4-(5-Cyano-2-pyridin-3-yl-indole-1-carbonyl)-benzoic acid tert-butyl ester → 4-(5-Cyano-2-pyridin-3-yl-indole-1-carbonyl)-benzoic acid

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Reaction Steps

4-(5-Cyano-2-pyridin-3-yl-indole-1-carbonyl)-benzoic acid tert-butyl ester (100 mg) is dissolved in TFA (3 mL) and stirred at ambient temperature for 1 h. The solvent is removed in vacuo and the residue is triturated with diethyl ether twice. The residue is purified by reverse phase HPLC with Sunfire C18 and a gradient of acetonitrile in 0.1% aqueous TFA to afford 4-(5-cyano-2-pyridin-3-yl-indole-1-carbonyl)-benzoic acid as a white solid. 1H NMR (400 MHz, DMSO-d6) δ ppm (TFA salt) 7.24 (s, 1H), 7.28 (dd, J=7.9, 4.9 Hz, 1H), 7.73-7.77 (m, 4H), 7.81 (dt, J=8.1, 1.9, 1.8 Hz, 1H), 7.87-7.91 (m, 2H), 8.32 (t, J=1.1 Hz, 1H), 8.41 (dd, J=4.9, 1.6 Hz, 1H), 8.63-8.65 (m, 1H), 13.40 (br. s., 1H). HRMS (ESI) m/z 366.0868 [(M+H)+ Calcd for C22H14N3O3: 366.0879].

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