Reaction Steps
To a solution of 6-((trans)-4-aminocyclohexylamino)-N-(3-fluoropyridin-4-yl)-8-(pyridin-2-ylamino)imidazo[1,2-b]pyridazine-3-carboxamide (0.020 g, 0.043 mmol) in DMF (1 mL) at room temperature was added DIEA (0.038 mL, 0.217 mmol), (R)-2-(tert-butoxycarbonylamino)propanoic acid (0.016 g, 0.087 mmol), and BOP (0.058 g, 0.130 mmol). The resulting clear, colorless solution was stirred at room temperature for 30 minutes. Volatiles were removed in vacuo and the crude material was suspended in dichloromethane (0.5 mL) and TFA (0.5 mL). The resulting suspension was stirred vigorously at room temperature for 1.5 h. Volatiles were removed via a stream of nitrogen, and the crude material was diluted with 1 mL MeOH and purified via preparatory HPLC using a YMC ODS C-18 column (30×250 mm) 0%-100% B. Solvent B: (90% MeOH, 10% H2O, 0.1% TFA). Solvent A: (10% MeOH, 90% H2O, 0.1% TFA). Gradient, start % B=0, final % B=100, gradient time 60 min, flow rate 25 mL/min. Rt=49.547 min. 6-((trans-4-(D-alanylamino)cyclohexyl)amino)-N-(3-fluoro-4-pyridinyl)-8-(2-pyridinylamino)imidazo[1,2-b]pyridazine-3-carboxamide (0.006 g, 18.20% yield) was obtained as a white solid. LC/MS, m/z 533.2 (M+1). HPLC Rt=3.616 min. YMC S5 ODS-A column (4.6×50 mm) 0%-100% B. Solvent B: (90% MeOH, 10% H2O, 0.2% H3PO4). Solvent A: (10% MeOH, 90% H2O, 0.2% H3PO4). Gradient, start % B=0, final % B=100, gradient time 4 min, hold at 100% 1 min, flow rate 4 mL/min. 1H NMR (400 MHz, DMSO-d6) δ ppm 11.27 (1H, d, J=1.76 Hz), 9.85 (1H, s), 8.67 (1H, d, J=2.77 Hz), 8.48-8.55 (1H, m), 8.44 (1H, d, J=5.54 Hz), 8.34 (1H, dd, J=4.91, 1.38 Hz), 8.28 (1H, d, J=7.55 Hz), 8.13 (1H, s), 8.04 (2H, d, J=4.53 Hz), 7.98 (1H, s), 7.71-7.78 (1H, m), 7.51 (1H, d, J=8.31 Hz), 7.28 (1H, d, J=8.31 Hz), 7.02 (1H, dd, J=7.05, 5.79 Hz), 3.87 (1H, s), 3.73-3.81 (1H, m), 3.58 (1H, s), 2.07 (2H, d, J=3.78 Hz), 1.86 (2H, s), 1.34 (3H, d, J=6.80 Hz), 1.28-1.44 (4H, m).
