Under a nitrogen atmosphere, to a mixture of 5.55 g of (2R)-1-{[tert-butyl(dimethyl)silyl]oxy}-2-[2-(difluoromethyl)-2H-tetrazol-5-yl]propan-2-amine, 7.5 ml of triethylamine, 220 mg of 4-dimethylaminopyridine, and 110 ml of 1,2-dichloroethane was added 8.88 g of 8-[(2,6-difluorobenzyl)oxy]-2-methylimidazo[1,2-a]pyridine-3-carbonyl chloride hydrochloride, followed by stirring at 70° C. for 2 hours. The reaction mixture was left to be cooled to room temperature, and was added to the mixture of water and ethyl acetate. The insoluble materials were separated by filtration and washed with ethyl acetate, and the aqueous layer was extracted with ethyl acetate. The organic layer was combined, washed with water and a saturated aqueous sodium chloride solution, and dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography to obtain 8.70 g of N-{(2R)-1-{[tert-butyl (dimethyl)silyl]oxy}-2-[2-(difluoromethyl)-2H-tetrazol-5-yl]propan-2-yl}-8-[(2,6-difluorobenzyl)oxy]-2-methylimidazo[1,2-a]pyridine-3-carboxamide.
