Synthesis of polar head group homologs of all-trans-cyclopentano-phosphatidylcholine, phosphatidyl-N,N-dimethylethanolamine, and phosphatidylethanolamine.

The polar head group region of a conformationally restricted analog of phosphatidic acid (diacylglycero-phosphate) has been systematically modified to give analogs of phosphatidylcholine, phosphatidylethanolamine, and phosphatidyl-N,N-dimethylethanolamine. These analogs differ from their natural counterpart in both the backbone region and in the polar head region, respectively, as follows: the diacylglyceryl moiety has been replaced by an all-trans diacylcyclopentane-1,2,3-triol moiety and the phosphorus-nitrogen separation has been increased incrementally from two to nine methylene units. The synthesis of these homologous series involved phosphorylation of (1,3/2)-2,3-dipalmitoylcyclopentane-1,2,3-triol with each of a series of homologous bromoalkylphosphoric acid dichlorides, which were themselves obtained by phosphorus oxychloride treatment of the homologous bromoalkanols. The resulting bromoalkyl esters of 2,3-dipalmitoylcyclopentane-1,2,3-triol-1-phosphoric acid were reacted with trimethylamine, dimethylamine, or ammonia to give the cyclopentano-phosphatidylcholines, cyclopentano-N,N-dimethylethanolamines, and cyclopentano-phosphatidylethanolamine, respectively. All the compounds were obtained as stable microcrystalline solids. The yields of cyclopentano-phosphatidylethanolamines and of cyclopentano-N,N-dimethylethanolamines were reduced by the formation of compounds which analyzed as monoacyl (lyso) derivatives.