(6-(5-Methoxy-1-methyl-1H-indol-3-yl)-5-((2-(trimethylsilyl)ethoxy)methyl)-5H-pyrrolo[2,3-b]pyrazin-2-yl)methanamine (0.185 g, 0.423 mmol) in THF (5 mL) was treated with pyridine (0.044 mL, 0.55 mmol) and acetic anhydride (0.044 mL, 0.47 mmol). The mixture was stirred for about 5 min at ambient temperature and treated with AcOH (0.024 mL, 0.42 mmol). The mixture was diluted with EtOAc (20 mL) and washed with water (15 mL) and brine (10 mL). The organic solution was dried over anhydrous MgSO4, filtered, and concentrated to give N-((6-(5-methoxy-1-methyl-1H-indol-3-yl)-5-((2-(trimethylsilyl)ethoxy)methyl)-5H-pyrrolo[2,3-b]pyrazin-2-yl)methyl)acetamide (0.202 g, 100%): LC/MS (Table 2, Method a) Rt=2.63 min; MS m/z: 480 (M+H)+.
