3.24 g of ethyl 5-{(2RS,3RS)-3-azido-2-(4-nitrophenyl)butyl}-2-furancarboxylate was dissolved in a mixed solution of 50 ml of tetrahydrofuran and 5 ml of water, and 2.37 g of triphenylphosphine was added thereto, followed by heating and refluxing for 6 hours. The reaction solution was left to cool to room temperature, and then ethyl ether and water were added thereto for extraction. The organic layer was washed with a saturated sodium chloride aqueous solution and then dried over anhydrous magnesium sulfate. The drying agent was filtered off, and then, the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (methylene chloride/methanol=100/1+20/1) to obtain 2.89 g of the above-identified compound.
