550 Milligrams of 1-[2,5-dimethoxy-3,6-bis(methoxymethoxy)phenyl]-5-[2,5-dimethoxy-3,6-bis(methoxymethoxy)-4-(2-methoxymethyloxyethyl)phenyl]pentane was dissolved in a mixed solvent of 8 ml of toluene with 2 ml of hexamethylphosphoric triamide, to this solution was added 0.12 ml of N,N,N',N'-tetramethylethylenediamine and the whole mixture was cooled to -78° C. in a dry ice-acetone bath, then 0.64 ml of n-butyllithium was added to the reaction mixture. 15 Minutes later, 0.16 ml of n-butyl iodide was added to the reaction mixture, and temperature of the reaction mixture was gradually elevated to room temperature, and further stirred for 4 hours. 50 Milliliters of diethyl ether was added to the reaction mixture, and the organic layer was washed with water, a saturated sodium chloride aqueous solution, dried over anhydrous magnesium sulfate, and then concentrated. The residue obtained was purified by means of a silica gel column chromatography (diameter 2 cm×length 10 cm, adsorbent: "Silica gel 60" manufactured by E. Merck A. G., developing solvent: 30% ethyl acetate-hexane) to obtain 520 mg of 1-[2,5-dimethoxy-4-butyl-3,6-bis(methoxymethoxy)phenyl]-5-[2,5-dimethoxy-3,6-bis(methoxymethoxy)4-(2-methoxymethyloxyethyl)phenyl]pentane. Amorphous powdery substance.
