185961-99-3

1146637-16-2

185961-99-3

Step 4: 690 g (1.96 mol) of benzyl 4-(2-oxo-2,3-dihydroimidazo[4,5-b]pyridin-1-yl)piperidine-1-carboxylate was dissolved in 5.4 L of methanol, heated to 60 °C and 46 g of 10% Pd/C catalyst was added (catalyst-to-substrate mass ratio of 6.6%). The hydrogenation reaction was carried out under 60 psi hydrogen pressure until hydrogen absorption was complete. Upon completion of the reaction, the catalyst was removed by filtration. 4 L of methanol was removed by distillation from the filtrate, followed by the addition of 2 L of methylcyclohexane and continued distillation to remove 1.5 L of solvent. The resulting suspension was diafiltrated and the residue was washed with methylcyclohexane and dried at 40 °C. Yield: 446 g (100%). eSI-MS: m/z = 219 (M + H)+.