-])([O-])=O.[K+].[K+].CI.O>C(#N)C>[CH:3]([O:5][C:6]1[CH:11]=[CH:10][C:9]([C:12]2[C:16]([CH:17]=[O:18])=[CH:15][N:14]([CH3:19])[N:13]=2)=[CH:8][CH:7]=1)([CH3:2])[CH3:4]A mixture of 3-[4-(propan-2-yloxy)-phenyl]-1H-pyrazole-4-carbaldehyde hydrochloride (400 mg, 1.5 mmol) and K2CO3 (624 mg, 4.5 mmol) in acetonitrile (6 mL) was stirred at 0-5° C. for 1 h. Methyl iodide (310 mg, 2.2 mmol) was added and the mixture stirred at ambient temperature for 48 h. The reaction was poured into water (200 mL) and extracted with EtOAc (50 mL×3). The combined extracts were washed with brine (100 mL), dried, and concentrated under vacuum. The residue was purified by prep-TLC using Hexane:EtOAc (210:90) as eluent to afford the 3-(4-isopropoxyphenyl)-1-methyl-1H-pyrazole-4-carbaldehyde (82 mg, Yield: 19%) as a white solid. 1H NMR (400 MHz, CDCl3): δ 9.94 (s, 1H), 8.00 (s, 1H), 7.68-7.64 (m, 2H), 7.02-6.97 (m, 2H), 4.69-4.59 (t, J=6.0 Hz, 1H), 4.00 (s, 3H), 1.38 (d, J=6.0 Hz, 6H) ppm. LCMS (method C RT=2.08 min, m/z=245.2 [M+H]+.
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