[OH:1][B:2]1[C:6]2[CH:7]=[CH:8][C:9]([O:11][C:12]3[CH:20]=[CH:19][C:15]([C:16]([OH:18])=[O:17])=[CH:14][CH:13]=3)=[CH:10][C:5]=2[CH2:4][O:3]1.[CH3:21][N:22]([CH2:24][CH2:25]O)[CH3:23].CCN=C=NCCCN(C)C>CN(C=O)C>[CH3:21][N:22]([CH3:23])[CH2:24][CH2:25][O:17][C:16](=[O:18])[C:15]1[CH:14]=[CH:13][C:12]([O:11][C:9]2[CH:8]=[CH:7][C:6]3[B:2]([OH:1])[O:3][CH2:4][C:5]=3[CH:10]=2)=[CH:20][CH:19]=1To a clear solution of 4-(1-hydroxy-1,3-dihydro-benzo[c][1,2]oxaborol-5-yloxy)-benzoic acid ((C38), 0.5 g, 1.75 mmol) in DMF (20 mL) were added N,N-dimethylamino ethanol (0.37 mL, 3.7 mmol) and EDCI (0.71 g, 3.7 mmol). The reaction was stirred at room temperature overnight. Then DMF was evaporated under vacuum. The residue was purified over silica gel, eluting with 5% MeOH/DCM, to afford the 0.35 g of the title compound in 56% yield. 1H NMR 400 MHz (DMSO-d6) δ: 7.97 (d, J=8.9 Hz, 2H), 7.76 (d, J=7.8 Hz, 1H), 7.15-7.07 (m, 4H), 4.95 (s, 2H), 4.33 (t, J=5.5 Hz, 2H), 2.58 (t, J=5.9 Hz, 2H), 2.20 (s, 6H); MS (ES) m/z: 342 (M+H)+; HPLC purity: 91.90% (220 nm), 94.99% (254 nm).
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