Biosynthesis of oligo- and polysaccharide

Sect. 2 below summarizes some of the important structures containing pyruvic acid acetals. The structural diversity, methods for structure elucidation, biosynthesis and biological function of these oligo- and polysaccharides will be briefly discussed. Sect. 3 gives an overview of the synthetic methods for the stereoselective preparation of pyruvated building blocks for oligosaccharide synthesis. Here, special attention is paid to pyruvated glycosyl donors, and their application to the synthesis of selected structures is presented in Sect. 4. 

The biosynthetic pathway of pyruvated oligo- and polysaccharides is not clear yet. However, it has been demonstrated for rhizobial polysaccharides that pyruvic acetal formation occurs at a late stage of the biosynthesis of the sugar chain. Furthermore, the pyruvic acid acetal is most probably introduced by an initial transfer of a propenoate-2-yl residue from phosphoenolpyruvate to a glycosyl residue followed by spontaneous ring closure [26]. 

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