Oxalyl chloride → (1-(4-[(1-ethyl-5-fluoro-1H-indole-2-carbonyl)amino]-2-fluorobenzyl)-3,5-dimethyl-1H-pyrazol-4-yl)acetic acid methyl ester

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Reaction Steps

To a solution of 1-ethyl-5-fluoro-1H-indole-2-carboxylic acid (140 mg, 0.68 mmol) in 6 mL dichloromethane is added oxalyl chloride (0.094 mL, 0.68 mmol) and a drop dimethylformamide. After stirring at room temperature for 1 hour the solvent is removed by evaporation in vacuo. The residue is dissolved in dichloromethane (5 mL) and dropped to a solution of [1-(4-amino-2-fluorobenzyl)-3,5-dimethyl-1H-pyrazol-4-yl]acetic acid methyl ester (177 mg, 0.61 mmol) and diisopropylethylamine (0.23 mL, 1.35 mmol) in dichloromethane (5 mL). After addition of 4-dimethylaminopyridine (8.255 mg, 0.069 mmol) the solution is stirred at room temperature for 12 hours. The solution is extracted twice with hydrochloric acid (1 M), twice with water, twice with an aqueous solution of NaOH (1 M) and twice with water. The organic layer is dried over MgSO4, filtered and the solvent is evaporated in vacuo. The residue is purified by MPLC (dichloromethane/methanol 95:5) to yield 160 mg of (1-(4-[(1-ethyl-5-fluoro-1H-indole-2-carbonyl)amino]-2-fluorobenzyl)-3,5-dimethyl-1H-pyrazol-4-yl)acetic acid methyl ester (ESI mass spectrum: [M+H]+=481; Retention time HPLC: 0.93 min (method D)). b) To a solution of (1-(4-[(1-ethyl-5-fluoro-1H-indole-2-carbonyl)amino]-2-fluorobenzyl)-3,5-dimethyl-1H-pyrazol-4-yl)acetic acid methyl ester (160 mg, 0.33 mmol) in dioxane (2 mL) is added an aqueous solution of NaOH (1 M, 0.66 mL) and the mixture is stirred at 60° C. for 1 hour. The solvent is evaporated in vacuo, and the residue is suspended in water and treated with acetic acid (2 M). The precipitate is freeze dried, dissolved in methanol and a little dimethylformamide, and the product is precipitated with a little water, filtered and dried to yield 137 mg of the title compound (ESI mass spectrum: [M+H]+=467; Retention time HPLC: 0.89 min (method D)).

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