4-Methyl-2-propyl-1H-benzimidazole (464 mg) was dissolved in a mixture of 50 ml of DMF and 80 ml of toluene, and 106.4 mg of sodium hydride (60% oily) was added to the solution under ice cooling, followed by stirring for 30 minutes. To the mixture was added 732 mg of Compound 1-c, and the mixture was heated under reflux for 3 hours. After the solvent was distilled off under reduced pressure, the residue was diluted with ethyl acetate. The organic layer was washed with a saturated aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography [eluent: hexane/ethyl acetate/triethylamine (20/5/1)] to give 629 mg (61%) of the product.
