Water → [3,5-Dimethyl-1-(4-nitro-benzyl)-1H-pyrazol-4-yl]-acetic acid methyl ester

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Reaction Steps

To a solution of (3,5-dimethyl-1H-pyrazol-4-yl)acetic acid methyl ester (3.90 g, 23 mmol) and 4-nitrobenzyl bromide (4.60 g, 20.7 mmol) in acetonitrile is added K2CO3 (2.76 g, 19.9 mmol) and the mixture is stirred for one hour at room temperature. The reaction mixture is poured into water and extracted twice with ethyl acetate. The organic phase is dried over MgSO4 and evaporated under reduced pressure. To yield 7.50 g of [3,5-Dimethyl-1-(4-nitro-benzyl)-1H-pyrazol-4-yl]-acetic acid methyl ester (ESI mass spectrum: [M+H]+=304). b) To a solution of [3,5-dimethyl-1-(4-nitrobenzyl)-1H-pyrazol-4-yl]acetic acid methyl ester (3.90 g, 10.3 mmol) in methanol (10 mL) is added 10% palladium on charcoal (500 mg) and the mixture is hydrogenated. The catalyst is filtered off and the filtrate is concentrated under reduced pressure. The mixture is purified via preparative reversed phase HPLC (gradient of methanol in water+0.1% NH3) to yield 1.18 g of the title compound (ESI mass spectrum: [M+H]+=274; Retention time HPLC: 2.13 min (method A))

Provenance & Evidence