2,3-Bis-((3R,5S)-3,5-bis-(tert-Butoxycarbonylamino)-piperidin-1-yl)-6-nitro-quinoxaline (3) (0.159 g, 0.198 mmol) was dissolved in a mixture of EtOAc (3 mL) and MeOH (3 mL). The solution was heated to 60° C. and Raney Nickel (0.25 mL, 50% slurry in water) and hydrazine (0.5 mL, anhydrous) were added. Bubbling was observed. The mixture continued to stir for 15 minutes at 60° C. TLC (Rf: 0.05 compared to Rf: 0.3 for compound 245 in 1:1 hexanes/EtOAc) indicated complete reduction at this point. The mixture was passed through a plug of silica gel and concentrated to give a white powder. The solid was dissolved in EtOAc (30 mL), washed with water (2×20 mL) and brine (2×20 mL) via extraction, dried over MgSO4 and concentrated to give the desired product (246) as a white powder (0.135 g, 0.175 mmol, 88.3% yield). LC-MS (ESI): (exact mass: 771.46) m/e=772.6 [M+1]+.
