Trifluoroacetic acid → 4-{(S)-4-Carboxy-2-[(5-{2-[(S)-2-(3-cyclopropyl-[1,2,4]oxadiazol-5-yl)-pyrrolidin-1-yl]-2-oxo-ethoxy}-1-phenyl-1H-pyrazole-3-carbonyl)-amino]-butyryl}-piperazine-1-carboxylic acid ethyl ester

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Reaction Steps

To a solution of 213 mg 4-{(S)-4-tert-Butoxycarbonyl-2-[(5-carboxymethoxy-1-phenyl-1H-pyrazole-3-carbonyl)-amino]-butyryl}-piperazine-1-carboxylic acid ethyl ester in 7 ml DMF were added 138 mg HATU, 50 mg HOAT, 0.19 ml DIPEA and 65 mg 3-Cyclopropyl-5-(S)-pyrrolidin-2-yl-[1,2,4]oxadiazole. It was concentrated, the residue dissolved in dichloromethane and extracted with aqueous LiCl (4% w/w), aqueous NaHCO3 and 0.1 M HCl. The organic layer was dried over MgSO4 and concentrated to furnish the crude coupling product as colorless oil. The latter one was dissolved in 10 ml DCM and treated with 403 μl TFA. After stirring for 12 h the solvents were removed under reduced pressure and the residue purified by preparative HPLC (C18 reverse phase column, elution with a water/MeCN gradient with 0.1% TFA) to give the title compound.

Provenance & Evidence