Chemical synthesis of parasitic glycoconjugates and phosphoglycans

The glycosylphosphatidylinositols (GPIs) are a class of natural glycosylphospholipids that anchor proteins, glycoproteins, and lipophosphoglycans (LPGs) to the membrane of eukaryotic cells. This chapter reviews the progress and recent achievements in the chemical synthesis of the glycoconjugate structures like glycosylphosphatidylinositol anchors and phosphoglycans of the protozoan parasites Trypanosoma brucei, Trypanosoma cruzi, Toxoplasma gondii, Plasmodium falciparum, and Leishmania. Synthetic strategies toward GPI anchors and GPI-related glycoconjugates have matured since the first synthesis published in the early 1990s. Several attractive synthetic routes used for the preparation of the parasitic structures discussed in this chapter. In addition, synthesis of a GPI anchor found in the yeast Saccharomyces cerevisiae and a few structures from the higher eukaryotes have been discussed. A common feature in most of the strategies used (with the exception of CD52 GPIs) is the initial construction of the GPI glycan core having the appropriate orthogonal protecting groups, followed by subsequent introduction of the phosphate moieties. Almost all strategies use benzyl ethers as permanent O-protecting groups.