5-Methylimidazole-4-carboxylic acid hydrochloride (G. Wellman et al., Synthesis, 356 (1984); 1.6 g) was suspended in acetonitrile (100 ml). HOBt (2.8 g) and WSC (3.5 g) were sequentially added thereto, and mixed at room temperature for 20 minutes (the reaction solution A). In a separate flask were dissolved tert-butyl 4-(2-hydroxyethyl)amino-1-piperidinecarboxylate (3.0 g) obtained in Example 91a), N-trimethylsilylacetamide (8.1 g) and triethylamine (5.0 ml) in acetonitrile (50 ml), and mixed at room temperature for 20 minutes (the reaction solution B). The reaction solution B was added to the reaction solution A, and mixed at room temperature for 15 hours. Acetonitrile was distilled off under reduced pressure, and then to the residue were added chloroform and water. The organic layer was collected by separation and dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was purified with basic silica gel column (ethyl acetate:ethanol=5:1) to obtain the title compound as a colorless oil (2.0 g, 59%).
