Arachidonic acid (152 mg, 0.5 mmol) and triethylamine (52 mg, 0.51 mmol) were dissolved in 3 ml of dry acetonitrile and chilled to −15° C., and 70 mg (0.51 mmol) of butyl chloroformate was added. After 30 min, the mixture free of the precipitated triethylamine hydrochloride was pipetted in a solution of cystamine dihydrochloride (56 mg, 0.25 mmol) and triethylamine (52 mg, 0.51 mmol) in 1 ml of methanol, stirring was continued for 15 min at −15° C., then the mixture obtained was allowed to warm to room temperature. After 2 h, 0.5 M HCl was added, and the mixture was extracted with ether (20 ml). The extract was washed with water, then dried with Na2SO4, and evaporated under reduced pressure. The residue was dissolved in 2 ml of chloroform and purified by column (2×2 cm) chromatography on aluminium oxide (basic, Brockmann II). Elution of the column with chloroform-methanol (9:1 v/v) and evaporation of the appropriate fractions gave 181 mg (75%) of the desired N,N′-diarachidonoylcystamine as a waxy solid: TLC, Merck silica gel 60 pre-coated plates [system A: benzen-dioxan-acetic acid (25:5:1 v/v/v)] Rf0.5.
