Dendrimer sugar derivatives

Figure 7.13 Lactone sugar derivatives can be used to react with amine-containing dendrimers, which results in coupling via amide bonds. The sugar ball dendrimers then can be used to specifically bind to carbohydrate binding proteins.

The chemoselective character of this reaction permits the use of unprotected glycosyl thiols.92 With a similar strategy, an unprotected sugar derivative has been linked to 2-mercaptoacetyl-functionalized dendrimer forming a disulfide bond.93... 

Recently, a combination of fluorous substituents and a sugar-derived structure allowed the preparation of the scC02-soluble copolymer 53 as a novel phase-transfer catalyst (Figure 4.8). ° Dendrimers with fluorous substituents were also prepared for the same use. ° They are soluble in dense carbon dioxide and can solubilize otherwise C02-insoluble compounds such as Pd-nanoparticles (Scheme 92). The resulting dendrimer-encapsulated Pd catalyzes the hydrogenation of styrene and the Heck reaction of phenyl iodide. 

After cooling to room temperature, the sugar-dendrimer derivative may be precipitated with a large volume of methanol. The precipitate may be purified from reaction products by dialysis against water or buffer using a membrane with a molecular weight cutoff of 3500 Daltons. The final product may be stored frozen or lyophilized to a white powder. 

Scheme 7.8. Synthesis of sugar balls by treatment of PAMAM-type dendrimers with galacto- (or gluco-) pyranosyl lactone derivatives.

Fig. 22 Liquid crystal dendrimers with sugar based scaffold. Top, all of the sugar units are derived from glucose, whereas for the lower structure, the central sugar is glucose, and the others are derived from mannose.

Amphiphilic dendrimers derived from polyamidoamine and sugar lactones can also affect the enantioselectivity of NaBH4 reduction of prochiral ketones including dialkyl ketones giving unprecedented enantioselectivity (up to 96% ee for 2-heptanone). ... 

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