Into a tube was added 6-(trifluoromethyl)picolinaldehyde (150 mg, 0.47 mmol), (R)-(1-(6-amino-5-nitropyridin-2-yl)piperidin-3-yl)(pyrrolidin-1-yl)methanone (Intermediate 1, Step 3) (82.2 mg, 0.47 mmol), sodium dithionite (310.7 mg, 1.78 mmol), ethanol (10 mL) and water (1.5 mL). The vessel was sealed and the reaction mixture was stirred at 110° C. for 16 h. The solvent was evaporated under reduced pressure and water was added to the resulting residue. The mixture was extracted with ethyl acetate, dried over sodium sulfate and concentrated under reduced pressure. The crude material was purified via preparative TLC to afford the title compound (50 mg, 29%) as a yellow solid. MS (ES+APCI) (M+H) 445.2; LCMS retention time 2.657 min (Method G).
