As shown in step 3-iv of Scheme 3, to a solution of tert-butyl (-4-((7-morpholinoquinoxalin-5-yl)amino)cyclohexyl)carbamate (900 mg, 2.00 mmol) in dichloromethane (16 mL) was added trifluoroacetic acid (3 mL, 38.9 mmol). The resulting black reaction mixture was stirred under an atmosphere of nitrogen at room temperature for 2 hours. Saturated aqueous sodium bicarbonate (150 mL) was added slowly until the color turned from black to orange. The mixture was extracted with dichloromethane (2×100 mL) and the combined organics washed with brine (50 mL), dried over sodium sulfate, and concentrated under reduced pressure to provide-N1-(7-morpholinoquinoxalin-5-yl)cyclohexane-1,4-diamine, trifluoroacetate (compound 1005): 1H NMR (300 MHz, CDCl3) δ 8.64 (d, J=1.9 Hz, 1H), 8.36 (d, J=1.9 Hz, 1H), 6.59 (d, J=2.3 Hz, 1H), 6.34 (d, J=2.3 Hz, 1H), 6.20 (d, J=7.9 Hz, 1H), 3.95-3.84 (m, 4H), 3.69 (s, 1H), 3.41-3.25 (m, 4H), 2.93 (d, J=8.9 Hz, 1H), 2.09-1.87 (m, 2H), 1.90-1.68 (m, 6H), 1.58 (dd, J=11.2, 8.7 Hz, 2H); ESMS (M+H+)=328.34. This compound was used as is without further purification.
