1-(N,N-dimethylcarbamoyl)piperidine-4-carboxylic acid (300 mg, 1.50 mmol) obtained in Step 2 was dissolved in dichloromethane (15 mL), and thionyl chloride (0.547 mL, 7.50 mmol) was added thereto, followed by stirring under heating and reflux for 1 hour. The reaction mixture was concentrated under reduced pressure, and the resulting residue was dissolved in chloroform (5 mL). The resulting solution was added to a pyridine (10 mL) solution of 2-amino-4-(2-furyl)-5-morpholinothiazole (126 mg, 0.50 mmol) obtained in Step 1 of Example 29, followed by stirring at room temperature for 1 hour. The reaction mixture was concentrated under reduced pressure, and the resulting residue was purified through silica gel column chromatography (ethyl acetate:methanol=9:1) to afford the entitled Compound 55 (171 mg, 81%).
