Sugar polysiloxanes

K. Beppu, Y. Kaneko, J-I. Kadokawa, H. Mori, T. Nishikawa, Polymer J., 2007, 39(10), 1065-1070. Synthesis of sugar-polysiloxane hybrids having rigid main-chain and formation of their nano aggregates ... 

Beppu, K. Kaneko, Y. Kadokawa, J.-L Mori, H. Nishiksawa, T., Synthesis of Sugar-Polysiloxane Hybrids Having Rigid Main-Chains and Formation of Their Nano Aggregates. Polym. J. 2007, 39,1065-1070. 

Common chiral stationary phases for gas chromatography have cyclodextrins bonded to a conventional polysiloxane stationary phase.7-8 Cyclodextrins are naturally occurring cyclic sugars. P-Cyclodextrin has a 0.78-nm-diameter opening into a chiral, hydrophobic cavity. The hydroxyls are capped with alkyl groups to decrease the polarity of the faces.9... 

There have been many reported chiral stationary phases for use in both packed and capillary gas chromatography. Most of these phases are of the carbonyl-bis-L-valine isopropyl ester, diamide, and peptide phase types. The most common phase is Chirasil-Val from Alltech Applied Science Laboratories (State College, PA). This phase is ideal for the separation of a variety of enantiomers including amino acids, sugars, amines, and peptides. The phase is composed of L-valine-tert-butylamide linked through a car-oxamide group to a polysiloxane backbone every seven dimethylsiloxane units apart. 

Abstract This article reviews the methods described to date for the preparation of polysiloxanes with weU-deflned structures containing sugar groups either as side-chain groups, end-groups or included in the main chain. 

Keywords Carbohydrate sugar glyco polysiloxane glycopolysiloxane hydrosilylation polymer glycopolymer... 

In this article, we reviewed the different ways described to date for the synthesis of well-defined glycosilicones or glycopolysiloxanes . They have been called also carbohydrate (-grafted, -functional, -modified) polysiloxanes , sugar (-grafted... etc) polysiloxanes , or sweet polysiloxanes . We focussed on the advantages and drawbacks of each method. 

In this review, we addressed the synthesis of well-defined monodimensional sugar-grafted polysiloxanes. For this reason, we excluded from this paper the synthesis of silicones (poly)-glycosides as surfactants, obtained by glycosylation of hydroxyl-terminated polysiloxanes and the preparation of polysaccharide-silicone adducts. Both are essentially described in patents, from which straighforward data concerning the sttucture of the products and the outcome of the reactions are difficult to extract. For silicone glycosides, some descriptions can be found, only in patents, for example in US 5,428,142 [2]. They are usually prepared by a Fischer... 

Fig. 2 Grafting of a sugar lactone on an amino-polysiloxane obtained from an epoxy-polysUoxane...

Attempts for Grafting Unprotected Sugars on Polysiloxanes by Hydrosilylation... 

An attempt to perform the same reaction with 6-O-aUylgalactopyranose without protection of the hydroxyl groups failed due to the large difference between the miscibility of sugars and polysiloxane. They could not find a suitable solvent chemically inert able to solubilise both reagents. While THF/methanol mixture dissolves both of the components, in this case, even traces of methanol in the reaction media react with the polymer hydrosilane functions to form ether bonds. 

Stadler et al. has synthesized several sugar-grafted polysiloxanes obtained by multistep procedures, including the preparation of the protected allyl-functionalized-sugars, the hydrosilylation with a statistical poly(dimethyl-co-hydrogenomethyl)-siloxane and finally the removal of the carbohydrate protective groups. 

Fig. 14 Grafting of unprotected sugars on azido-polysiloxanes by click chemistry ...

Fig. 15 Grafting of an unprotected sugar on an acetal-functionalized polysiloxane by acetalation...

An original approach for combining polysiloxanes and sugars has been reported by Thiem et al. [32] and Domschke et al. [33], with the preparation of main-chain carbohydrate-polysiloxane copolymers. In these structures, the sugar units are... 

The same gronp described the preparation of sugar-grafted polysiloxanes, by hydrosilylation of a trimethylsilyl-protected allylgluconamide, followed by deprotection with BFj-Et O in dry dichloromethane at -10°C [40]. This strategy is similar to what was described by Stadler et al. At this stage, the status of the polysiloxane after the deprotection reaction was not specified. 

In fact, a lot remains to be done for getting a clear knowledge of the relationships between structure and properties of sugar-grafted polysiloxanes. Both the set up of easier syntheses and a better knowledge of their properties would help their development. 

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