To a mixture of 4′-{[4-(3-methylidene-1,5-dioxaspiro[5.5]undec-9-yl)-5-oxo-7-propyl-4,5-dihydro[1,2,4]triazolo[1,5-a]pyrimidin-6-yl]methyl}biphenyl-2-carbonitrile (2.0 g), sodium periodate (4.1 g), acetone (40 mL), acetonitrile (40 mL) and water (40 mL) was added osmium tetraoxide (1.48 g, 7% immobilized catalyst) at 0° C., and the mixture was stirred at room temperature for 8 hr. Sodium periodate (1.6 g) and osmium tetraoxide (0.60 g, 7% immobilized catalyst) were added, and the mixture was further stirred at room temperature for 16 hr. Ethyl acetate and water were added to the reaction mixture, the precipitate was filtered off, and the filtrate was extracted with ethyl acetate. The organic layer was washed with saturated brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure, and the residue was dissolved in tetrahydrofuran (10 mL) and methanol (20 mL), sodium tetrahydroborate (0.29 g) was added, and the mixture was stirred at room temperature for 2 hr. Saturated aqueous sodium hydrogen carbonate solution was added to the reaction mixture. After evaporation of the solvent under reduced pressure, the residue was extracted with ethyl acetate. The organic layer was washed with saturated brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography to give the title compound as a colorless solid (1.5 g, 73%).
