A solution of tert-butyl {(3S)-1-[3-({[6-(2,6-difluorophenyl)-5-fluoropyridin-2-yl]carbonyl}amino)-6,7-dihydro-5H-cyclopenta[b]pyridin-4-yl]piperidin-3-yl}carbamate (4.0 mg, 0.0070 mmol) in DCM (0.02 mL) was treated with TFA (0.03 mL, 0.4 mmol). The resulting reaction mixture was stirred at room temperature for 30 min. and then concentrated to give a residue, which was diluted with MeOH and neutralized with small amount of NH4OH. After filtration, the crude was purified by preparative LC-MS (XBridge™ preparative C18 5 μm 30×10 mm OBD™ column, flow rate 60 mL/min., eluting with a gradient of MeCN and water with 0.15% NH4OH) to afford the title compound (2.2 mg, 67%). LCMS calc. for C25H25F3N5O (M+H)+: m/z=468.2. Found: 468.1.
