Reaction Steps
A solution of N-(2,2-difluoroethyl)-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-7-methyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazin-2-amine TFA salt (15 mg, 0.027 mmol), acetic anhydride (5.1 μL, 0.054 mmol), and DIPEA (14.2 μL, 0.081 mmol) in DCM (136 nL) was stirred at room temperature overnight. The crude reaction mixture was diluted in DMF, filtered through a hydrophilic PTFE 0.45 nm filter (Millipore® Millex-LCR), and purified via HPLC Method A to give the title compound as a TFA salt (8 mg) as a clear oil. 1H NMR (400 MHz, methanol-d4, mixture of rotamers) δ ppm 1.13 (d, J=6.8 Hz, 1.4H), 1.23 (d, J=6.8 Hz, 1.6H), 1.92-2.03 (m, 2H), 2.09-2.17 (m, 2H), 2.18 (s, 1.4H), 2.22 (s, 1.6H), 2.54-2.67 (m, 1H), 2.95-3.04 (m, 2.4H), 3.13 (dd, J=16.7, 6.3 Hz, 0.6H), 3.34-3.44 (m, 2H), 3.74-3.83 (m, 2.4H), 3.99 (d, J=18.2 Hz, 0.6H), 4.40-4.49 (m, 1H), 4.55 (quin, J=6.6 Hz, 0.5H), 4.66 (d, J=16.7 Hz, 0.5H), 5.07 (d, J=17.7 Hz, 0.5H), 5.18 (m, 0.5H), 5.90-6.22 (m, 1H), 6.84-6.91 (m, 1H), 6.98 (ddd, J=11.2, 8.5, 3.0 Hz, 1H), 7.18 (td, J=9.2, 5.3 Hz, 1H); ESI-MS m/z [M+H]+ 481.9.
