Diallyl 2-(hydroxymethyl)-6-methoxybenzyl phosphate (715.0 mg, 2.18 mmol) obtained from Example 21-(4) was dissolved in N,N-dimethylformamide (8 ml), and pyridinium dichromate (2.87 g, 7.63 mmol) was added thereto. After the mixture was stirred at room temperature for 12 hours, water (60 ml) was added thereto, and the product was extracted with diethyl ether. The organic layer was washed successively with water, a 2N aqueous solution of hydrochloric acid, and a saturated aqueous solution of sodium chloride, and then the solvent was distilled off under reduced pressure to give an oily residue. The residue was dissolved in acetone (5 ml), and Jones reagent (a mixture of chromic anhydride (5.34 g, 4 mmol) and concentrated sulfuric acid (4.6 ml) diluted with water to 20 ml total volume; 1.5 ml) was added thereto. The reaction mixture was stirred at room temperature for 1.5 hours, and then 2-propanol (1 ml) was added thereto to stop the reaction. The solid insoluble material was filtered off, and the filtrate was concentrated under reduced pressure to give an oily residue. The residue was dried using a vaccum pump, and then subjected to chromatography on a silica gel (25 g) column (eluent; ethyl acetate:dichloromethane=1:1) to afford the title compound (447.0 mg, 60% yield) as a colorless oil.
