Spacer linkage

Katzhendler J, Cohen S, Rahanim E, Weisz M, Ringel I, Deutsch A. The effect of spacer linkage and solid-support on the synthesis of oligonucleotides. Tetrahedron 45 2777-2792, 1989. 

A limitation of this approach was the fact that the cyclization could not be accomplished on the resin. This would preclude further functionalization of the core. Therefore an alternate approach was to link the resin to the core via an aminoalcohol spacer as in 93. Furthermore, since linkage was conducted through the P-ketoester component rather than through the nitrogen atom, dihydropyridines 94 could now be formed on the solid support. When the 4-aryl substituent of 94 was nitro, on-resin reduction to the corresponding amine was possible. This allowed for further addition of diversity elements to the core scaffold before cleavage from the resin. 

Hydrosilation reactions have been one of the earlier techniques utilized in the preparation of siloxane containing block copolymers 22,23). A major application of this method has been in the synthesis of polysiloxane-poly(alkylene oxide) block copolymers 23), which find extensive applications as emulsifiers and stabilizers, especially in the urethane foam formulations 23-43). These types of reactions are conducted between silane (Si H) terminated siloxane oligomers and olefinically terminated poly-(alkylene oxide) oligomers. Consequently the resulting system contains (Si—C) linkages between different segments. Earlier developments in the field have been reviewed 22, 23,43> Recently hydrosilation reactions have been used effectively by Ringsdorf 255) and Finkelmann 256) for the synthesis of various novel thermoplastic liquid crystalline copolymers where siloxanes have been utilized as flexible spacers. Introduction of flexible siloxanes also improved the processibility of these materials. 

In this paper two new polymerized vesicle systems have been presented. The first lipid can be polymerized in vesicle through UV irradiation. Because the second lipid contains a flexible spacer group it can be prepolymerized in benzene and then converted to vesicles by ultrasonication in water. The polymerization improves the stabilities of the synthetic liposomes. Since there is a acetal linkage between the... 

Different types of protein or ligand linkages to hydroxylic matrices via spacers are shown in the following three examples ... 

S. Hana, T. Yoshida, and T. Uryu, Synthesis of a new polylysine-dendritic oligosaccharide with alkyl spacer having peptide linkage, Carbohydr. Polym., 69 (2007) 436 144. 

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