[CH3:1][O:2][C:3](=[O:12])[CH2:4][C:5]1[C:6]([CH3:11])=[N:7][NH:8][C:9]=1[CH3:10].[F:13][C:14]1[CH:21]=[C:20]([N+:22]([O-:24])=[O:23])[CH:19]=[CH:18][C:15]=1[CH2:16]Br.C([O-])([O-])=O.[K+].[K+]>C(#N)C>[CH3:1][O:2][C:3](=[O:12])[CH2:4][C:5]1[C:9]([CH3:10])=[N:8][N:7]([CH2:16][C:15]2[CH:18]=[CH:19][C:20]([N+:22]([O-:24])=[O:23])=[CH:21][C:14]=2[F:13])[C:6]=1[CH3:11]To a solution of (3,5-dimethyl-1H-pyrazol-4-yl)-acetic acid methyl ester (10 g, 48.9 mmol) and 2-fluoro-4-nitrobenzyl bromide (11.5 g, 49.1 mmol) in acetonitrile (150 mL) is added K2CO3 (10.1 g, 73.3 mmol) and the mixture is stirred for 48 hours at 60° C. The solvent is removed by evaporation and the residue is dissolved in dichloromethane/water. After extraction with dichloromethane the organic layer is dried over Na2SO4 and evaporated under reduced pressure. The residue is purified by MPLC (cyclohexane/diethyl ether 7:3) to yield 13 g of [3,5-dimethyl-1-(2-fluoro-4-nitrobenzyl)-1H-pyrazol-4-yl]acetic acid methyl ester (ESI mass spectrum: [M+H]+=322; Retention time (HPLC): 0.85 min (method C)). b) To a solution of [3,5-dimethyl-1-(2-fluoro-4-nitro-benzyl)-1H-pyrazol-4-yl]acetic acid methyl ester (13 g, 40.4 mmol) in methanol (250 mL) is added Raney nickel (6 g) and the mixture is hydrogenated at 50 psi and 50° C. The catalyst is filtered off and the filtrate is concentrated under reduced pressure. The mixture is purified by crystallization in diisopropyl ether to yield 12.8 g of the title compound (ESI mass spectrum: [M+H]+=292; Retention time HPLC: 0.61 min (method C)).
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