tert-Butyl 9-methyl-2-(2-oxo-4-((6-(trifluoromethyl)pyridin-3-yl)methoxy)pyridin-1(2H)-yl)-5,7,8,9-tetrahydro-6H-pyrido[3′,4′:4,5]pyrrolo[2,3-b]pyridine-6-carboxylate (0.43 g, 0.77 mmol) was treated with 1.25 M HCl in MeOH (15 mL), and the resulting solution was stirred at ambient temperature for 18 h. The solution was diluted with Et2O (50 mL). The resulting solids were collected by filtration, dissolved in 10:3 CH2Cl2/MeOH (50 mL), and washed with saturated NaHCO3 solution (50 mL). The aqueous layer was extracted with CH2Cl2 (8×25 mL), and the organic extracts were combined. The remaining solids in the aqueous solution were separated by filtration and washed with MeOH (100 mL). The resulting filtrate was extracted with CH2Cl2 (3×50 mL). All the organic extracts were combined and concentrated to dryness under reduced pressure. The resulting residue was diluted in CH2Cl2, washed with brine (2×20 mL), dried over Na2SO4, filtered, and concentrated to dryness under reduced pressure to provide the title compound (0.27 g, 76%) as an off-white powder: 1H NMR (500 MHz, DMSO-d6) δ 8.89 (d, J=1.5 Hz, 1H), 8.19 (dd, J=8.0, 1.5 Hz, 1H), 7.99 (d, J=8.0 Hz, 1H), 7.88 (d, J=8.0 Hz, 1H), 7.83 (d, J=8.0 Hz, 1H), 7.24 (d, J=8.0 Hz, 1H), 6.19 (dd, J=7.5, 2.5 Hz, 1H), 6.03 (s, J=3.0 Hz, 1H), 5.36 (s, 2H), 3.87 (s, 2H), 3.65 (s, 3H), 3.08 (t, J=5.5 Hz, 2H), 2.74 (t, J=5.5 Hz, 2H).
