C([O:3][C:4]([C:6]1([CH2:10][NH:11][C:12]2[CH:13]=[N:14][CH:15]=[C:16]([C:18]3[N:19]([CH3:27])[C:20]4[C:25]([CH:26]=3)=[CH:24][CH:23]=[CH:22][CH:21]=4)[CH:17]=2)[CH2:9][CH2:8][CH2:7]1)=[O:5])C.[OH-].[Li+]>C1COCC1.CO>[CH3:27][N:19]1[C:20]2[C:25](=[CH:24][CH:23]=[CH:22][CH:21]=2)[CH:26]=[C:18]1[C:16]1[CH:17]=[C:12]([NH:11][CH2:10][C:6]2([C:4]([OH:5])=[O:3])[CH2:9][CH2:8][CH2:7]2)[CH:13]=[N:14][CH:15]=1To a solution of 1-{[5-(1-methyl-1H-indol-2-yl)-pyridin-3-ylamino]-methyl}-cyclobutanecarboxylic acid ethyl ester (0.107 g, 0.288 mmol) in THF (2 mL) and methanol (1 mL) is added aqueous lithium hydroxide (1M, 0.58 mL, 0.58 mmol) and the solution is stirred overnight. The product is isolated by RP HPLC on an Xbridge C18 eluting with an acetonitrile in 0.1% aqueous NH4OH gradient to give 1-{[5-(1-methyl-1H-indol-2-yl)-pyridin-3-ylamino]-methyl}-cyclobutanecarboxylic acid as a white powder. 1H NMR (400 MHz, DMSO-d6) δ ppm 1.74-1.86 (m, 1H), 1.87-1.97 (m, 3H), 2.26-2.35 (m, 2H), 3.33 (br. s., 1H), 3.39 (s, 2H), 3.75 (s, 3H), 6.60 (s, 1H), 7.05-7.09 (m, 1H), 7.15 (m, 1H), 7.17-7.21 (m, 1H), 7.50 (d, J=8.3 Hz, 1H), 7.57 (d, J=7.7 Hz, 1H), 7.94 (d, J=1.8 Hz, 1H), 8.06 (d, J=2.7 Hz, 1H). MS (ESI) m/z 336 (M+H)+.
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