A mixture of 4′-({4-[trans-4-(oxiran-2-ylmethoxy)cyclohexyl]-5-oxo-7-propyl-4,5-dihydro[1,2,4]triazolo[1,5-a]pyrimidin-6-yl}methyl)biphenyl-2-carbonitrile (0.25 g), potassium hydrogen fluoride (0.075 g), tetra-n-butylammonium dihydrogentrifluoride (0.015 g) and chlorobenzene (1 mL) was stirred at 120° C. for 5 hr. Potassium hydrogen fluoride (0.075 g) and tetra-n-butylammonium dihydrogentrifluoride (0.014 g) were added, and the mixture was stirred at 120° C. for 16 hr. Toluene was added, and the precipitate was filtered off. The filtrate was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography to give the title compound as a colorless solid (0.15 g, 60%).
