To a mixture of methylmagnesium bromide (1 M THF solution, 6.81 mL) in THF (6 mL) was added a mixture of ethyl (8R)-3-[3-methoxy-4-(2-methyl-1,3-oxazol-5-yl)phenyl]-8-(3,4,5-trifluorophenoxy)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyridine-8-carboxylate (1 g) in THF (6 mL) at 0° C., and the mixture was stirred at room temperature for 3 hr. The reaction mixture was diluted with ethyl acetate and saturated aqueous ammonium chloride solution, the mixture was washed with saturated brine and dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (NH, ethyl acetate) to give the title compound (0.63 g) as a solid.
