[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[CH:12]=[C:11]([CH3:13])[NH:10][N:9]=2)=[CH:4][CH:3]=1.[H-].[Na+].[CH3:16][O:17][C:18](=[O:25])[CH2:19][CH2:20][C:21](=[O:24])[CH2:22]Br.O>CN(C)C=O>[CH3:16][O:17][C:18](=[O:25])[CH2:19][CH2:20][C:21](=[O:24])[CH2:22][N:10]1[C:11]([CH3:13])=[CH:12][C:8]([C:5]2[CH:4]=[CH:3][C:2]([Cl:1])=[CH:7][CH:6]=2)=[N:9]1
3-(4-Chloro-phenyl)-5-methyl-1H-pyrazole (1.84 g, 9.6 mmol) was dissolved in dimethylformamide (20 ml) followed by the addition of sodium hydride (60% dispersion in oil, 384 mg, 9.6 mmol). The reaction was stirred at room temperature for 15 min, followed by the addition of 5-bromo-4-oxo-pentanoic acid methyl ester (2 g, 9.6 mmol). The reaction was stirred at room temperature for a further 30 min, before the addition of water (200 ml). The solution was then extracted with ethyl acetate (2×150 ml). The organics were dried over magnesium sulfate and concentrated in vacuo. The crude product was then purified by column chromatography (120g column, DCM to 90% DCM/EtOAc over 50 mins) to give 5-[3-(4-chloro-phenyl)-5-methyl-pyrazol-1-yl]-4-oxo-pentanoic acid methyl ester (1.84 g).
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