Treatment of the N-aryl oxalamic acid ethyl ester (I) with butylamine in toluene provides the oxalic diamide (II). The nitro group of (II) is then reduced to the corresponding amine (III) by catalytic hydrogenation over Pd/C. Subsequent thermal cyclization of the N-acyl phenylenediamine (III) leads to benzimidazole (IV). Hydrolysis of both the methyl ether and amide functions of (IV) with concentrated HBr furnishes 6-hydroxy-1H-benzimidazole-2-carboxylic acid (V). Then, coupling of acid (V) with 4-benzylpiperidine (VI) in the presence of TBTU gives rise to the desired amide