A solution of 501 mg of 7,7-ethylenedioxy-3-oxo-cis-bicyclo[3,3,0]octane in 5 ml of diethyl ether was added dropwise at room temperature to 5-benzyloxypentamethylene-magnesium bromide, which had been prepared in 5 ml of diethyl ether from 1.00 g of 5-benzyloxypentyl bromide and 100 mg of metallic magnesium at room temperature. The 5-benzyloxypentyl bromide, in turn, had been prepared from pentamethylene bromide and benzyl alcohol according to the method of A. W. Burgstabler et al. [J. Org. Chem. 42, 566 (1977)]. The mixture was stirred for 1.5 hours at room temperature. Upon completion of the reaction, an aqueous solution of ammonium chloride was added to the reaction mixture, which was then extracted with diethyl ether. The extract was washed with water and dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure, giving 1.47 of residue. On purifying the residues by silica gel column chromatography, 556 mg of the title compound were obtained as an oil from the fractions eluted with hexane containing 25-30% by volume of ethyl acetate.
