To a solution of 3-(β-D-glucopyranosyloxy)-4-[(4-isopropoxyphenyl)methyl]-1-isopropyl-5-methylpyrazole (0.10 g) in 2,4,6-trimethylpyridine (1 mL) was added propionyl chloride (0.072 g) at 0° C., and the mixture was stirred for 5 hours. To the reaction mixture were added citric acid monohydrate (3.3 g) and water, and the resulting mixture was purified by ODS solid phase extraction (washing solvent: distilled water, eluent: methanol). Further purification by column chromatography on silica gel (eluent: dichloromethane/methanol=10/1) afforded 4-[(4-isopropoxyphenyl)methyl]-1-isopropyl-5-methyl-3-(6-O-propionyl-β-D-glucopyranosyloxy)pyrazole (0.074 g)
