Classical Tools for Oligosaccharide Synthesis

Abstract

The chemical synthesis of complex carbohydrates has been a challenging and difficult task for more than a century [1]. The big difference with the other two major classes of biopolymers, oligonucleotides and proteins, is that several points for further attachment (hydroxyls and amines) are commonly available at one monosaccharidic building block. Thus, even with two subunits, a variety of different dimers can be obtained. With more than two subunits, branched structures might arise as well. The situation becomes even more difficult, since a glycosidic linkage between two subunits creates a new stereogenic center. A recent statistical analysis regarding the diversity of mammalian carbohydrate structures, based on the "10 mammalian monosaccharides" without considering any further attachments, reveals astonishing numbers that dwarf the complexity of both peptides and oligonucleotides by orders of magnitude [2]. Although the number of structural combinations encountered in nature is much smaller than the theoretical ones, it is evident that glycochemists have to face a variety of challenges during the preparation of an oligosaccharide by chemical means. Carbohydrate Chemistry: State of the Art and Challenges for Drug Development Downloaded from www.worldscientific.com by UNIVERSITY OF PITTSBURGH on 10/02/15. For personal use only.