A mixture of 0.15 g (0.25 mmol) of 3-[[6-(2,3-dihydroxyphenyl) hexyl]oxy]-5-(octadecyloxy)benzoic acid, 0.05 g (0.6 mmol) of sodium bicarbonate and 0.64 ml (10 mmol) of methyl iodide in 3 ml of DMF was stirred and heated at 40° for 5 days. An additional 0.32 ml of methyl iodide and 0.05 g of sodium bicarbonate were added and heating at 40° was continued for 6 days. The solvent was removed at reduced pressure, the residue was extracted with ethyl acetate and the extract was washed with water. The dried extract was concentrated to an oil which was purified by chromatography on 4 g of silica gel using 25% ethyl acetate-hexane to give 0.104 g (68% yield, mp 82°-84°) of 3-[[6-(2,3-dihydroxyphenyl)hexyl]oxy]-5-(octadecyloxy)benzoic acid methyl ester.
