Synthesis and characterization of rac‐1,2‐bis(palmitoyloxy)‐3‐propyl (2‐trimethylarsonioethyl)phosphonate, an arsenic‐containing phosphonolipid

Arsenic analogs of lecithins (i.e. with replacement of nitrogen by arsenic in the choline group) are probably trace constituents of phospholipids in many organisms. Attempts to synthesize 1,2‐bis(palmitoyloxy)‐3‐propyl 2‐trimethylarsonioethyl phosphate (arsenolecithin) according to wellestablished procedures for the synthesis of the corresponding nitrogen compound failed. However, 1,2‐bis(palmitoyloxy)‐3‐propyl 2‐trimethylarsonioethylphosphonate, an arsenic‐containing phosphonolipid, was obtained in 16% yield by reacting 1,2‐bis(palmitoyloxy)‐3‐iodopropane with silver 2‐trimethylarsonioethylphosphonate in isopropanol. The precursors to the arsenic‐containing phosphonolipid were obtained by quaternization of trimethylarsine with diethyl 2‐bromoethylphosphonate, hydrolysis of the resulting product with concentrated hydrochloric acid, and reaction of the phosphonic acid with silver oxide to give silver 2‐trimethylarsonioethylphosphonate. Quaternization and hydrolysis proceeded almost quantitatively. The silver phosphonate was not isolated but was used in situ .