To a suspension of 997 mg (3.67 mM) of o-nitrophenylselenium cyanide in 12 ml of anhydrous tetrahydrofuran was dropwise added 886 mg (1.83 mM) of (3R,4S,7S) 3,7-dibenzyloxy-4-(2'-hydroxyethyl)-1,1-dimethoxydodeca-5-ene [7] described above. The mixture was stirred for several minutes and 0.91 ml (3.67 mM) of tri-n-butylphosphine was dropwise added to the mixture. The reaction solution was stirred for ten minutes then cooled to 0° C. and 35% hydrogen peroxide aqueous solution was dropwise added thereto at the same temperature while stirring. After stirring for 3 hours, the aqueous phase was extracted with a solvent mixture of diethyl ether:hexane=7:3. The extracts were combined and washed sequentially with saturated sodium bicarbonate aqueous solution and saturated sodium chloride aqueous solution. After drying over anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure. The precipitated crystals were taken from the residue by filtration to give 776 mg (1.67 mM) of (3R,4 S,7S) 3,7-dibenzyloxy-4-vinyl-1,1-dimethoxydodeca-5-ene [8]. Yield, 91%.
