Monomeric sugars, such as glucose, galactose and mannose, are abundant, renewable and inexpensive. They are also biocompatible and therefore are especially useful as starting materials to synthesize polymers for biological and biomedical applications. Numerous efforts have been invested in the syntheses of sugar-containing polymers. Most of these efforts are focused on living radical polymerizations (LRP), wherein the sugar units are chemically attached to vinyl functionalities to form monomers, which are then subjected to radical polymerizations to give glycopolymers that have non-degradable backbones.For biomedical applications, it is highly desired to synthesize degradable, sugar-containing polymers. However, this practice has proved challenging. Today, most degradable sugar-containing polymers are synthesized by either cationic ring-opening polymerization (ROP) or chemical glycosylation, each of which poses its own set of disadvantages.Herein, we report two efficient approaches to synthesize polysaccharides using glucose as the starting material. In approach A , 2,3,4-tri-O-acetyl-alpha-D-glucosyl bromide was synthesized as a di-functional AB monomer. The synthesis of the monomer was achieved through a series of chemical manipulations of glucose. The monomer was then subjected to polycondensation using silver carbonate as a promoter. Under microwave irradiation, 1,6-beta-glycosylated polysaccharides were synthesized with molecular weights of 4.1 kDa. In approach B , when tetrabutyl ammonium iodide (TBAI) was used as a promoter, sugar poly(orthoesters) were synthesized with molecular weights up to 6.9 kDa. In this case, all sugar units were connected by orthoester linkages. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/240nm/uploads/45744__figure1_.jpg' alt='' />

Syntheses of polysaccharides from simple sugars

247th National Meeting (2014)

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