To a solution of 1-(3-methoxy-4-((6-methoxypyridin-3-yl)methoxy)benzyl)-1H-benzo[d]imidazole-5-carboxylic acid (0.30 g, 0.72 mmol) in dichloromethane was added tert-butyl 4-(hydrazinocarbonyl)piperidine-1-carboxylate (0.24 g, 0.98 mmol), 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxid hexafluorophosphate (0.34 g, 0.89 mmol), diisopropylamine (0.19 g, 1.47 mmol). The resulting mixture was allowed to stir at room temperature. After 16 h, the mixture was concentrated and the residue was purified by silica gel chromatography (2% methanol/dichloromethane elute) to afford 0.30 g (65%) tert-butyl 4-(2-(1-(3-methoxy-4-((6-methoxypyridin-3-yl)methoxy)benzyl)-1H-benzo[d]imidazole-5-carbonyl)hydrazinecarbonyl)piperidine-1-carboxylate as a yellow solid.
