Soluble polymeric supports

Polyethylene glycol) (PEG) was used as a soluble polymeric support in the efficient preparation of the 2-benzazepine 58 via a phosphine-free palladium-catalysed Heck reaction from 57 <06T10456>. 

Oligosaccharide syntheses employing enzymatic reactions would in principle greatly benefit from being performed on a polymer support since the support might effectively facilitate isolation of the final product. Presumably, a water-soluble polymeric support will be preferable to any insoluble support since reaction rates could otherwise become too slow. Glycosidases as synthetic enzymes would be the best candidates to study this type of the enzymic approach to oligosaccharide synthesis. 

This book covers all of the most recent (at the time of writing) developments in the field of solid support oligosaccharide synthesis. Included are chapters discussing different synthetic strategies, glycosylation protocols, the use of solid supports versus soluble polymeric supports and on-resin analytical methods. Special topics such as the formation of [3-glycosidic linkages on solid support are also discussed. 

Many different soluble polymers have been used as supports for catalyst immobilization. Since solvation of otherwise insoluble catalysts can frequently be accom-pHshed by attachment to a soluble polymer, these supports have found significant use in the immobihzation of classical solution phase catalysts. Here, we will only survey polyethylene glycol (PEG) as a soluble polymeric support for catalysis. The use of other types of soluble polymers (e.g., polyethylene, non-cross-linked polystyrene) has been reviewed elsewhere [49]. 

Nishimura and Yamada [10-11] introduced a water-soluble polymeric support having a linker recognized by ceramide glycanase for a synthesis of ganghoside GM3 (17). Synthesis of the polymerizable lactose derivative (14) with a ceramide glycanase sensitive linker is shown in Scheme 10.3. The lactosyl ceramide (Lac-Ger) mimetic glycopolymer (15) is obtained from the monomeric precursor (14) by co-polymerization with acrylamide. 

An extension of solution-phase approaches which allows the possibility of combining the advantages of solution- and solid-phase syntheses is afforded by the use of soluble polymeric supports (see Fig. 5). Janda and co-workers [20,21] developed a technique... 

The selected example by Chen and Janda [175] reported the validation of a method for the synthesis of prostanoid libraries on a soluble polymeric support made by non-crosslinked chloromethylated polystyrene (NCPS). The synthesis of supported PGE2 methyl ester is shown in Figure 7.23. 

Bonora GM, Scremin CL, Colonna FP, Garbesi A, HELP (high efficiency liquid phase) new oligonucleotide synthesis on soluble polymeric support, Nucleic Acid Res., 18 3155-3159, 1990. 

These results point to the fact that the steric complications inherent of the heterogeneous solid-phase reactions occuring in cross-linked polymeric matrices are not solved completely by the use of the corresponding non-crosslinked soluble polymeric supports. The equivalence of all functional groups attached to the linear macromolecular chain, therefore, appears to be a prerequisite for the attainment of the reaction facility prevailing in low-molecular weight systems. 

Aminomethyl-3-nitrobenzoylpolyethyleneglycols are another class of photosensitive soluble polymeric supports designed for the liquid phase synthesis of protected peptide amides 192,193) (scheme 8). These supports have been very recently used for efficient synthesis of three biologically active 14-peptideamides corresponding to the wasp venom peptides, mastoparan, mastoparan X and Polistes mastoparan 198). 

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