Vinyl sugars

G. Wulff, J. Schmid, and T. Venhoff, The synthesis of polymerizable vinyl sugars, Macromol. Chem. Phys., 197 (1996) 259-274. 

Zr-mediated ring-contraction reactions using vinyl sugars are useful to s)mthesize carbocy-cles [107,108]. This method was later employed successfully for aza-sugar s)mthesis. The... 

A variety of vinyl sugar monomers have been prepared and polymerized.154 Many of the syntheses involve various protecting groups. Probably, the most practical and direct syntheses are those involving enzymatic formation of acrylates (as described in Chapter 9). This has been used to produce sucrose acrylate, as well as a monomer (12.29) made from a-methylgalactose and vinyl acrylate. 

An entirely different approach to sugar-based polymers involves the use of selective enzymatic catalysts to prepare vinyl sugar monomers that are subsequently polymerized via chemical catalysts. Tokiwa and Kitagawa (25) published extensively on this subject, and their contribution within this book describes a wide range of sugar monomer structures. 

Sugar Based Polymers Overviews and Recent Advances of Vinyl Sugars... 

Sugar based polymers, which are obtained by polymerization of vinyl sugars, have recently received increased attention from two viewpoints. One is the development of environmentally friendly material from renewable resources. Another is physiologically active material that mimics carbohydrate on cell surface. This article provides an overview of known sugar based polymers and the recent advances of the poly(vinylalcohol) (PVA) with sugar pendants. 

The vinyl sugars having vinylether group are shown in Figure 6. Whistler et al. prepared 6-0-vinyl-l,2 3,4-di-0-isopropylidene D-galactopyranose 26 by bubbling acetylene with diisopropylidene galactose 45). 

The vinyl sugars mentioned above were acrylate, acrylamide, styryl, vinylether and alkenyl sugars, and their polymer backbones after polymerization are not biodegradable. 

Table 1. Vinyl sugars synthesized using various sugars and divinyl dicarboxylate by enzymatic catalyst...

Regioselective introduction of a bromine atom to a double bond in the substimted vinyl sugar is achieved by bromination with pyridinium tribromide and debromination with DBU (1) [55] (Scheme 3.35). -configuration of the product is expected from a specific anfi-addition in the bromination of the -alkene followed by on E2 (anfi-ehmination)... 

Besides these fields of applications, Wulff and co-workers (307,308) investigated the potential ability of glycopolymers to modify surface properties. Thus, they copolymerized several isopropylidene-protected vinyl sugars with styrene, methyl methacrylate, and acrylonitrile. After eliminating the isopropylidene protecting groups from the copol5uner surfaces by acid hydrolysis, these surfaces were shown to become hydrophilic with improved dyeability and surface conductivity. 

The objective of the present work was to demonstrate efficient routes to sugar-based vinyl monomers based on enzyme selectivity, determine whether 6-O -acryl glucoside was polymerizable and to synthesize water-soluble acrylic acid-based copolymers that also contain vinyl-sugar repeat units. 

Zirconium-mediated ring contraction of vinyl sugars is also a useful method for the preparation of carbocycles [25]. 

An intramolecular version of this tandem reaction has been applied to the synthesis of indanones and indenones (Scheme 4-294). Accordingly, a sequence of pentacarbonyliron-catalyzed isomerization, aldolization, and dehydration can be exploited to transform vinyl sugars into substituted cyclopentenones (Scheme 4—295). The latter represent versatile intermediates for the synthesis of a variety of natural products. ... 

Scheme 4-295. Pentacarbonyliron-catalyzed isomerization, aldolization, and dehydration of vinyl sugars to form cyclopentenones.

Kitagawa M, Takegami S, Tokiwa Y (1998), Free-radical polymerization of a reducing vinyl sugar ester in dimethylformamide and water , Macromol Rapid Commun, 19, 155-158. 

Kitagawa M, Fan H, Raku T, Shibatani S, Maekawa Y, Hiraguri Y, Kurane R, Tokiwa Y (1999), Selective enzymatic preparation of vinyl sugar esters using DMSO as a denaturing co-solvent , Biotechnol Lett, 21, 355-359. 

Shibatani S, Kitagawa M, Tokiwa Y (1997), Enzymatic synthesis of vinyl sugar ester in dimethylformamide , Biotechnol Lett, 19, 511-514. 

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