To a solution of N-hydroxysuccinimide ester of 3-hexadecanoyloxyoctadecanoic acid (1.5 g) in tetrahydrofuran (100 ml) were added a solution of N-(L-threonyl)-L-glutamic acid (0.79 g) and triethylamine (0.88 ml) in water (220 ml). The resulting mixture was stirred at ambient temperature overnight. The reaction mixture was acidified with 1N hydrochloric acid, extracted with ethyl acetate, washed with water and dried over magnesium sulfate. Ethyl acetate was distilled off to give a residue which was purified by silica gel column chromatography. Elution with chloroform-methanol (20:1) afforded powder of N-[N-(3-hexadecanoyloxyoctadecanoyl)-L-threonyl]-L-glutamic acid (1.0 g).
