Trifluoroacetic acid → 1-(4-(1-(2-methoxyethyl)-8-phenyl-4H-pyrido[2,3-b][1,2,4]triazolo[4,3-d][1,4]oxazin-7-yl)phenyl)cyclobutanamine

Tert-butyl (1-(4-(1-(2-methoxyethyl)-8-phenyl-4H-pyrido[2,3-b][1,2,4]triazolo[4,3-d][1,4]oxazin-7-yl)phenyl)cyclobutyl)carbamate (12 mg, 0.022 mmol) was dissolved in dichloromethane (0.5 ml); TFA (0.5 ml) was added at room temperature and the resulting mixture was stirred for 30 seconds. The solution was immediately concentrated to dryness under reduced pressure. The residue was dissolved in diethyl ether (˜2 ml) and concentrated to dryness under reduced pressure. This was repeated three times. The residue was then slurred in diethyl ether (2 ml) and after settling the supernatant solvent was removed by pipette. This was repeated three times. The residue was then slurred in n-hexane (2 ml) and after settling the supernatant solvent was removed by pipette. This was repeated three times. The remaining solvent was removed under reduced pressure and dried to give the desired product as an off-white solid (5 mg, 50% yield). LCMS (Method D) RT=0.741 min, M+1=454. 1H-NMR (500 MHz, CD3OD) δ 8.40 (1H, s), 7.52-7.47 (2H, d), 7.46-7.41 (2H, d), 7.38-7.34 (3H, m), 7.32-7.26 (2H, dd), 5.65 (2H, s), 3.94 (2H, t), 3.49 (2H, t), 3.35 (3H, s), 2.82-2.74 (2H, m), 2.63-2.54 (2H, m), 2.30-2.19 (1H, m), 2.04-1.93 (1H, m).